Halide perovskite-based nanomaterials for the detection and photocatalytic removal of gaseous pollutants

Zhijian Xiao ^a, Jialin Li ^a, Xueyi Mai ^b, Jingling Yang *^a and Mingshan Zhu *^a
aGuangdong Key Laboratory of Environmental Pollution and Health, College of Environment and Climate, Jinan University, Guangzhou, 511443, P.R. China. E-mail: yangjl@jnu.edu.cn; zhumingshan@jnu.edu.cn
^bEnvironmental Technology, Wageningen University & Research, Wageningen, 6708 WG, The Netherlands

First published on 5th July 2024

---

---

Zhijian Xiao

Zhijian Xiao received his Bachelor's degree from Guangzhou University in 2022. Then, he joined Prof. Mingshan Zhu's group as a Master's candidate. His current research focuses on the application of halide perovskites and porous nanomaterials in the photocatalytic purification of nitric oxide.

Jingling Yang

Jingling Yang received her PhD from Sun Yat-sen University. Then she worked as a postdoctoral researcher at National Taiwan University (2016–2019). Currently, she is an Associate Professor at Jinan University. Her current research focuses on the field of catalytic purification of gaseous pollutants.

Mingshan Zhu

Mingshan Zhu received his PhD from Institute of Chemistry, Chinese Academy of Sciences (ICCAS), China. Then, he worked as a postdoctoral fellow at University of Toronto (2014–2015) and Osaka University (JSPS, 2015–2017). Currently, he is a Full Professor at Jinan University. His current research mainly focuses on the field of water pollution control chemistry.

---

1 Introduction

With the development of global industrialization, the contradiction between the development of human society and environmental protection has become increasingly prominent, causing people to pay more attention to serious environmental problems such as air pollution.^1–3 Pollutant gases emitted by automobiles and industry will intensify the greenhouse effect and trigger extreme weather phenomena. They will also produce fine particles in the atmosphere and lead to the formation of acid rain, adversely affecting air quality and human health. Volatile organic compounds (VOCs) serve as crucial precursors of ozone formation in the atmosphere and also contribute to haze and air pollution.^4,5 Therefore, the quest for efficient and environmentally friendly techniques to eliminate and detect gaseous pollutants has emerged as a global challenge embraced by researchers worldwide.^6,7

The traditional air purification technique usually consumes a lot of energy and may produce by-products or secondary pollutants, ultimately leading to energy waste, increased costs, and secondary pollution. Photocatalytic technology, as a green technology that could reduce energy consumption and environmental pollution, can efficiently convert gaseous pollutants into harmless substances.⁸ However, the performance is still constrained by factors such as the high fabrication cost of most photocatalytic materials and the narrow photoresponse range, which restricts their application in photocatalysis.^9,10 Halide perovskites (HPs) have achieved great success in photovoltaics and optoelectronics, mainly due to their excellent photophysical properties, such as enhanced visible light absorption, long carrier diffusion length,^11,12 high carrier mobility,^13,14 high photoluminescence quantum yield,^15,16 low binding energy,¹⁷ and tunable bandgap.¹⁸ Halide perovskites also have attractive features such as facile synthesis method and low fabrication cost,^19,20 and are a kind of promising photocatalysts. Many researchers have begun to continually study the application of HPs and found that HPs also have excellent performance in the photocatalytic removal of gaseous pollutants. Halide perovskites not only have excellent optical properties and can be applied in the field of photocatalysis but also show high sensitivity to specific gases and superior electrical properties, which have attracted widespread attention from scientists. The halide perovskite sensor exhibits high sensitivity, selectivity, fast response/recovery time, and acceptable stability at low concentrations at room temperature.^21–24 Due to its unique advantages and ideal performance in gas detection, researchers have paid great attention to the application of halide perovskites in gas sensor research. In organometallic halide perovskites, when the perovskite is exposed to target gas molecules, its resistance decreases within seconds and recovers immediately after it leaves the atmosphere.

According to the classification of gaseous pollutants, this article summarizes the application mechanism of halide perovskites in photocatalytic removal and detection of gaseous pollutants, and introduces their latest progress in these aspects. Finally, perspectives on the future developments in those fields are given (Fig. 1).

2 Basic properties of halide perovskites

Perovskites refer to a class of compounds that have the same crystal structure as CaTiO₃ (ABX₃). Halide perovskites are ionic crystals with the general formula ABX₃, where A is a monovalent cation (e.g., CS⁺, formamidinium (FA⁺)), B is a divalent metal cation (e.g., Pb²⁺, Cu²⁺, Sn²⁺), and X is a halogenated anion (e.g., Cl⁻, Br⁻, I⁻). The halide perovskite is an octahedral structure with the A-site cation at the apex and the B-site cation at the center of the octahedron, which cooperates with six X anions to form [BX₆]⁴⁻ (Fig. 2a). The structure of the perovskite is constrained by the tolerance factor, which is expressed by t = (R_A + R_B)/ (R_X + R_B), where R_A, R_B, and R_X are the ionic radii of the corresponding ions. Tolerance factors (t) should be between 0.8 and 1.1. Organic cations such as methylammonium or formamidinium can occupy the A site in the perovskite structure, which is known as an organic–inorganic hybrid halide perovskite. Due to their larger size, organic cations typically cause instability in the perovskite structure, disrupting the crystal lattice and promoting ion migration. Replacing them with inorganic cations, such as Cs⁺, significantly increases the stability, creating a pure inorganic halide perovskite. The B site is usually a Pb element, but the structure of three-dimensional lead-based perovskite is unstable, and Pb is highly toxic, tending to cause environmental pollution. Therefore, researchers have started to explore HPs with other compositional structures and compositions. Examples include A₄BX₆ (0D perovskite), AB₂X₅ (2D perovskite) and biphasic perovskite (A₂B⁺B₃⁺X₆). In the structure of biphasic perovskite, two toxic lead ions are replaced by a monovalent cation and a trivalent cation or a tetravalent cation and an empty site.²⁴

For the application of halide perovskites in photocatalytic technology and gas detection devices, the relatively special optoelectronic and structural properties of these materials are important issues to be considered. The three sites A, B and X of halide perovskite all have high solid solubility. Compared with traditional single-cation perovskites, mixed-cation halide perovskites and organic halide perovskites obtained by changing the A-site element have better performance and light-harvesting ability in terms of thermal, stress, structure, and photostability.²⁵ For the B site, the unique atomic electronic structure of Pb is critical to the performance of the perovskite. Taking CsPbI₃ as an example, the Pb 6p states form the bottom of the conduction band, which exhibits triple degeneracy due to the O_h symmetry, while the top of the valence band consists of the antibonding states of the Pb 6s and I 5p states. The energy levels of occupied ns² states and unoccupied np⁰ states can increase in the order Bi < Sb < Pb < Sn < Tl < In.²⁶ Such results will lead to smaller bandgaps and higher carrier mobility. Moreover, lead as an environmental toxic element can be substituted by elements with similar electronic structures and comparable ionic radii, where the bandgap can be changed close to the optimal range of the Shockley–Queisser limit.^25,27 Meanwhile, changing of halide ions at the X position or adjusting their chemical ratio can tune the bandgap of the halide perovskites. Therefore, the light absorption of halide perovskites can be tuned over a wide spectral range (from ultraviolet to near-infrared), making them more suitable for photocatalytic technologies and fluorescent gas detection devices.²⁸

3 Halide perovskites for photocatalytic removal of gaseous pollutants

3.1 Photocatalytic reaction mechanism of halide perovskites

The photocatalytic mechanism of halide perovskites is similar to that of conventional semiconductors. However, halide perovskites differ from traditional semiconductors due to their unique crystal structure and surface properties, which typically exhibit high specific surface areas and abundant surface defects that can promote surface reactions and enhance photocatalytic activity. Halide perovskites act as a trap for sunlight, absorbing photons with energy equivalent to or greater than the bandgap. This process transfers electrons from the valence band to the conduction band, leaving holes (h⁺) behind and forming photogenerated electron–hole pairs. Under the influence of internal electric field forces, photogenerated electrons and holes migrate to the surface of the semiconductor and react with adsorbed oxygen and oxides to form hydroxyl radicals (·OH) and superoxide radicals (·O₂⁻). These radicals have a strong oxidizing ability and can react with pollutants, providing a means to achieve removal and degradation. For the photogenerated carriers to better drive the photocatalytic reaction, the conduction band (CB) side of the HPs should be more negative than the reduction potential of the reacting substrate and the valence band (VB) side should be more positive than the oxidation potential of the reacting substrate. Also, considering the appropriate use of light, the bandgap should be optimal within a certain range, so the reasonable bandgap for photocatalytic applications of semiconductors should be 1.8–2.8 eV.²⁹ Materials with this bandgap range can absorb photon energy in the visible range and convert it into electron and hole pairs, thereby participating in photocatalytic reactions. This enables them to effectively perform photocatalytic reactions under sunlight or artificial light sources, unlike some traditional catalysts that can work only under ultraviolet light. Fig. 2b shows the energy level structures of several common halide perovskites, which are beneficial for the photocatalytic removal of NO and degradation of organic pollutants. Fig. 2c shows the mechanism of photocatalytic removal of NO and VOCs over halide perovskite catalysts. In the first step, the halide perovskite is excited by light. In the second step, photogenerated electron–hole pairs are generated, which react with adsorbed oxygen or oxides to produce ·OH and ·O₂⁻. In the third step, NO can be oxidized to NO₂ by photogenerated holes or hydroxyl radicals generated by light excitation of the halide perovskite catalyst, and NO₂ can continue to be oxidized to nitrate ions by hydroxyl groups or superoxide radicals. Volatile organic compounds can also be degraded by reacting with photogenerated electrons, photogenerated holes, and reactive oxygen species. For example, benzyl alcohol can react with superoxide radicals or photogenerated holes to form benzaldehyde. Toluene can react with photogenerated holes to form benzaldehyde as well. However, photogenerated carriers are prone to recombination when migrating to the semiconductor surfaces, which is not favorable for photocatalytic reactions.³⁰ Due to their defect-tolerant properties, halide perovskites are not prone to structural changes or lattice defect formation, which helps to extend the lifetime of the catalyst. This feature enables it to maintain a low defect concentration, thereby maintaining the richness and activity of catalytic active sites, and with higher carrier utilization efficiency.³¹ This property plays a key role in photocatalysis and helps to achieve better photocatalytic performance.

3.2 Photocatalytic removal of NO

Fossil fuel combustion provides 80% of the world's energy demand. As a non-renewable resource, the massive use of fossil fuels not only leads to energy shortage problems but also produces toxic gases such as NO during combustion. Emissions of NO cause photochemical smog, haze, and acid rain.³² Removal of NO by photocatalytic conversion to NO₃⁻ and other products is a more environmentally friendly method. Efficient photocatalysts for NO removal have been the focus of extensive research efforts aimed at mitigating air pollution and improving air quality. However, most photocatalysts have shortcomings such as limited photoresponse (UV region), low catalytic activity, poor stability, and high NO₂ selectivity. Owing to their reasonable bandgaps and high efficiency in photogenerated carrier migration, halide perovskites have attracted attention for NO elimination.

3.3 Photocatalytic removal of VOCs

Volatile organic compounds include aliphatic, aromatic, oxygen-containing, halogen-containing, nitrogen-containing hydrocarbons, and sulfonyl compounds. Their sources can be categorized into natural and anthropogenic sources. Natural releases consist of uncontrollable emission sources such as forest fires and green vegetation, while anthropogenic sources include fuel combustion, transportation, coal, natural gas, and other combustion sources. Most VOCs possess an unpleasant odor and are toxic, irritating, teratogenic, and carcinogenic, especially benzene, toluene, and formaldehyde, which can pose significant health risks to humans. The utilization of photocatalytic technology to degrade volatile organic pollutants is environmentally friendly. Photocatalytic processes typically involve converting volatile organic compounds into less harmful substances such as water vapor, carbon dioxide, and mineralization by-products. Halide perovskites can be designed to selectively target specific VOCs, minimizing the production of by-products and improving the overall efficiency of pollutant degradation, thereby not only reducing the generation of secondary pollutants but also contributing to more efficient air purification.

4 Applications of halide perovskites in gas sensing

4.1 Mechanism of gas sensing over halide perovskites

A chemical sensor is a device that senses a specified measured substance and converts it into chemical information according to certain laws. The above-mentioned chemical information may come from the chemical reaction of the substance being analyzed or from the physical properties of an analyzed system.⁵⁹ Chemical sensors typically consist of two main components: a receptor for detecting the target substance and a signal transducer. Semiconductor gas sensors are categorized according to their sensitivity mechanism and are generally divided into non-resistive and resistive types. Resistive sensors rely on changes in electric resistance to indicate gas sensitivity characteristics. Non-resistive gas sensors, such as electrochemical gas sensors, promote a chemical reaction on the surface of the gas-sensitive electrode, which results in a change in electrode charge. The change in charge generates electrical signals by which the composition and concentration of the gas can be determined. By utilizing these different sensing mechanisms, chemical sensors provide versatile solutions for detecting and quantifying various gases in a variety of applications.

Halide perovskite gas sensors exhibit better sensitivity, selectivity, stability and reliability that can be applied to detecting a wide range of gaseous pollutants.⁶⁰ The interaction between halide perovskites and their hybrid materials with detected gas molecules not only influences the color, photostability, and physicochemical properties of the materials but also significantly impacts their optical and photovoltaic properties. Optical property-related gas sensors can consist of a perovskite layer deposited on a material A layer (e.g., TiO₂) on an underlying fluorine-doped tin oxide (FTO) glass substrate (Fig. 9a). The top electrode is connected to the top surface of the perovskite layer through probe B (e.g., Au), while the bottom electrode is interconnected with the top electrode, allowing gas molecules to come into contact with most of the material's surface. Under light irradiation, the perovskite layer generates electron–hole pairs. Subsequently, the photogenerated electrons transferred from the CB of the perovskite material are transferred to the FTO through the A layer, while the VB holes of the perovskite material are gathered at the B probe, leading to a net current flowing from the FTO to Au through the output circuit without applying any external bias. The generated photocurrent is used to effect changes in the electrical properties of the perovskite-based detection device caused by interactions with gas molecules.

Halide perovskite capacitive gas sensors operate on the principle of changes in capacitance when the sensor device is exposed to a specific gas. The sensing mechanism involves changes in the electrical properties of the perovskite material due to interaction with the target gas. When a halide perovskite sensing layer comes into contact with a target gas, interactions occur between the gas molecules and the surface or bulk of the perovskite material. These interactions may involve adsorption, desorption, or chemical reactions. If gas adsorption causes an increase in carrier concentration or conductivity within the perovskite layer, it can affect the effective dielectric constant and thus the capacitance of the sensor. Changes in capacitance are correlated with the concentration or presence of the target gas, enabling gas detection and quantification (Fig. 9b). Halide perovskites are used as the sensitive layer of the sensor, and their surfaces are usually modified with specific molecules or functional groups for adsorbing target gas molecules. This adsorption can change the fluorescence properties of perovskites, especially by quenching fluorescence. They may cause changes in the surface charge state or cause changes in the local electric field. These changes can affect the fluorescence intensity or emission spectrum of the perovskite. The presence and concentration of target gas molecules are detected by measuring the fluorescence signal of halide perovskite fluorescent gas sensors. This usually involves the use of optical detection techniques to analyze changes in fluorescence intensity. There is usually a quantitative relationship between the change in the fluorescence signal and the concentration of the target gas, allowing the sensor to monitor changes in gas concentration in real time. The interaction between gas molecules and halide perovskites leads to detectable and quantifiable changes in luminescence, and even color changes can be observed with the naked eye (Fig. 9c).

4.2 Halide perovskite-based sensor devices for NO_x detection

Nitrogen oxides can contribute to the formation of acid rain, photochemical smog, and other pollutants that pose threats to both the ecosystem and human health, potentially causing harm to the eyes and lungs.^62–67 Consequently, implementing gas sensors for the monitoring of trace amounts of NO_x becomes crucial as a preventative measure against these environmental hazards. Traditional NO sensing metal oxides typically exhibit higher concentration NO detection limits,^68–70 and some require high operating temperatures (>60 °C).⁷¹ This may be a result of the weak interactions between the metallic elements and the nitrogen oxides.⁷² Thus, the key to advancing NO_x sensing materials, characterized by low operating temperatures and heightened sensitivity, involves exploring new elements with enhanced binding strength to NO_x. Halide perovskites have attracted considerable interest in academic research because of their superior optical properties, high sensitivity, and low detection limits.

Inspired by Te–N orbital coordination, Lu et al. obtained Cs₂TeI₆ from the reaction of CsI and TeI₄.⁷³ The mixed powder of CsI and TeI₄ was dissolved in DMF/DMSO (molar ratio is 1:1) to prepare a precursor, and the precursor was quickly injected into isobutanol to obtain fern-like Cs₂TeI₆ crystals. The octahedral structure of Cs₂TeI₆ crystals forms a new shape due to phase collapse (Fig. 10a). The diameter of the fern-like Cs₂TeI₆ crystal was observed by FESEM to be approximately 700 nm (Fig. 10b). At room temperature, the synthesized Cs₂TeI₆ achieved a detection level of 60 ppb for NO in halide perovskites, which represents the lowest reported value for NO detection in halide perovskites. Furthermore, its high selectivity for NO and material stability demonstrates its excellent sensing performance. After NO comes into contact with the surface of Cs₂TeI₆, Te–N orbital coordination between NO and Cs₂TeI₆ gradually occurs, leading to an increase in current. When the supply of NO gas is stopped, the curve returns to near its original state (Fig. 10c). At 400 ppb NO concentration, the sensor response time under N₂ purge was 138 seconds, and the recovery time was 152 seconds. Choi et al. successfully synthesized single crystal MHP NWs through an improved reverse LARP method (Fig. 10d).⁷⁴ The authors introduced a DEP process on MAPbCl₃ and MAPbBr₃ NWs, in which the DEP force and torque were applied to the NWs in the fluid medium (i.e., toluene), such that the MHP NWs were directionally deposited relative to the side, resulting in a consistent and controllable arrangement of the NWs (i.e., self-arrangement). The relative equilibrium of hydrodynamic and DEP forces can describe the NW motion (Fig. 10e). The MAPbBr₃ NW sensor exhibits a consistent and substantial response to reductive gases such as H₂S (about 120%, 100 ppm) and NH₃ (about 80%, 100 ppm) compared to oxidizing gases (i.e., NO₂). Notably, positive changes in resistance were observed for both reductive and oxidative gases, indicating that carrier transport in the NW network is hindered by adsorption whenever target gas molecules are present. Their response is highly dependent on the dominant carrier type of the sensing material (n-type or p-type) and the properties of the gas analyte that donates or accepts electrons. The development of sensors to detect trace amounts of toxic gases is necessary. Yang et al. deposited a lead-free all-inorganic cesium copper iodide (CsCu₂I₃) perovskite as a gas-sensitive layer on a digital interelectrode pattern substrate through a simple spin-coating precursor.⁷⁵ The sensing performance of the perovskite CsCu₂I₃ nanostructured network sensor was measured at an excitation voltage of 20 mV. The sensor has superior room temperature NO₂ sensing performance, including an extremely low detection limit, excellent stable repeatability and selectivity. The resistance of the perovskite CsCu₂I₃ nanonetwork sensor decreases under the action of oxidizing gas NO₂, showing typical p-type behavior. The ultrasensitive NO₂ sensing performance of the CsCu₂I₃ nanostructure network is primarily due to its unique nanoneedle cluster network structure and abundant iodine vacancies on the perovskite surface. The sensor has great potential for indoor trace contaminant detection due to its high sensitivity and environmental friendliness.

Shi et al. fabricated a resistive gas sensor based on SCN ion-doped CH₃NH₃PbI₃ (CH₃NH₃PbI_3−x(SCN)_x, SCN-OHP).⁷⁶ By continuously spin-coating Pb(SCN)₂ and CH₃NH₃I solutions on the surface of a gold interdigital electrode, the SCN-OHP material can be deposited on the sensing layer (Fig. 11a). Varying the thickness of the sensor layer has a significant effect on how it performs. The thinner the prepared sensing layer, the greater its specific surface area and the number of gas molecules it can adsorb. The sensor response (R) is the change in relative current at a bias voltage of 1 V: R = ΔI/I₀ = (I_ex − I₀)/I₀, where I₀ and I_ex represent the pre- and post-exposure recordings of the target gas sensor, respectively. Fig. 11b shows the results of detecting 500 ppb NO₂. In the range of 0.5 to 5 ppm, the sensor signal exhibits linear growth with increasing nitrogen dioxide concentration. Chizhov et al. synthesized a composite material based on nanocrystalline ZnO and colloidal cubic perovskite CsPbBr₃ NCs.⁷⁷ The CsPbBr₃ nanocrystals were wrapped with oleic acid and oleylamine. When the detected NO₂ concentration is stabilized at 3 ppm and the humidity is raised from 1% to 100%, the sensor signal decreases by 38.5%, but the detected absolute value is still high (Fig. 11c). The ZnO/CsPbBr₃ nanocomposite sensors showed response to NO₂ in the concentration range of 0.5–3.0 ppm under cyclic light in the temperature range of 25–100 °C. The pure nanocrystalline ZnO sensor could only show a response to NO₂ above 100 °C under the same conditions. The photogenerated electron transfer from CsPbBr₃ NCs to ZnO has a high electron transfer rate constant, which ensures the effective separation of the photogenerated carriers. The interaction between photogenerated carriers and adsorbed gas molecules is responsible for the increased gas sensitivity of nanocomposites compared to pure nanocrystalline ZnO.

4.3 Halide perovskite-based sensor devices for VOCs detection

Volatile organic compounds are a class of carbon-containing organic pollutants, most of which have low boiling points and are easily evaporated at room temperature. Volatile organic compounds pose a serious threat to human health, not only due to potential risks but also because of their adverse environmental effects, both in the short and long term. As people become increasingly concerned about the risks to public health associated with exposure to these hazardous VOCs, the demand for precise detection of these compounds is skyrocketing. Halide perovskites have the advantages of high sensitivity, low detection limits, fast response times, selectivity, versatility, and potential cost-effectiveness. These qualities make them promising candidates for the detection of volatile organic pollutants in a variety of environmental, industrial, and healthcare applications.

Chen et al. fabricated a CsPbBr₂I (CPBI) perovskite self-powered detection device, and Fig. 12a shows a cross-sectional SEM image of a typical CPBI device.⁷⁸ The photocurrent increases upon exposure to reducing gases (e.g., acetone and propane) and oxidizing gases (e.g., NO₂ and O₂). When reduced to an inert atmosphere, the photocurrent rapidly decreases. Under simulated sunlight, the CPBI device exhibited a linear response to both acetone and methanol over the test concentration ranging from 0 to 8 ppm, with a detection limit of 1 ppm for each (Fig. 12b). The authors proposed the chemical sensing mechanism of the CPBI detection device (Fig. 12c). Upon excitation by light, CPBI undergoes initial excitation, leading to rapid electron collection through the TiO₂ hole blocking layer on the FTO substrate, while the resulting holes are directly transferred to the top Au contact. Only photogenerated charges other than the recombination of photogenerated electrons and holes can be effectively collected to form the measured photocurrent. In the N₂ atmosphere, the reason for the weak PL intensity is that the nonradiative recombination between photogenerated charges is stronger, resulting in a relatively small photocurrent in the output circuit. Photoluminescence (PL) spectra intensity and photocurrent are significantly increased in the presence of O₂. This may be attributed to the passivation of trap states by O₂ molecules. Kim et al. prepared a fluorescent chemical sensor based on organic–inorganic hybrid CH₃NH₃PbBr₃ perovskite nanoparticles, which can be used to detect VOCs and aliphatic amines, including monoethylamine, diethylamine, and trimethylamine.⁶¹ The crystal structure of CH₃NH₃PbBr₃ is prone to structural changes, resulting in a burst of fluorescence signal when exposed to fatty amine gas. The detection of VOCs and fatty amine gas can be achieved by measuring their fluorescence intensity. After exposure to vapors of Et₃N and Et₂NH₂, the intensity of the PL spectrum light decreased rapidly (<1 s) and dropped sharply to 1.0% of the initial light intensity. The color change of the material before and after exposure to gas is also visible to the naked eye (Fig. 12d). The exposure intensity of the CH₃NH₃PbBr₃ film can be recovered reversibly at different ratios and with different rates of recovery after complete exposure. The crystal structure of organometallic halide perovskites can be disrupted by incorporating polar molecules (e.g., H₂O) into the perovskite lattice, which can form hydrogen bonds with the halide. This causes the hydrogen bonds in the original perovskite structure to be broken. The authors conducted DFT calculations and found that the hydrogen bond distances between the protons in EtNH₂, Et₂NH₂, and Et₃N and the nitrogen in CH₃NH³⁺ are 1.07, 2.25, and 3.58 Å, respectively. The findings indicate that increasing the distance between Et₃N and CH₃NH³⁺ weakens their interaction intensity, thereby enabling reversible fluorescence detection. However, the short distance between Et₃N and CH₃NH³⁺ leads to irreversible fluorescence detection behavior.

Takshi et al. studied the susceptibility and selectivity of methylammonium lead iodide (MAPbI₃) to methanol, ethanol, propanol, and isopropanol.⁷⁹ They first formed microchannels on indium tin oxide (ITO)-coated plastic substrates and then filled them with a solution of perovskite precursors by using capillary motion forces (Fig. 13a). The material has a more pronounced response to exposure to methanol vapors, with a percentage change in current exceeding 20% from +2.0 V to −2.0 V. Chen et al. deposited CsPbBr (CPB) on a fluorine-doped tin oxide layer to prepare the porous interconnection layer of the detector.⁸⁰ Electron microscopy analysis shows that there is a well-adhered and uniform CPB layer on the FTO surface, with an average thickness of 350 ± 5 nm (Fig. 13b). Fig. 13c shows the CPB sensor layout, morphology, structure, and optical properties. Under visible light irradiation, the material exhibits rapid sensing capability for acetone and ethanol at concentrations as low as 1 ppm in simulated atmospheres, with detection sensitivities of 0.03 and 0.025, respectively (Fig. 13d and e). The absolute value of the current is about 1.98 and 3.95 nA. The authors concluded that ethanol and acetone can serve as vacancy fillers to reversibly fill the inherent Br vacancies in CPB. The Br vacancies serve as traps for photogenerated charges, and when the device is subjected to the detection gas, the Br vacancy density decreases, allowing more photogenerated charges to be transported and thus an increase in photocurrent can be observed.

4.4 Halide perovskite-based sensor devices for other gaseous pollutant detection

Halide perovskites have an abundance of surface-active sites that can chemically adsorb and react with various gas molecules, resulting in changes in the optoelectronic properties of the material, such as conductivity, light absorption, etc. These changes in performance can be monitored by photoelectric property testing or electrical testing, allowing gas detection and identification. The halide perovskite sensor is therefore capable of detecting NH₃ and H₂S at various concentration levels with a wide detection range, fast response and recovery time.

Ghosh et al. reported a material (CH₃NH₃PbI₃/MAPI) as a fast-responsive, selective, and sensitive active material for visual and electrical detection of ammonia (NH₃) gas.⁸¹ The sensor is grown on commercially available cellulose paper and can selectively detect NH₃ gas at sub-ppm levels based on a visually visible color change (10 ppm) solution and highly sensitive electrical sensing. The sensor can also be used for visual and electrical sensing at room temperature. In the presence of a certain concentration of NH₃, the paper sensor made of MAPbI₃ and FAPbI₃ changed from black to yellow, while MAPbBr₃ changed from orange to white (Fig. 14a). Fig. 14b shows the current response of devices based on MAPB and FAPI at ambient temperatures with different NH₃ gas concentrations (ppm). The sensitivity (visual and electrical) diagrams of the three halide perovskites show that MAPI can perform visual detection and 10 ppb electrical detection at 10 ppm, MAPB can perform visual detection and 50 ppm electrical detection at 300 ppb, and for FAPI, the corresponding values are 80 ppm and 500 ppb, respectively (Fig. 14c). Saxena et al. synthesized ethylenediamine lead iodide chloride perovskite material.⁸² The color of the perovskite film was observed to change from yellow to orange when the prepared material was exposed to ammonia vapor. When exposed to a lower concentration of ammonia (50–200 ppm), the perovskite film changes color from yellow to orange and returns to yellow within approximately 60 seconds. It is also possible to detect ammonia vapor at various ppm concentrations from 50 ppm to 200 ppm for a certain period of time by resistance measurement (Fig. 14d). At the lower concentration of 50 ppm, the response time is longer (39 seconds) with a resistance change of 1.37 × 10¹⁰ Ω, while at higher concentrations, the sensor responds faster, with a minimum response time of 16.5 seconds at 200 ppm, and the resistance change is 1.68 × 10¹⁰ Ω. Ammonia vapor infiltration into the perovskite film induces the release of free electrons within its structure, thereby increasing conductivity. Therefore, the resistance change increases with increasing concentration. After reaching a certain concentration, further exposure does not result in an additional increase in conductivity because there are no available sites or voids on the surface of the material, so the resistance change becomes saturated at higher concentrations. Ayesh et al. fabricated a gas sensor for detecting H₂S gas based on FAPbBr₃ material.⁸³ The material exhibits excellent optical luminescence, good charge transport, and high sensitivity to gas molecules. It exhibits high sensitivity to H₂S gas in the form of conductivity changes, and the adsorption of H₂S gas on the nanoparticles results in changes in their surface charge, thereby changing their conductivity. The sensor's response to H₂S gas shows high sensitivity to gas concentrations in the range of 0.5–100 ppm (Fig. 14e).

Conclusion

In recent years, many interesting studies on HP-based photocatalysts have been reported and highlighted. However, the application of HPs in photocatalytic removal of gaseous pollutants remains in its nascent stages. Their overall performance and stability are currently unsatisfactory, limiting their efficiency in addressing energy and environmental issues, and facing several challenges. Halide perovskite gas sensors have attracted widespread attention due to their high sensitivity, high selectivity, and low cost. Despite the excellent performance of these sensors, several aspects of their practical applications require further exploration. This review clarified the mechanism of photocatalytic reaction and gas detection of halide perovskites. The materials were briefly classified, and the research on the photocatalytic removal of NO_x and VOCs and the detection of these pollutant gases were described.

Looking ahead, the research on halide perovskites presents both limitless opportunities and challenges. This field remains in the exploratory stage. Beyond the research content introduced in this review, halide perovskites also exhibit emerging development trends and challenges in other aspects:

(i) Halide perovskites are not only effective in the photocatalytic degradation of gaseous pollutants but also show promise in degrading organic dyes, organic wastes in wastewater, drug residues, and other pollutants. They can be utilized in industrial wastewater treatment and environmental restoration.

(ii) Halide perovskites can be applied to photocatalytic water splitting to produce hydrogen, thereby contributing to sustainable hydrogen energy production, reducing dependence on fossil fuels, and lowering greenhouse gas emissions. Additionally, their photocatalytic activity can inhibit bacterial growth, providing an antibacterial effect that enhances water and air quality.

(iii) The application of halide perovskite sensors extends from industrial settings to environmental monitoring. These sensors, characterized by their small size, light weight, and low power consumption, can be developed into portable or embedded gas monitoring devices for outdoor activities, indoor air quality testing, and industrial safety testing. They enable continuous gas monitoring and can be integrated into intelligent monitoring systems for real-time monitoring and data collection of urban air quality, thus providing a scientific basis for urban planning, traffic management, and environmental protection.

(iv) Organic halide perovskites have poor stability under humid conditions and high temperatures, which are susceptible to dissociation or loss of crystallinity in moisture, resulting in a decline in material performance. Therefore, limiting their use in environments such as solar cells where they are exposed to sunlight for long periods. Furthermore, the challenges in large-area preparation and scaling also limited their practical application. When preparing large-area films, it becomes more difficult to control the structure and quality of the crystals, often leading to crystal defects. This affects the long-term stability and reliability of the device. Achieving efficient halide perovskites usually requires strict process controls and conditions, which increases costs and introduces uncertainty into material production.

Regarding the practical application of halide perovskites, we believe that more and more scholars will devote themselves to solving the current problems, thus promoting the halide perovskites from laboratory research to industrialization.

Data availability

No primary research results, software or code have been included and no new data were generated or analysed as part of this review.

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

The authors acknowledge the support of the National Natural Science Foundation of China (22322604), the Guangdong Basic and Applied Basic Research Foundation (2022A1515010655), and the Pearl River Talent Recruitment Program of Guangdong Province (2021QN020272).

References

1. X. Qian, Y. Ma, X. Xia, J. Xia, J. Ye, G. He and H. Chen, Recent progress on Bi₄O₅Br₂-based photocatalysts for environmental remediation and energy conversion, Catal. Sci. Technol., 2023, 14, 1085–1104 RSC .
2. J. Wang, J. Xuan, X. Wei, Y. Zhang, J. Fan, L. Ni, Y. Yang, J. Liu, Y. Tian and X. Wang, Enhancing solar-to-hydrogen efficiency with an S-scheme GaTe/PtS₂ van der Waals heterojunction with high light absorption, Catal. Sci. Technol., 2023, 13, 4753–4764 RSC .
3. A. Ghosh, D. Nag, R. Chatterjee, A. Singha, P. S. Dash, B. Choudhury and A. Bhaumik, CO₂ to dimethyl ether (DME): structural and functional insights of hybrid catalysts, Catal. Sci. Technol., 2024, 14, 1387–1427 RSC .
4. G. Zhu, J. Zhou, D. Li and Z. Ao, Density functional theory study on the enhanced adsorption mechanism of VOCs by Cu₄ cluster decorated UiO-66, Surf. Interfaces, 2024, 46, 104199 CrossRef CAS .
5. N. Joshi, P. Gawas, A. Bora, L. Sivachandiran, Y. Sivalingam and V. Nutalapati, Effect of thermal treatment on zeolite for real-time gas sensing of oxygenated volatile organic compounds, Surf. Interfaces, 2023, 42, 103364 CrossRef CAS .
6. R. Li, Y. Rao and Y. Huang, Advances in catalytic elimination of atmospheric pollutants by two-dimensional transition metal oxides, Chin. Chem. Lett., 2023, 34, 108000 CrossRef CAS .
7. J. Wang, X. Tang, J. Li, S. Dong, X. Zhang and B. Liu, Fabrication of high-performance CeO₂–MnO_x/TiO₂/Ti monolithic catalysts for low-temperature and stable CO oxidation, Catal. Sci. Technol., 2023, 13, 3386–3394 RSC .
8. X. Li, P. Wang, S. Han, Y. Huang, W. Ho, S. S. H. Ho, S.-C. Lee and M. Wang, Development and application of photocatalytic coating for roadside NO_x mitigation in Hong Kong, Chin. Chem. Lett., 2024, 35, 108709 CrossRef CAS .
9. D. Song, M. Li, F. Yang, M. Yu, Z. Li, J. Chen, X. Zhang and W. Zhou, Plasmon Bi in-situ anchored on BiOCl nanosheets assembled microspheres towards optimized photothermal-photocatalytic performance, Chin. Chem. Lett., 2024, 35, 108591 CrossRef CAS .
10. H. Liu, S. Hussain, S. H. A. Jaffery, J. Lee, S. Aftab, J. Jung, H.-S. Kim, J. Kang and D. Vikraman, Construction of perovskite solar cells and X-ray detectors using the indium selenide-carbon nanotube hybrids tuned hole transporting layer, Surf. Interfaces, 2023, 41, 103234 CrossRef CAS .
11. G. Xing, N. Mathews, S. Sun, S. S. Lim, Y. M. Lam, M. Grätzel, S. Mhaisalkar and T. C. Sum, Long-range balanced electron-and hole-transport lengths in organic-inorganic CH₃NH₃PbI₃, Science, 2013, 342, 344–347 CrossRef CAS PubMed .
12. Q. Dong, Y. Fang, Y. Shao, P. Mulligan, J. Qiu, L. Cao and J. Huang, Electron-hole diffusion lengths > 175 μm in solution-grown CH₃NH₃PbI₃ single crystals, Science, 2015, 347, 967–970 CrossRef CAS .
13. L. Wang, H. Wang, M. Wagner, Y. Yan, D. S. Jakob and X. G. Xu, Nanoscale simultaneous chemical and mechanical imaging via peak force infrared microscopy, Sci. Adv., 2017, 3, e1700255 CrossRef PubMed .
14. Y. Yang, Y. Yan, M. Yang, S. Choi, K. Zhu, J. M. Luther and M. C. Beard, Low surface recombination velocity in solution-grown CH₃NH₃PbBr₃ perovskite single crystal, Nat. Commun., 2015, 6, 7961 CrossRef CAS PubMed .
15. S. Li, D. Lei, W. Ren, X. Guo, S. Wu, Y. Zhu, A. L. Rogach, M. Chhowalla and A. K.-Y. Jen, Water-resistant perovskite nanodots enable robust two-photon lasing in aqueous environment, Nat. Commun., 2020, 11, 1192 CrossRef CAS .
16. F. Liu, Y. Zhang, C. Ding, S. Kobayashi, T. Izuishi, N. Nakazawa, T. Toyoda, T. Ohta, S. Hayase and T. Minemoto, Highly luminescent phase-stable CsPbI₃ perovskite quantum dots achieving near 100% absolute photoluminescence quantum yield, ACS Nano, 2017, 11, 10373–10383 CrossRef CAS .
17. Y.-H. Kim, H. Cho and T.-W. Lee, Metal halide perovskite light emitters, Proc. Natl. Acad. Sci. U. S. A., 2016, 113, 11694–11702 CrossRef CAS .
18. F. Hu, H. Zhang, C. Sun, C. Yin, B. Lv, C. Zhang, W. W. Yu, X. Wang, Y. Zhang and M. Xiao, Superior optical properties of perovskite nanocrystals as single photon emitters, ACS Nano, 2015, 9, 12410–12416 CrossRef CAS .
19. A. A. Qureshi, S. Javed, A. Fakharuddin, M. A. Akram and L. Schmidt-Mende, Low-temperature processed natural hematite as an electron extraction layer for efficient and stable perovskite solar cells, Surf. Interfaces, 2023, 40, 103003 CrossRef CAS .
20. N. T. Shelke, M. Yewale, R. Kadam, U. Nakate, A. Jadhavar and D. Shin, Facile hydrothermal synthesis and fabrication of nickel cobalt oxide as an advanced electrode for electrochemical capacitors, Surf. Interfaces, 2023, 43, 103555 CrossRef CAS .
21. E. Gagaoudakis, A. Panagiotopoulos, T. Maksudov, M. Moschogiannaki, D. Katerinopoulou, G. Kakavelakis, G. Kiriakidis, V. Binas, E. Kymakis and K. Petridis, Self-powered, flexible and room temperature operated solution processed hybrid metal halide p-type sensing element for efficient hydrogen detection, JPhys Mater., 2020, 3, 014010 CrossRef CAS .
22. M.-Y. Zhu, L.-X. Zhang, J. Yin, J.-J. Chen, L.-J. Bie and B. D. Fahlman, Physisorption induced p-xylene gas-sensing performance of (C₄H₉NH₃)₂PbI₄ layered perovskite, Sens. Actuators, B, 2019, 282, 659–664 CrossRef CAS .
23. W. Jiao, J. He and L. Zhang, Synthesis and high ammonia gas sensitivity of (CH₃NH₃) PbBr_3-xI_x perovskite thin film at room temperature, Sens. Actuators, B, 2020, 309, 127786 CrossRef CAS .
24. L. Chu, W. Ahmad, W. Liu, J. Yang, R. Zhang, Y. Sun, J. Yang and X. A. Li, Lead-free halide double perovskite materials: a new superstar toward green and stable optoelectronic applications, Nanomicro Lett., 2019, 11, 1–18 CrossRef .
25. M. Saliba, T. Matsui, J.-Y. Seo, K. Domanski, J.-P. Correa-Baena, M. K. Nazeeruddin, S. M. Zakeeruddin, W. Tress, A. Abate and A. Hagfeldt, Cesium-containing triple cation perovskite solar cells: improved stability, reproducibility and high efficiency, Energy Environ. Sci., 2016, 9, 1989–1997 RSC .
26. Z. Xiao, K.-Z. Du, W. Meng, J. Wang, D. B. Mitzi and Y. Yan, Intrinsic Instability of Cs₂In(I)M(III)X₆ (M = Bi, Sb; X = Halogen) Double Perovskites: A Combined Density Functional Theory and Experimental Study, J. Am. Chem. Soc., 2017, 139, 6054–6057 CrossRef CAS PubMed .
27. C. Pi, W. Chen, W. Zhou, S. Yan, Z. Liu, C. Wang, Q. Guo, J. Qiu, X. Yu and B. Liu, Highly stable humidity sensor based on lead-free Cs₃Bi₂Br₉ perovskite for breath monitoring, J. Mater. Chem. C, 2021, 9, 11299–11305 RSC .
28. W.-J. Yin, Y. Yan and S.-H. Wei, Anomalous Alloy Properties in Mixed Halide Perovskites, J. Phys. Chem. Lett., 2014, 5, 3625–3631 CrossRef CAS .
29. M. G. Walter, E. L. Warren, J. R. McKone, S. W. Boettcher, Q. Mi, E. A. Santori and N. S. Lewis, Solar water splitting cells, Chem. Rev., 2010, 110, 6446–6473 CrossRef CAS PubMed .
30. M. A. Henderson, A surface science perspective on TiO₂ photocatalysis, Surf. Sci. Rep., 2011, 66, 185–297 CrossRef CAS .
31. H. Huang, M. I. Bodnarchuk, S. V. Kershaw, M. V. Kovalenko and A. L. Rogach, Lead halide perovskite nanocrystals in the research spotlight: stability and defect tolerance, ACS Energy Lett., 2017, 2, 2071–2083 CrossRef CAS .
32. G. Gao, Q. Xi, H. Zhou, Y. Zhao, C. Wu, L. Wang, P. Guo and J. Xu, Novel inorganic perovskite quantum dots for photocatalysis, Nanoscale, 2017, 9, 12032–12038 RSC .
33. J. Yang, X. Wang, H. Wang, F. Dong and M. Zhu, CsPbBr₃ perovskite nanocrystal: A robust photocatalyst for realizing NO abatement, ACS ES&T Eng., 2021, 1, 1021–1027 Search PubMed .
34. D. Wu, Y. Tao, Y. Huang, B. Huo, X. Zhao, J. Yang, X. Jiang, Q. Huang, F. Dong and X. Tang, High visible-light photocatalytic performance of stable lead-free Cs₂AgBiBr₆ double perovskite nanocrystals, J. Catal., 2021, 397, 27–35 CrossRef CAS .
35. J. Kou, C. Lu, J. Wang, Y. Chen, Z. Xu and R. S. Varma, Selectivity enhancement in heterogeneous photocatalytic transformations, Chem. Rev., 2017, 117, 1445–1514 CrossRef CAS .
36. J. Yang, B. Liu, L. Zeng, B. Du, Y. Zhou, H. Tao, Y. Yun and M. Zhu, Confining Bismuth-Halide Perovskite in Mesochannels of Silica Nanomembranes for Exceptional Photocatalytic Abatement of Air Pollutants, Angew. Chem., Int. Ed., 2024, e202319741 CAS .
37. B. Huo, J. Yang, Y. Bian, D. Wu, J. Feng, J. Zhou, Q. Huang, F. Dong and X. Tang, Amino-mediated anchoring of FAPbBr₃ perovskite quantum dots on silica spheres for efficient visible light photocatalytic NO removal, Chem. Eng. J., 2021, 406, 126740 CrossRef CAS .
38. Z. Guan, Y. Wu, P. Wang, Q. Zhang, Z. Wang, Z. Zheng, Y. Liu, Y. Dai, M.-H. Whangbo and B. Huang, Perovskite photocatalyst CsPbBr_3-xI_x with a bandgap funnel structure for H₂ evolution under visible light, Appl. Catal., B, 2019, 245, 522–527 CrossRef CAS .
39. Q. Xu, L. Zhang, B. Cheng, J. Fan and J. Yu, S-scheme heterojunction photocatalyst, Chem, 2020, 6, 1543–1559 CAS .
40. G. Zhang, C. Yuan, X. Li, L. Yang, W. Yang, R. Fang, Y. Sun, J. Sheng and F. Dong, The mechanisms of interfacial charge transfer and photocatalysis reaction over Cs₃Bi₂Cl₉ QD/(BiO)₂CO₃ heterojunction, Chem. Eng. J., 2022, 430, 132974 CrossRef CAS .
41. T. Tan, X. Wang, X. Zhou, H. Ma, R. Fang, Q. Geng and F. Dong, Highly active Cs₂SnCl₆/C₃N₄ heterojunction photocatalysts operating via interfacial charge transfer mechanism, J. Hazard. Mater., 2022, 439, 129694 CrossRef CAS .
42. F. Zhong, C. Yuan, Y. He, Y. Sun, J. Sheng and F. Dong, Dual-quantum-dots heterostructure with confined active interface for promoted photocatalytic NO abatement, J. Hazard. Mater., 2022, 438, 129463 CrossRef CAS .
43. B. Xie, D. Chen, N. Li, Q. Xu, H. Li, J. He and J. Lu, Fabrication of an FAPbBr₃/g-C₃N₄ heterojunction to enhance NO removal efficiency under visible-light irradiation, Chem. Eng. J., 2022, 430, 132968 CrossRef CAS .
44. Y. Zhang, W. Yu, S. Cao, Z. Sun, X. Nie, Y. Liu and Z. Zhao, Photocatalytic chemoselective transfer hydrogenation of quinolines to tetrahydroquinolines on hierarchical NiO/In₂O₃–CdS microspheres, ACS Catal., 2021, 11, 13408–13415 CrossRef CAS .
45. W. Weng, S. Wang, W. Xiao and X. W. Lou, Direct conversion of rice husks to nanostructured SiC/C for CO₂ photoreduction, Adv. Mater., 2020, 32, 2001560 CrossRef CAS PubMed .
46. D. Cardenas-Morcoso, A. S. F. Gualdrón-Reyes, A. B. Ferreira Vitoreti, M. García-Tecedor, S. J. Yoon, M. Solis de la Fuente, I. N. Mora-Seró and S. Gimenez, Photocatalytic and photoelectrochemical degradation of organic compounds with all-inorganic metal halide perovskite quantum dots, J. Phys. Chem. Lett., 2019, 10, 630–636 CrossRef CAS PubMed .
47. D. Wu, W. Sang, B. Huo, J. Wang, X. Wang, C. Chen, Q. Huang and X. Tang, Highly crystalline lead-free Cs₃Sb₂Br₉ perovskite microcrystals enable efficient and selective photocatalytic oxidation of benzyl alcohol, J. Catal., 2022, 408, 36–42 CrossRef CAS .
48. B. Bajorowicz, A. Mikolajczyk, H. P. Pinto, M. Miodynska, W. Lisowski, T. Klimczuk, I. Kaplan-Ashiri, M. Kazes, D. Oron and A. Zaleska-Medynska, Integrated experimental and theoretical approach for efficient design and synthesis of gold-based double halide perovskites, J. Phys. Chem. C, 2020, 124, 26769–26779 CrossRef CAS .
49. Z.-J. Bai, X.-P. Tan, L. Chen, B. Hu, Y.-X. Tan, Y. Mao, S. Shen, J.-K. Guo, C.-T. Au and Z.-W. Liang, Efficient photocatalytic toluene selective oxidation over Cs₃Bi_1.8Sb_0.2Br₉ Nanosheets: Enhanced charge carriers generation and C–H bond dissociation, Chem. Eng. Sci., 2022, 247, 116983 CrossRef CAS .
50. Y. Dai, C. Poidevin, C. Ochoa-Hernández, A. A. Auer and H. Tüysüz, A supported bismuth halide perovskite photocatalyst for selective aliphatic and aromatic C–H bond activation, Angew. Chem., 2020, 132, 5837–5845 CrossRef .
51. P. Qiu, Q. Wang, Y. Zhao, Y. Dai, Y. Dong, C. Chen, Q. Chen and Y. Li, Fabricating surface-functionalized CsPbBr₃/Cs₄PbBr₆ nanosheets for visible-light photocatalytic oxidation of styrene, Front. Chem., 2020, 8, 130 CrossRef CAS PubMed .
52. H. Huang, H. Yuan, K. P. Janssen, G. Solis-Fernandez, Y. Wang, C. Y. Tan, D. Jonckheere, E. Debroye, J. Long and J. Hendrix, Efficient and selective photocatalytic oxidation of benzylic alcohols with hybrid organic–inorganic perovskite materials, ACS Energy Lett., 2018, 3, 755–759 CrossRef CAS .
53. Q. Li, T. Song, Y. Zhang, Q. Wang and Y. Yang, Boosting Photocatalytic Activity and Stability of Lead-Free Cs₃Bi₂Br₉ Perovskite Nanocrystals via In Situ Growth on Monolayer 2D Ti₃C₂Tx MXene for C–H Bond Oxidation, ACS Appl. Mater. Interfaces, 2021, 13, 27323–27333 CrossRef CAS .
54. M. Zhang, W. Wang, F. Gao and D. Luo, g-C₃N₄-Stabilised Organic–Inorganic Halide Perovskites for Efficient Photocatalytic Selective Oxidation of Benzyl Alcohol, Catalysts, 2021, 11, 505 CrossRef CAS .
55. Z.-J. Bai, Y. Mao, B.-H. Wang, L. Chen, S. Tian, B. Hu, Y.-J. Li, C.-T. Au and S.-F. Yin, Tuning photocatalytic performance of Cs₃Bi₂Br₉ perovskite by g-C₃N₄ for C (sp³)—H bond activation, Nano Res., 2023, 16, 6104–6112 CrossRef CAS .
56. A. Ummadisingu, L. Steier, J.-Y. Seo, T. Matsui, A. Abate, W. Tress and M. Grätzel, The effect of illumination on the formation of metal halide perovskite films, Nature, 2017, 545, 208–212 CrossRef CAS .
57. Y. Lou, M. Fang, J. Chen and Y. Zhao, Formation of highly luminescent cesium bismuth halide perovskite quantum dots tuned by anion exchange, Chem. Commun., 2018, 54, 3779–3782 RSC .
58. Y. Yang, Z. Chen, H. Huang, Y. Liu, J. Zou, S. Shen, J. Yan, J. Zhang, Z. Zhuang and Z. Luo, Synergistic surface activation during photocatalysis on perovskite derivative sites in heterojunction, Appl. Catal., B, 2023, 323, 122146 CrossRef CAS .
59. S. Zampolli, I. Elmi, F. Ahmed, M. Passini, G. Cardinali, S. Nicoletti and L. Dori, An electronic nose based on solid state sensor arrays for low-cost indoor air quality monitoring applications, Sens. Actuators, B, 2004, 101, 39–46 CrossRef CAS .
60. X. L. Yu, Y. Wang, Y. M. Hu, C. B. Cao and H. L. W. Chan, Gas-Sensing Properties of Perovskite BiFeO₃ Nanoparticles, J. Am. Ceram. Soc., 2009, 92, 3105–3107 CrossRef CAS .
61. S.-H. Kim, A. Kirakosyan, J. Choi and J. H. Kim, Detection of volatile organic compounds (VOCs), aliphatic amines, using highly fluorescent organic-inorganic hybrid perovskite nanoparticles, Dyes Pigm., 2017, 147, 1–5 CrossRef CAS .
62. C.-Y. Lin, J.-G. Chen, C.-W. Hu, J. J. Tunney and K.-C. Ho, Using a PEDOT: PSS modified electrode for detecting nitric oxide gas, Sens. Actuators, B, 2009, 140, 402–406 CrossRef CAS .
63. H. Jin, Y. Huang and J. Jian, Plate-like Cr₂O₃ for highly selective sensing of nitric oxide, Sens. Actuators, B, 2015, 206, 107–110 CrossRef CAS .
64. J. Qiu, X. Hu, X. Min, W. Quan, R. Tian, P. Ji, H. Zheng, W. Qin, H. Wang and T. Pan, Observation of switchable dual-conductive channels and related nitric oxide gas-sensing properties in the N-rGO/ZnO heterogeneous structure, ACS Appl. Mater. Interfaces, 2020, 12, 19755–19767 CrossRef CAS PubMed .
65. B. Peng, Y. Zhou, G. Liu, Y. He, C. Gao and Y. Guo, An ultra-sensitive detection system for sulfur dioxide and nitric oxide based on improved differential optical absorption spectroscopy method, Spectrochim. Acta, Part A, 2020, 233, 118169 CrossRef CAS PubMed .
66. W. Tsujita, A. Yoshino, H. Ishida and T. Moriizumi, Gas sensor network for air-pollution monitoring, Sens. Actuators, B, 2005, 110, 304–311 CrossRef CAS .
67. J.-Y. Jeon, B.-C. Kang, Y. T. Byun and T.-J. Ha, High-performance gas sensors based on single-wall carbon nanotube random networks for the detection of nitric oxide down to the ppb-level, Nanoscale, 2019, 11, 1587–1594 RSC .
68. D. Degler, Trends and advances in the characterization of gas sensing materials based on semiconducting oxides, Sensors, 2018, 18, 3544 CrossRef PubMed .
69. J. Casanova-Cháfer, E. Navarrete, X. Noirfalise, P. Umek, C. Bittencourt and E. Llobet, Gas sensing with iridium oxide nanoparticle decorated carbon nanotubes, Sensors, 2018, 19, 113 CrossRef .
70. Q. Wu, W. Liu, X. Bu, H. Wu, C. Wang, X. Li and X. Wang, Graphene oxide/graphene hybrid film with ultrahigh ammonia sensing performance, Nanotechnology, 2020, 32, 115501 Search PubMed .
71. N. D. Chinh, N. D. Quang, H. Lee, T. Thi Hien, N. M. Hieu, D. Kim, C. Kim and D. Kim, NO gas sensing kinetics at room temperature under UV light irradiation of In₂O₃ nanostructures, Sci. Rep., 2016, 6, 35066 CrossRef CAS .
72. S. Hou, R. Pang, S. Chang, L. Ye, J. Xu, X. Wang, Y. Zhang, Y. Shang and A. Cao, Synergistic CNFs/CoS₂/MoS₂ flexible films with unprecedented selectivity for NO gas at room temperature, ACS Appl. Mater. Interfaces, 2020, 12, 29778–29786 CAS .
73. Z.-K. Chen, W. Ye, J. Wang, C. Yu, J.-H. He and J.-M. Lu, Sensitive NO detection by lead-free halide Cs₂TeI₆ perovskite with Te-N bonding, Sens. Actuators, B, 2022, 357, 131397 CrossRef CAS .
74. A. Kirakosyan, M. R. Sihn, M.-G. Jeon, R. M. Kabir and J. Choi, Self-aligned CH₃NH₃PbBr₃ perovskite nanowires via dielectrophoresis for gas sensing applications, Appl. Mater. Today, 2022, 26, 101307 CrossRef .
75. X. Sun, J. Yang, Z. Wu, G. Meng, X. Guo, D. Kuang, L. Xiong, W. Qu, X. Fang and X. Yang, Lead-free CsCu₂I₃ perovskite nanostructured networks gas sensor for selective detection of trace nitrogen dioxide at room temperature, IEEE Sens. J., 2021, 21, 14677–14684 CAS .
76. Y. Zhuang, W. Yuan, L. Qian, S. Chen and G. Shi, High-performance gas sensors based on a thiocyanate ion-doped organometal halide perovskite, Phys. Chem. Chem. Phys., 2017, 19, 12876–12881 RSC .
77. A. Chizhov, M. Rumyantseva, K. Drozdov, I. Krylov, M. Batuk, J. Hadermann, D. Filatova, N. Khmelevsky, V. Kozlovsky and L. Maltseva, Photoresistive gas sensor based on nanocrystalline ZnO sensitized with colloidal perovskite CsPbBr₃ nanocrystals, Sens. Actuators, B, 2021, 329, 129035 CrossRef CAS .
78. H. Chen, M. Zhang, X. Fu, Z. Fusco, R. Bo, B. Xing, H. T. Nguyen, C. Barugkin, J. Zheng and C. F. J. Lau, Light-activated inorganic CsPbBr₂I perovskite for room-temperature self-powered chemical sensing, Phys. Chem. Chem. Phys., 2019, 21, 24187–24193 RSC .
79. M. Hossain and A. Takshi, Perovskite-based sensing scheme for detecting volatile organic compounds (VOCs) at room temperature, MRS Adv., 2021, 6, 645–649 CrossRef CAS .
80. H. Chen, M. Zhang, R. Bo, C. Barugkin, J. Zheng, Q. Ma, S. Huang, A. W. Ho-Baillie, K. R. Catchpole and A. Tricoli, Superior self-powered room-temperature chemical sensing with light-activated inorganic halides perovskites, Small, 2018, 14, 1702571 CrossRef PubMed .
81. A. Maity, S. Mitra, C. Das, S. Siraj, A. Raychaudhuri and B. Ghosh, Universal sensing of ammonia gas by family of lead halide perovskites based on paper sensors: Experiment and molecular dynamics, Mater. Res. Bull., 2021, 136, 111142 CrossRef CAS .
82. N. Gupta, O. Nanda, R. Grover and K. Saxena, A new inorganic-organic hybrid halide perovskite thin film based ammonia sensor, Org. Electron., 2018, 58, 202–206 CrossRef CAS .
83. A. I. Ayesh, S. Alghamdi, B. Salah, S. Bennett, C. Crean and P. J. Sellin, High sensitivity H₂S gas sensors using lead halide perovskite nanoparticles, Results Phys., 2022, 35, 105333 CrossRef .

This journal is © The Royal Society of Chemistry 2024