Engineered s-SWCNT network/a-Ga₂O₃ heterointerface for enhanced deep ultraviolet photodetection†

Zhenwei Guo^a, Yisong Chen^b, Haoming Wei*^a, Dayong Jiang*^a, Man Zhao^a and Qianli Huang *^b
aSchool of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, P. R. China. E-mail: whm@cust.edu.cn; jiangdy@cust.edu.cn
^bState Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, P. R. China. E-mail: huangqianli@csu.edu.cn

First published on 17th July 2025

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Qianli Huang

Qianli Huang is currently an associate professor at the State Key Laboratory of Powder Metallurgy at Central South University. He obtained his BE degree in engineering in 2012 at Central South University (China) and received his PhD degree in engineering in 2017 from Tsinghua University (China). He then worked as a research fellow in Prof. Yong Liu's group at Central South University. His research interests focus on inorganic materials for sensing, biomedical and catalytic applications.

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1. Introduction

Deep-ultraviolet (DUV) photodetectors are gaining prominence across diverse sectors, including flame detection, ozone layer monitoring, water purification, biomedical analysis, and secure optical communication. The escalating demands of these applications drive the need for DUV detectors with superior performance, stability, cost-effectiveness, and resilience to harsh environments.^1–3 Wide-bandgap semiconductors (WBGSs), particularly gallium oxide (Ga₂O₃), have emerged as compelling candidates for high-performance solar-blind/DUV photodetectors due to their ultra-wide bandgap (∼4.9 eV), high breakdown field strength, and exceptional thermal/chemical stability.^4–6 However, the inherent limitations of Ga₂O₃, such as low carrier mobility and significant electron–hole recombination, severely curtail its optoelectronic conversion efficiency, resulting in diminished responsivity and external quantum efficiency (EQE), thus impeding its suitability for advanced applications.^7–9 Consequently, devising innovative strategies to enhance carrier separation and transport in Ga₂O₃-based DUV photodetectors substantially represents a pivotal challenge and active area of investigation.

Heterojunction engineering is a widely adopted approach to circumvent these constraints.^10–12 By integrating a wide-bandgap light-absorbing layer with a material exhibiting superior carrier transport properties, efficient electron–hole separation and accelerated carrier transport to the electrodes can be achieved, thereby boosting device performance. Various materials have been explored in conjunction with Ga₂O₃ to construct heterojunction DUV photodetectors.^13–15 An ideal heterojunction partner should possess a compatible band alignment (e.g., Type-I or Type-II) conducive to carrier separation and demonstrate high carrier mobility and compatibility with Ga₂O₃ processing techniques, ideally with low-cost and scalable fabrication. Semiconducting single-walled carbon nanotubes (s-SWCNTs) present a promising avenue, characterized by their one-dimensional structure, exceptional carrier mobility, mechanical flexibility, and solution-processability for thin-film deposition.^16–18 Integrating s-SWCNTs with Ga₂O₃ holds the potential to realize a novel and efficient DUV photodetector. Despite this potential, research remains limited regarding the fabrication of high-quality s-SWCNT/Ga₂O₃ heterojunctions via a facile and scalable method, along with in-depth investigations into the interfacial band alignment and its mechanism.

To address this challenge, we report an s-SWCNT/amorphous Ga₂O₃ (a-Ga₂O₃) heterojunction DUV photodetector fabricated using a combination of spin-coating (for s-SWCNTs) and magnetron sputtering (for a-Ga₂O₃). We employed a metal–semiconductor–metal (MSM) device structure with interdigitated electrodes positioned beneath the s-SWCNT layer to maximize its carrier collection capability. More critically, we demonstrate that this unique architecture engenders a Type-I band alignment, facilitating DUV-generated carrier creation in a-Ga₂O₃ and subsequent injection into the s-SWCNTs while preserving the s-SWCNT network's function as an efficient and continuous charge transport channel. The s-SWCNT/a-Ga₂O₃ heterojunction device exhibits stable photoresponse within the 230–280 nm DUV spectrum and a peak responsivity of 1.4 A W⁻¹, surpassing that of bare a-Ga₂O₃ devices fabricated under identical conditions. This work not only highlights the promise of s-SWCNT/a-Ga₂O₃ heterojunctions for high-performance DUV detection but also offers a simple, low-cost, and scalable approach for developing high-performance optoelectronic devices based on carbon nanomaterial/wide-bandgap oxide heterostructures. A detailed account of the material preparation, structural characterization, optoelectronic performance assessment, and a thorough discussion of the underlying mechanisms are presented in the following sections.

2. Experimental

Detailed experimental procedures, materials, and equipment specifications can be found in the ESI.† The essential fabrication steps for the s-SWCNT/a-Ga₂O₃ heterostructure devices are briefly outlined as follows: initially, s-SWCNTs dispersed in toluene (concentration ∼20 μg mL⁻¹, the semiconductor purity >99.9%, sourced from SINANO) were deposited onto glass substrates pre-patterned with gold interdigitated electrodes via a multi-step spin-coating procedure (final speeds controlled within the 2000–5000 rpm range, see ESI† for program details), forming s-SWCNT networks of varying densities. Following a brief thermal treatment (100 °C, 1 min, air), a-Ga₂O₃ thin films were subsequently deposited directly onto the s-SWCNT network films via radio frequency (RF) magnetron sputtering at room temperature under an argon atmosphere (40 sccm Ar, O₂-free) using a power of 120 W, thereby constructing the crucial s-SWCNT/a-Ga₂O₃ heterointerface. The morphology, structure, composition, and optical/optoelectronic properties of the resulting films were systematically characterized using standard techniques (detailed in the ESI†).

3. Results and discussion

To construct an s-SWCNT/a-Ga₂O₃ heterojunction with enhanced DUV photoresponsivity while simultaneously investigating its fundamental charge transfer and separation mechanisms, we devised and implemented a distinct fabrication strategy. This approach integrates spin-coating for the s-SWCNT network deposition with magnetron sputtering for the subsequent a-Ga₂O₃ thin film growth. The procedural schematic for this heterostructure fabrication is clearly illustrated in Fig. 1. Initially, s-SWCNT thin films of varying densities were formed on glass substrates pre-patterned with gold interdigitated electrodes by carefully controlling the spin-coating speed. During spin-coating, the s-SWCNT dispersion is uniformly applied over the substrate including the gold interdigitated electrodes. Due to the hydrophilic substrate surface (Fig. S1 and S2†) and optimized spin-coating parameters, s-SWCNTs preferentially form uniform networks on the whole interdigitated electrode area with minimal adhesion on the electrode fingers, preventing unintended coverage and ensuring proper device operation. Following a brief thermal treatment to evaporate the solvent, a layer of a-Ga₂O₃ was subsequently deposited onto the s-SWCNT film via RF magnetron sputtering. This precisely controlled process was designed to establish a specific s-SWCNT/a-Ga₂O₃ interfacial structure, which serves as the foundational element for achieving the subsequent high-performance photodetection.

To ascertain the microstructural characteristics of the fabricated materials, detailed morphological characterizations were undertaken. Scanning electron microscopy (SEM) images vividly revealed that the underlying s-SWCNT film presents a typical interconnected network structure, composed of carbon nanotubes with diameters ranging approximately from 5 to 10 nm (Fig. 2(a) and (b)). This continuous network morphology furnishes potential high-efficiency pathways for carrier transport. The overlying a-Ga₂O₃ film exhibited a dense and uniform surface morphology (Fig. 2(c)). Cross-sectional SEM analysis indicated an a-Ga₂O₃ film thickness of approximately 620 nm (Fig. 2(d)), ensuring effective absorption of DUV light. Atomic force microscopy (AFM) further corroborated the continuous network structure of the s-SWCNT film and its relatively low surface roughness (R_q = 0.845 nm, Fig. 2(e) and (f)). This smooth surface topography is advantageous for the uniform deposition of the subsequent a-Ga₂O₃ layer and the formation of a high-quality interfacial contact. Collectively, this morphological evidence provides preliminary confirmation of the successful construction of the intended s-SWCNT network/a-Ga₂O₃ composite structure.

Following fabrication, the as-prepared material was thoroughly characterized using X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, and X-ray photoelectron spectroscopy (XPS) to determine its phase properties, optical characteristics, and surface chemistry, respectively. XRD patterns acquired from both the pristine a-Ga₂O₃ film and the s-SWCNT/a-Ga₂O₃ composite films displayed only a broad diffraction hump between 15–40°, attributed to the amorphous glass substrate (Fig. 3(a)). This observation confirms the amorphous nature of the sputter-deposited Ga₂O₃ layer. Notably, characteristic diffraction peaks corresponding to s-SWCNTs were absent in the composite film spectra. This is ascribed to the complete attenuation of the signal from the underlying s-SWCNTs by the relatively thick (620 nm) and dense a-Ga₂O₃ overlayer, indirectly testifying to the structural integrity and full coverage. UV-Vis absorption spectroscopy (Fig. 3(b)) demonstrated that, compared to the pure a-Ga₂O₃ film, all s-SWCNT/a-Ga₂O₃ composite films exhibited enhanced absorption in the DUV region. This enhancement is attributed to the improved light-harvesting efficiency facilitated by the incorporated s-SWCNT network. Intriguingly, the absorption intensity of the composite films systematically decreased with increasing s-SWCNT spin-coating speed (i.e., decreasing network density). Furthermore, their optical bandgaps, estimated from Tauc plots (Fig. 3(b) inset), displayed a degree of tunability dependent on the spin-coating speed (ranging between approximately 0.15–0.25 eV variation relative to the 4.54 eV bandgap of pure a-Ga₂O₃ (ref. 19)). This tunability likely stems from the influence of interfacial interactions between s-SWCNTs and a-Ga₂O₃ on the overall electronic structure. XPS analysis (Fig. 3(c)) confirmed the surface composition, dominated by Ga and O elements. Analysis of the Ga 2p core levels (ΔE = 27 eV between Ga 2p_1/2 at 1146.08 eV and Ga 2p_3/2 at 1119.08 eV) indicated that Ga exists predominantly in the Ga₂O₃ chemical state. Deconvolution of the O 1s spectrum (Fig. 3(d)) allowed for the identification of distinct oxygen species: surface-adsorbed oxygen/hydroxyl groups (O(I), 532.4 eV), oxygen vacancies (O(II), 531.3 eV), and lattice oxygen (O(III), 530.7 eV).^20,21 The O 1s spectra of the pure a-Ga₂O₃ and the s-SWCNT/a-Ga₂O₃ composite films were remarkably similar, showing no significant deviations beyond normal experimental variance. This similarity arises because the limited probing depth of XPS predominantly samples the near-surface region of the thick a-Ga₂O₃ overlayer, thus reaffirming the substantial thickness and denseness of the a-Ga₂O₃ coating. These detailed physical property characterizations establish a foundation for understanding the subsequent optoelectronic device performance in relation to the heterostructure architecture.

Leveraging the fabricated heterostructures, photodetectors were constructed, and their performance was systematically evaluated to validate the enhancing effect of the s-SWCNT/a-Ga₂O₃ interface on the photoresponse. As illustrated in Fig. 4(a), compared to the device based on pure a-Ga₂O₃ (PD-1), the heterojunction device incorporating s-SWCNTs (PD-2) exhibited a dramatically enhanced responsivity under 260 nm DUV illumination. The responsivity R can be determined by the following equation:⁴

where I_ph and I_dark represent the photocurrent and dark current, P_optical is the incident optical power density, and A is the effective area under illumination, which is 3.555 × 10⁻² cm² for our devices. R is usually measured in ampere per watt (A W⁻¹). At a bias voltage of 20 V, the peak responsivity for PD-2 reached a maximum of 1.4 A W⁻¹, representing a remarkable 280-fold improvement over PD-1 (0.005 A W⁻¹), as shown in Fig. 4(a) and the inset. This responsivity value not only substantially exceeds that of the pure a-Ga₂O₃ device but also compares favorably with many reported Ga₂O₃-based DUV photodetectors, and the detailed parameter comparison can be found in Table S1.† It is crucial to acknowledge, however, that a direct tabular comparison of photodetector performance metrics and testing conditions across various literature sources may not fully reflect their true relative merits. This is primarily because the experimental conditions employed in different studies often vary significantly. Therefore, readers are advised to exercise caution and critical judgment when interpreting such comparative data. The responsivity of PD-2 was observed to initially increase with the s-SWCNT spin-coating speed, reaching an optimal value before declining at higher rates. This trend likely reflects competing factors: moderately higher speeds appear to promote the formation of more uniform, higher-quality s-SWCNT films, which is advantageous for heterojunction interface formation and subsequent carrier transport. Conversely, excessively high speeds (e.g., 5000 rpm) result in insufficient s-SWCNT deposition to maintain a continuous conductive network, thereby impairing overall optoelectronic performance. The spectral response of the devices also demonstrated a clear dependence on the applied bias voltage. Fig. 4(b) displays the spectral response characteristics of a typical PD-2 device as a function of bias voltage, showing that responsivity increases with increasing bias applied across the MSM structure. Furthermore, the spectral response is strongly peaked in the DUV region with negligible response to visible light, yielding a commendable UV/visible rejection ratio of 116. Additionally, the current–voltage (I–V) characteristics (Fig. 4(c)) displayed typical rectifying behavior, with a rectification ratio reaching 24 under illumination. The rectifying behavior evident in the I–V characteristics originates from an inherent asymmetry in the contacts between the s-SWCNT layer and the electrodes. This asymmetry is a direct consequence of the spin-coating fabrication method: despite its widespread use, this technique is prone to creating subtle, microscopic variations in the local density and arrangement of the nanotubes across the substrate. As a result, the two metal–semiconductor junctions within the MSM device structure are not perfectly identical. This structural non-uniformity leads to the formation of dissimilar Schottky barriers at each respective interface, which in turn gives rise to the observed diode-like rectifying effect.²² Compared to PD-1, the photocurrent in PD-2 was enhanced by approximately 2–3 orders of magnitude (Fig. 4(d)), significantly outweighing any increase in dark current. This pronounced enhancement is directly attributed to the dual role of the s-SWCNT network acting as an efficient charge transport conduit and the heterojunction interface facilitating effective photogenerated carrier separation.

The EQE value describes the ability of a photodetector to convert the input light to an output electrical signal, which is the figure-of-merit in gallium oxide-based photodetectors and can be expressed as:⁴

where R, h, c, e, and λ are the responsivity, Planck's constant, speed of light, electronic charge, and the wavelength of the incident light, respectively. The calculated EQE data (Fig. 4(e)) provide further compelling evidence of the advantage introduced by the heterointerface: the PD-2 device exhibiting the highest responsivity in Fig. 4(a) achieved a maximum EQE of 671% at 20 V bias voltage, whereas PD-1 yielded only 2.4% under the same conditions (note: due to the high photoresponse of PD-2 devices prepared with 3000–5000 rpm spin-coating, EQE values at higher biases exceeded the instrument's measurement range; hence, only data within the measurable range is presented). Such significant performance enhancements provide strong evidence for the exceptional capability of our designed s-SWCNT/a-Ga₂O₃ heterostructure in promoting photogenerated carrier separation and transport. Further discussion is warranted regarding the frequent observation in the literature that an enhancement of the EQE in Ga₂O₃-based photodetectors is commonly attributed to the persistent photoconductivity (PPC) effect.^23–25 This phenomenon extends the carrier lifetime, which, while beneficial for increasing photocurrent, simultaneously leads to an elevated dark current and a delayed response speed. Our devices exhibit analogous behavior, as evidenced by the current–time (I–t) response curves presented in Fig. S4,† which confirm the presence of PPC in this system. However, the great improvement in EQE observed in PD-2 relative to PD-1 cannot be ascribed to this effect. This conclusion is supported by the fact that the a-Ga₂O₃ thin films in both devices were fabricated via an identical RF magnetron sputtering process, and XPS characterization also substantiates the compositional uniformity of the films (Fig. 3(c) and (d)), particularly with respect to the oxygen vacancy concentration—commonly regarded as a principal driver of PPC^26–28—which remains comparable between the two types of devices. Accordingly, a probable subject for our future investigation involves devising strategies to enhance photoresponse efficiency while mitigating the adverse effects associated with PPC. In other words, achieving an optimal balance and trade-off between these competing factors remains a topic worth studying. Moreover, the intrinsic properties of PPC could be further harnessed to develop other advanced device applications, particularly in the realms of optoelectronic synapses and memristors,^29–31 thereby expanding the functional versatility of these materials.

In addition to responsivity and external quantum efficiency, the specific detectivity (D*) is also an important parameter to characterize how well a weak signal can be detected compared to the noise. D* is expressed by the following equation:⁴

where A is the effective area under illumination, e is the electronic charge, I_dark is the dark current and R is the responsivity in A W⁻¹. Alternatively, D* can be also expressed as the inverse of noise equivalent power (NEP). Fig. 4(f) presents a comparative analysis of the specific detectivity and noise equivalent power of PD-1 and PD-2 devices under 260 nm illumination, where PD-2 samples were fabricated using varying spin-coating speeds and subjected to different bias voltages. The results demonstrate that PD-2 devices exhibiting higher responsivity also possess superior noise characteristics. Specifically, PD-2 fabricated at a spin-coating speed of 4000 rpm achieved a D* of 2.99 × 10¹¹ Jones and an NEP of 6.29 × 10⁻¹³ W Hz^−1/2, as shown in the upper part of Fig. 4(f). Besides, in alignment with the observed trend for responsivity, the typical D* of PD-2 devices increases, while the NEP decreases, with increasing applied bias voltage, as presented in the lower part of Fig. 4(f). This feature highlights the device's controllable response and its robust operational stability under varying electrical conditions.

It is important to note that the magnitude of the noise characteristics is on par with levels reported for other photodetectors based on Ga₂O₃ heterojunctions with various nanomaterials,^32–34 however, the device has not yet reached a state-of-the-art performance level. This limitation is primarily attributed to a relatively high dark current—a consequence of the unsuppressed PPC effect, as discussed earlier—which is compounded by the inherently more efficient charge transport pathways typical of nanomaterials. Nevertheless, this does not diminish the novelty of our proposed s-SWCNT/a-Ga₂O₃ heterointerface, whose effectiveness in promoting carrier separation and enhancing responsivity has been demonstrated unequivocally. Moreover, these findings illuminate a clear path forward for prospective research: a focused effort on optimizing the device fabrication protocols and architectural design of the s-SWCNT/a-Ga₂O₃ system is required to unlock further improvements in its overall performance.

To gain deeper insights into the underlying physical mechanisms governing the performance enhancement, specifically the charge transfer characteristics at the s-SWCNT/a-Ga₂O₃ interface, Raman spectroscopy and photoluminescence (PL) studies were conducted. The Raman spectrum (Fig. 5(a)) displays the characteristic features of s-SWCNTs: the D-band (1338 cm⁻¹), the G-band (split into G⁻ at 1568 cm⁻¹ and G⁺ at 1591 cm⁻¹), and the 2D-band (2674 cm⁻¹).³⁵ Crucially, a distinct redshift of approximately 2 cm⁻¹ was observed for the G-band in the s-SWCNT/a-Ga₂O₃ composite sample compared to the pristine s-SWCNTs (Fig. 5(a) inset). Given that the G-band frequency is highly sensitive to charge transfer between carbon nanotubes, this observed redshift serves as direct evidence for static electron transfer from the n-type a-Ga₂O₃ to the p-type s-SWCNTs, confirming the formation of an intimate electronically interacting interface, i.e., the successful construction of the heterojunction.³⁶ PL spectroscopy provided further insights into the band alignment type and carrier dynamics at the heterojunction. As shown in Fig. 5(b), under identical excitation conditions, the s-SWCNT/a-Ga₂O₃ heterojunction film exhibited significantly enhanced PL intensity compared to the pure a-Ga₂O₃ film. Concurrently, time-resolved photoluminescence (TRPL) measurements revealed a substantially shorter fluorescence lifetime for the heterojunction sample compared to pure a-Ga₂O₃ (Fig. 5(c)), indicating fluorescence quenching. This seemingly paradoxical observation of enhanced PL intensity coupled with lifetime quenching can be rationally explained within the framework of a Type-I heterojunction.^37–39 Upon photon absorption in a-Ga₂O₃ and generation of electron–hole pairs, the favorable band alignment drives the efficient transfer of both electrons and holes to the narrower bandgap s-SWCNT layer. This influx increases the carrier concentration within the s-SWCNT layer, potentially enhancing its intrinsic emission or interface-related recombination emission. Simultaneously, this efficient interfacial transfer process provides a fast non-radiative decay channel (transfer to SWCNTs or recombination at the interface), leading to an overall reduction (quenching) of the fluorescence lifetime. This combined PL behavior strongly supports the formation of a Type-I band alignment at the s-SWCNT/a-Ga₂O₃ interface.

Based on the collective experimental evidence, we propose an energy band diagram for the s-SWCNT/a-Ga₂O₃ heterojunction to elucidate its operational mechanism (Fig. 6). It is known that p-type s-SWCNTs possess conduction and valence band edge positions at approximately −4.15 eV and −4.8 eV, respectively.^40,41 For n-type a-Ga₂O₃, the conduction band minimum (CBM) is around −4.0 eV,⁴² and the valence band maximum (VBM) is near −8.54 eV (derived from E_g ≈ 4.54 eV). Upon contact, owing to differences in work functions and subsequent band bending, a distinct Type-I heterojunction is formed, where both the conduction and valence bands of the s-SWCNTs lie energetically within the bandgap of a-Ga₂O₃ (Fig. 6(a)). When the device is illuminated with DUV light (e.g., 260 nm), photons with energy exceeding the a-Ga₂O₃ bandgap are primarily absorbed within the a-Ga₂O₃ layer, generating copious electron–hole pairs. Driven by the favorable potential gradient established by the Type-I band alignment, both photogenerated electrons and holes are efficiently transferred from the a-Ga₂O₃ layer into the s-SWCNT network layer (Fig. 6(b)). Subsequently, these separated carriers are transported along the highly conductive s-SWCNT network and are ultimately collected by the electrodes, resulting in the significantly enhanced photocurrent observed experimentally.

In summary, this study successfully demonstrates the fabrication of a unique s-SWCNT/a-Ga₂O₃ heterostructure through a combination of spin-coating s-SWCNT networks and sputtering a-Ga₂O₃ thin films. Morphological characterization (Fig. 2) and analysis of physical properties (Fig. 3) confirmed the formation of the intended structure. Especially, optoelectronic performance evaluations (Fig. 4) revealed that the heterostructure device exhibited a 280-fold enhancement in responsivity and an impressive EQE of up to 671% compared to control devices based on pure a-Ga₂O₃, showcasing outstanding DUV photodetection capabilities as well as reasonable signal-to-noise ratio properties. In-depth mechanistic investigations, particularly Raman spectroscopy indicating interfacial charge transfer (Fig. 5(a)) and PL/TRPL studies suggesting Type-I band alignment coupled with effective carrier separation (Fig. 5(b) and (c)), pinpointed the origins of this substantial performance improvement. The proposed energy band model (Fig. 6) provides a coherent explanation: the unique interface forms a Type-I heterojunction that promotes efficient transfer of photogenerated carriers from a-Ga₂O₃ to s-SWCNTs, while the highly conductive s-SWCNT network ensures their productive transport. The synergy between these two factors dramatically enhances carrier separation and collection efficiencies, thereby effectively addressing the fundamental mechanisms of charge transfer and separation at this interface under DUV excitation.

4. Conclusion

In conclusion, this work not only presents a high-performance DUV photodetector but, more importantly, elucidates and validates an effective strategy for boosting optoelectronic device performance by constructing Type-I heterojunctions between carbon nanotubes and wide-bandgap oxides. Furthermore, the methodological approach employed herein, integrating scalable solution-based spin-coating with standard sputtering techniques, offers a versatile and highly promising strategy for the future low-cost, large-scale fabrication of high-performance narrow-bandgap/wide-bandgap heterostructures and their broad application across fields such as optoelectronics and photocatalysis.

Data availability

The data supporting this article have been included as part of the ESI.†

Author contributions

Z. Guo: investigation, visualization, writing – original draft, and formal analysis. Y. Chen: investigation, validation, and formal analysis. H. Wei: conceptualization, funding acquisition, writing – review and editing, and formal analysis. D. Jiang: supervision and formal analysis. M. Zhao: resources, project administration, and formal analysis. Q. Huang: supervision, funding acquisition, writing – review and editing, and formal analysis.

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

The authors are grateful for financial support from Jilin Provincial Scientific and Technological Development Program (Grant No. YDZJ202401562ZYTS), National Natural Science Foundation of China (Grant No. 62274016, 52101295), Key Research and Development Program of Hunan Province of China (Grant No. 2023SK2011), and Outstanding Youth Scientist Foundation of Hunan Province (Grant No. 2023JJ20067).

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Footnote

† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d5ta03615a

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