Search Results (70)

Improving charge transport in the aggregated state of nanocomposites is challenging due to the large number of defects present at grain boundaries. To enhance the charge transfer and photogenerated carrier extraction of MnO_x nanofibers, a MnO_x/GO (graphene oxide) nanocomposite was prepared. The effects of GO content and bias on the optoelectronic properties were studied. Representative light sources at 405, 650, 780, 808, 980, and 1064 nm were used to examine the photoelectric signals. The results indicate that the MnO_x/GO nanocomposites have photocurrent switching behaviours from the visible region to the NIR (near-infrared) when the amount of GO added is optimised. It was also found that even with zero bias and storage of the nanocomposite sample at room temperature for over 8 years, a good photoelectric signal could still be extracted. This demonstrates that the MnO_x/GO nanocomposites present a strong built-in electric field that drives the directional motion of photogenerated carriers, avoids the photogenerated carrier recombination, and reflect a good photophysical stability. The strength of the built-in electric field is strongly affected by the component ratios of the resulting nanocomposite. The formation of the built-in electric field results from interfacial charge transfer in the nanocomposite. Modulating the charge behaviour of nanocomposites can significantly improve the physicochemical properties of materials when excited by light with different wavelengths and can be used in multidisciplinary applications. Since the recombination of photogenerated electron–hole pairs is the key bottleneck in multidisciplinary fields, this study provides a simple, low-cost method of tailoring defects at grain boundaries in the aggregated state of nanocomposites. These results can be used as a reference for multidisciplinary fields with low energy consumption. Full article

The photocatalytic performance of heterojunctions is often restricted by inferior contact interface and low charge transfer efficiency. In this work, Ti₃C₂O MXene was crafted with AgI/MoS₂ to produce a Z-scheme heterojunction (AgI/MoS₂/Ti₃C₂O). Interfacial electric fields and chemical bonds were proven to exist in the heterojunction. The interfacial electric fields supplied a powerful driving force, and the interfacial Ti-O-Mo bonds served as an atomic-level channel for synergistically expediting the vectorial transfer of photogenerated carriers. As a result, AgI/MoS₂/Ti₃C₂O exhibited significantly improved photocatalytic activity, demonstrating a high H₂O₂ production rate of 700 μmol·g⁻¹·h⁻¹ and a rapid degradation of organic pollutants. Full article

Constructing a heterojunction is considered one of the most effective strategies for enhancing photocatalytic activity. Herein, we employ Ta₃N₅ and tubular graphitic carbon nitride (TCN) to construct a Ta₃N₅/TCN van der Waals heterojunction via electrostatic self-assembly for enhanced photocatalytic H₂ production. SEM and TEM results show that Ta₃N₅ particles (~300 nm in size) are successfully anchored onto the surface of TCN. The light absorption capability of the Ta₃N₅/TCN heterojunction is between those of Ta₃N₅ and TCN. The strong interaction between Ta₃N₅ and TCN with different energy structures (Fermi levels) by van der Waals force renders the formation of an interfacial electric field to drive the separation and transfer of photogenerated charge carriers in the Ta₃N₅/TCN heterojunction, as evidenced by the photoluminescence (PL) and photoelectrochemical (PEC) characterization results. Consequently, the optimal Ta₃N₅/TCN heterojunction exhibits a remarkable H₂ production rate of 12.73 mmol g⁻¹ h⁻¹ under visible light irradiation, which is 3.3 and 16.8 times those of TCN and Ta₃N₅, respectively. Meanwhile, the cyclic experiment demonstrates excellent stability of the Ta₃N₅/TCN heterojunction upon photocatalytic reaction. Notably, the photocatalytic performance of 15-TaN/TCN outperforms the most previously reported CN-based and Ta₃N₅-based heterojunctions for H₂ production. This work provides a new avenue for the rational design of CN-based van der Waals heterojunction photocatalysts with enhanced photocatalytic activity. Full article

Lead halide perovskite quantum dots, also known as perovskite nanocrystals, are considered one of the most promising photovoltaic materials for solar cells due to their outstanding optoelectronic properties and simple preparation techniques. The key factors restricting the photoelectric conversion efficiency of solar cell systems are the separation and transmission performances of charge carriers. Here, femtosecond time-resolved ultrafast spectroscopy was used to measure the interfacial charge transfer dynamics of different sizes of CsPbBr₃ assembled with TiO₂. The effect of perovskite size on the charge transfer is discussed. According to our experimental data analysis, the time constants of the interfacial electron transfer and charge recombination of the assembled systems of CsPbBr₃ and titanium dioxide become larger when the size of the CsPbBr₃ nanocrystals increases. We discuss the physical mechanism by which the size of perovskites affects the rate of charge transfer in detail. We expect that our experimental results provide experimental support for the application of novel quantum dots for solar cell materials. Full article

Highly efficient photocatalysts for solar energy conversion require effective charge carrier separation and rapid interfacial transport kinetics to maximize electron availability. Two-dimensional Ti₃CNT_x, a novel conductive material in the MXene family with exceptional electrical conductivity, has emerged as an ideal electron transfer mediator due to its large specific surface area and abundant active terminal groups. In this work, we strategically integrated the 2D multi-metal sulfide Cu-Zn-In-S (CZIS) with 2D Ti₃CNT_x nanosheets through physical mixture, constructing a heterostructured 2D/2D CZIS/Ti₃CNT_x composite photocatalyst for the hydrogen evolution reaction. The unique architecture significantly accelerates electron migration from CZIS to Ti₃CNT_x, while synergistically promoting the spatial separation and directional transfer of photogenerated electron–hole pairs (e⁻/h⁺). When the hydrogen evolution reaction is carried out under identical conditions, the hydrogen yield rate is 4.3 mmol g⁻¹ h⁻¹ with pristine CZIS but is improved dramatically to 14.3 mmol g⁻¹ h⁻¹ when the composite containing an adequate amount of 2D Ti₃CNT_x is used. This study offers new insight into the rational design and controllable synthesis of Ti₃CNT_x-based composite photocatalytic systems for efficient photocatalytic hydrogen production. Full article

Nanomaterials with large specific surface area (SSA) have emerged as pivotal platforms for energy storage and environmental remediation, primarily due to their enhanced active site exposure, improved mass transport capabilities, and superior interfacial reactivity. Among them, polymeric carbon nitride (g-C₃N₄) has garnered significant attention in energy and environmental applications owing to its visible-light-responsive bandgap (~2.7 eV), exceptional thermal/chemical stability, and earth-abundant composition. However, the practical performance of g-C₃N₄ is fundamentally constrained by intrinsic limitations, including its inherently low SSA (<20 m²/g via conventional thermal polymerization), rapid recombination of photogenerated carriers, and inefficient charge transfer kinetics. Notably, the theoretical SSA of g-C₃N₄ reaches 2500 m²/g, yet achieving this value remains challenging due to strong interlayer van der Waals interactions and structural collapse during synthesis. Recent advances demonstrate that state-of-the-art strategies can elevate its SSA to 50–200 m²/g. To break this surface area barrier, advanced strategies achieve SSA enhancement through three primary pathways: pre-treatment (molecular and supramolecular precursor design), in process (templating and controlled polycondensation), and post-processing (chemical exfoliation and defect engineering). This review systematically examines controllable synthesis methodologies for high-SSA g-C₃N₄, analyzing how SSA amplification intrinsically modulates band structures, extends carrier lifetimes, and boosts catalytic efficiencies. Future research should prioritize synergistic multi-stage engineering to approach the theoretical SSA limit (2500 m²/g) while preserving robust optoelectronic properties. Full article

The photocatalytic reduction of CO₂ into valuable hydrocarbons presents significant potential. In this research, a ZnO/ZnAl₂O₄ composite photocatalyst was synthesized using the hydrothermal method, resulting in a marked enhancement in CO yield—approximately three times greater than that achieved with pure ZnAl₂O₄ nanoparticles. The formation of a Z-scheme heterojunction between ZnO and ZnAl₂O₄ was observed, characterized by low interfacial charge transfer resistance, an abundance of reaction sites, and optimized charge transport pathways. Within this composite, ZnO contributes additional vacancies, thereby increasing active sites and enhancing the separation and migration of photogenerated carriers. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis indicates that ZnAl₂O₄ facilitates the formation of key intermediates, such as *COOH and HCO₃⁻, thus promoting the conversion of CO₂ to CO. This study offers valuable insights into the design of heterogeneous catalysts with diverse active components to enhance the performance of CO₂ photocatalytic reduction through synergistic effects. Full article

To extend the spectral utilisation of In₂S₃, an In₂S₃/C₃N₄ nanocomposite was prepared. The effects of different sulphur sources, electrodes, and bias voltages on the optoelectronic performance were examined. Photoelectric properties in response to light sources with wavelengths of 405, 532, 650, 780, 808, 980, and 1064 nm were investigated using Au electrodes and the carbon electrodes with 5B pencil drawings. This study shows that the aggregation states of the In₂S₃/C₃N₄ nanocomposite possess photocurrent switching responses in the broadband region of the light spectrum. Combining two types of partially visible light-absorbing material extends utilisation to the near-infrared region. Impurities or defects embody an electron-donating effect. Since the energy levels of defects or impurities with an electron-donating effect are close to the conduction band, low-energy lights (especially NIR) can be utilised. The non-equilibrium carrier concentration (photogenerated electrons) of the nanocomposites increases significantly under NIR photoexcitation conditions. Thus, photoconductive behaviour is manifested. A good photoelectric signal was still measured when zero bias was applied. This demonstrates self-powered photoelectric response characteristics. Different sulphur sources significantly affect the photoelectric performance, suggesting that they create different defects that affect charge transport and base current noise. It is believed that interfacial interactions in the In₂S₃/C₃N₄ nanocomposite create a built-in electric field that enhances the separation and transfer of electrons and holes produced by light stimulation. The presence of the built-in electric field also leads to energy band bending, which facilitates the utilisation of the light with longer wavelengths. This study provides a reference for multidisciplinary applications. Full article

Photocatalytic hydrogen (H₂) production offers a promising solution to energy shortages and environmental challenges by converting solar energy into chemical energy. Hydrogen, as a versatile energy carrier, can be generated through photocatalysis under sunlight or via electrolysis powered by solar or wind energy. However, the advancement of photocatalysis is hindered by the limited availability of effective visible light-responsive semiconductors and the challenges of charge separation and transport. To address these issues, researchers are focusing on the development of novel nanostructured semiconductors and composite materials that can enhance photocatalytic performance. In this paper, we provide an overview of the advanced photocatalytic materials prepared so far that can be activated by sunlight, and their efficiency in H₂ production. One of the key strategies in this research area concerns improving the separation and transfer of electron–hole pairs generated by light, which can significantly boost H₂ production. Advanced hybrid materials, such as organic–inorganic hybrid composites consisting of a combination of polymers with metal oxide photocatalysts, and the creation of heterojunctions, are seen as effective methods to improve charge separation and interfacial interactions. The development of Schottky heterojunctions, Z-type heterojunctions, p–n heterojunctions from nanostructures, and the incorporation of nonmetallic atoms have proven to reduce photocorrosion and enhance photocatalytic efficiency. Despite these advancements, designing efficient semiconductor-based heterojunctions at the atomic scale remains a significant challenge for the realization of large-scale photocatalytic H₂ production. In this review, state-of-the-art advancements in photocatalytic hydrogen production are presented and discussed in detail, with a focus on photocatalytic nanostructures, heterojunctions and hybrid composites. Full article

Owing to global energy demands and climate change resulting from fossil fuel use, technologies capable of converting greenhouse gases into renewable energy resources are needed. One such technology is photocatalytic CO₂ reduction, which utilises solar energy to transform CO₂ into value-added hydrocarbons. However, the application of photocatalytic CO₂ reduction is limited by the inefficiency of existing photocatalysts. In this study, we developed a nitrogen-deficient g-C₃N₄-confined PtCu dual-atom catalyst (PtCu/V_N-C₃N₄) for photocatalytic CO₂ reduction. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure spectroscopy confirmed the atomic-level anchoring of PtCu pairs onto the nitrogen-vacancy-rich g-C₃N₄ nanosheets. The optimised PtCu/V_N-C₃N₄ exhibited superior photocatalytic performance, with CO and CH₄ evolution rates of 13.3 µmol/g/h and 2.5 µmol/g/h, respectively, under visible-light irradiation. Mechanistic investigations revealed that CO₂ molecules were preferentially adsorbed onto the PtCu dual sites, initiating a stepwise reduction pathway. In situ diffuse reflectance infrared Fourier-transform spectroscopy identified the formation of a key intermediate (HCOO*), whereas interfacial wettability studies demonstrated efficient H₂O adsorption on PtCu sites, providing essential proton sources for CO₂ protonation. Photoelectrochemical characterisation further confirmed the enhanced charge-transfer kinetics in PtCu/V_N-C₃N₄, which were attributed to the synergistic interplay between the nitrogen vacancies and dual-atom sites. Notably, the dual-active-site architecture minimised the competitive adsorption between CO₂ and H₂O molecules, thereby optimising the surface reaction pathways. This study establishes a rational strategy for designing atomically precise dual-atom catalysts through defect engineering, achieving concurrent improvements in activity, selectivity, and charge carrier utilisation for solar-driven CO₂ conversion. Full article

Nano-titanium dioxide (TiO₂) is currently the most widely studied photocatalyst. However, its rapid recombination of photogenerated carriers and narrow range of light absorption have limited its development. Crystal form regulation and polymer modification are important means for improving the photocatalytic activity of single-phase materials. In this paper, TiO₂ materials of different crystal forms were prepared by changing the synthesis conditions, and they were compounded with trimesoyl chloride–melamine polymers (TMPs) by the hydrothermal synthesis method. Then, their photocatalytic performance was evaluated by degrading methylene blue (MB) under visible light. The mechanisms of influence of TiO₂ crystal form on the photocatalytic activity of TiO₂-TMP were explored by combining characterization and theoretical calculation. The results showed that the TiO₂ crystal form, through interface interaction, the built-in electric field intensity of the heterojunction, and active sites, affected the interface charge separation and transfer, thereby influencing the photocatalytic activity of TiO₂-TMP. In the 4T-TMP photocatalytic system, the degradation rate of MB was the highest. These studies provide theoretical support for understanding the structure–property relationship of the interfacial electronic coupling between TiO₂ crystal forms and TMP, as well as for developing more efficient catalysts for pollutant degradation. Full article

Two-dimensional (2D) van der Waals materials have been actively investigated for broadband, high-sensitivity, low-power-consumption photodetection owing to their highly customizable band structures and fast interfacial charge transfers. Studying photocurrent generation mechanisms provides insights into charge carrier dynamics in WSe₂-based detectors, linking spatial factors (e.g., photocurrent generation/collection) with interfacial band alignment. Here, we employ scanning photocurrent microscopy to spatially resolve the processes of photocurrent generation and collection in WSe₂-based composite structures. Photocurrent polarity and magnitude at interface reflects interfacial band alignment and potential gradients at metal–WSe₂ and WSe₂–In₂Se₃ junctions. Strong electric fields at metal–WSe₂ interfaces drive more efficient electron–hole separation and yield higher photocurrents, compared with WSe₂–In₂Se₃ interfaces. The photodetector exhibits broadband detection capabilities from visible to infrared light, achieving a high responsivity of 17.7 A/W and an excellent detectivity of 3.7 × 10¹² Jones, as well as fast response times of <113 µs. Furthermore, object imaging with a resolution better than 0.5 mm was successfully demonstrated, highlighting the potential of this photoresponse for practical imaging applications. This work reveals that photocurrent is distributed with a clear dependence on device configuration, offering a new avenue for optimizing 2D material-based photoelectric devices. Full article

This study investigates the photocatalytic degradation of methylene blue (MB) using strontium-doped SnO₂ nanofibers synthesized via electrospinning. The 1% Sr-doped SnO₂ nanofibers exhibited remarkable photocatalytic activity, achieving 84.74% MB degradation under visible light irradiation, substantially outperforming both undoped SnO₂ nanofibers (61%) and the same catalyst under UV light (69%) under identical experimental conditions. Comprehensive electrochemical investigations revealed that Sr doping fundamentally transformed interfacial charge transfer kinetics, with 1% Sr-doped nanofibers exhibiting a remarkable three-fold decrease in charge transfer resistance (404 Ω compared to 1350 Ω for undoped samples), a dramatic enhancement in charge carrier density (5.17 × 10²² versus 9.24 × 10¹⁹ for undoped samples), and an approximately eight-fold increase in diffusion coefficient (8.78 × 10⁻¹⁰ versus 1.13 × 10⁻¹⁰ cm²s⁻¹). These electrochemical improvements were corroborated by comprehensive structural characterization, which demonstrated that strategic Sr incorporation induced beneficial oxygen vacancies, reduced crystallite size, increased microstrain, and enhanced dislocation density, collectively contributing to superior surface reactivity and accelerated photocatalytic mechanisms. This work establishes a quantitative correlation between electrochemical characteristics and photocatalytic activity in Sr-doped SnO₂ nanofibers, revealing the fundamental mechanisms that transform the SnO₂ nanostructure from UV-dependent to efficient visible light-driven catalysts for organic pollutant degradation. Full article

CO₂ photoreduction technology offers significant potential for addressing energy and environmental challenges, though its practical application is hindered by insufficient photo-absorption and rapid carrier recombination. Herein, we constructed the WO₃/In₂S₃ S-scheme heterojunction through hydrothermal assembly of two-dimensional WO₃ nanosheets and scale-like In₂S₃ nanoflakes. Systematic characterization via XRD, XPS, SEM, and TEM verified the successful preparation of hierarchical nanostructures with optimized interfacial contact in the WO₃/In₂S₃ composites. UV-Vis DRS analysis showed that the photo-absorption range of the catalyst was significantly widened. Photoelectrochemical investigations (EIS, TPR, PL, and LSV) revealed enhanced carrier separation efficiency and reduced recombination kinetics in the heterojunction system. The optimized WO₃/In₂S₃ (WI-60) catalyst had a CO evolution efficiency of 55.14 μmol·g⁻¹ under the UV-Vis light, representing a 3.9-fold enhancement over the pure In₂S₃ (14.08 μmol·g⁻¹). Mechanistic studies through the XPS and band-structure analysis confirmed the establishment of an S-scheme carrier’ transfer pathway, which simultaneously preserved strong redox potentials and promoted the separation process of carriers. This research provides a validated strategy for developing efficient S-scheme photocatalytic systems for solar fuel generation. Full article

Organic semiconductors have garnered significant interest owing to their low cost, flexibility, and suitability for large-area electronics, making them vital for burgeoning fields such as flexible electronics, wearable devices, and green energy technologies. The performance of organic electronic devices is crucially determined by their interfacial electronic structure. Specifically, interfacial phenomena such as band bending significantly influence carrier injection, transport, and recombination, making their control paramount for enhancing device performance. This review investigates the interplay among molecular orientation, interfacial charge transfer, and interfacial chemical reactions as the primary drivers of interface band bending. Furthermore, it critically examines effective strategies for optimizing interfacial properties via interface engineering, focusing on interlayer insertion and template layer methods. The review concludes with a summary and outlook, emphasizing the integration of interface design with material development and device architecture to realize next-generation, high-performance organic electronic devices exhibiting improved efficiency and stability. Full article