Search Results (123)

Photoelectrochemical devices have garnered extensive research attention in the field of smart and multifunctional photoelectronics, owing to their lightweight nature, eco-friendliness, and cost-effective manufacturing processes. In this work, Bi₂S₃/Bi₂O₃/TiO₂ heterojunction film was successfully fabricated and functioned as the photoelectrode of photoelectrochemical devices. The designed Bi₂S₃/Bi₂O₃/TiO₂ photoelectrochemical photodetector possesses a broad light detection spectrum ranging from 400 to 900 nm and impressive self-powered characteristics. At 0 V bias, the device exhibits an on/off current ratio of approximately 1.3 × 10⁶. It achieves a commendable detectivity of 5.7 × 10¹³ Jones as subjected to a 0.8 V bias potential, outperforming both bare TiO₂ and Bi₂O₃/TiO₂ photoelectrochemical devices. Moreover, the Bi₂S₃/Bi₂O₃/TiO₂ photoelectrode film shows great promise in pollutant decomposition, achieving nearly 97.7% degradation efficiency within 60 min. The appropriate band energy alignment and the presence of an internal electric field at the interface of the Bi₂S₃/Bi₂O₃/TiO₂ film serve as a potent driving force for the separation and transport of photogenerated carriers. These findings suggest that the Bi₂S₃/Bi₂O₃/TiO₂ heterojunction film could be a viable candidate as a photoelectrode material for the development of high-performance photoelectrochemical optoelectronic devices. 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

This work presents a novel approach to investigating epitaxial GaAsN layers and GaAsN-based p-i-n solar cell structures using light-assisted scanning capacitance microscopy (SCM) and spectroscopy. Due to the technological challenges in growing high-quality GaAsN with controlled nitrogen incorporation, the epitaxial layers often exhibit inhomogeneity in their opto-electrical properties. By combining localized cross-section SCM measurements with wavelength-tunable optical excitation (800–1600 nm), we resolved carrier concentration profiles, internal electric fields, and deep-level transitions across the device structure at a nanoscale resolution. A comparative analysis between electrochemical capacitance–voltage (EC-V) profiling and photoluminescence spectroscopy confirmed multiple localized transitions, attributed to compositional fluctuations and nitrogen-induced defects within GaAsN. The SCM method revealed spatial variations in energy states, including discrete nitrogen-rich regions and gradual variations in the nitrogen content throughout the layer depth, which are not recognizable using standard characterization methods. Our results demonstrate the unique capability of the photo-scanning capacitance microscopy and spectroscopy technique to provide spatially resolved insights into complex dilute nitride structures, offering a universal and accessible tool for semiconductor structures and optoelectronic devices evaluation. Full article

Titanium dioxide (TiO₂) is a wide-bandgap semiconductor material with broad application potential, known for its excellent photocatalytic performance, high chemical stability, low cost, and non-toxicity. These properties make it highly attractive for applications in photovoltaic energy, environmental remediation, and optoelectronic devices. For instance, TiO₂ is widely used as a photocatalyst for hydrogen production via water splitting and for degrading organic pollutants, thanks to its efficient photo-generated electron–hole separation. Additionally, TiO₂ exhibits remarkable performance in dye-sensitized solar cells and photodetectors, providing critical support for advancements in green energy and photoelectric conversion technologies. Boron-doped diamond (BDD) is renowned for its exceptional electrical conductivity, high hardness, wide electrochemical window, and outstanding chemical inertness. These unique characteristics enable its extensive use in fields such as electrochemical analysis, electrocatalysis, sensors, and biomedicine. For example, BDD electrodes exhibit high sensitivity and stability in detecting trace chemicals and pollutants, while also demonstrating excellent performance in electrocatalytic water splitting and industrial wastewater treatment. Its chemical stability and biocompatibility make it an ideal material for biosensors and implantable devices. Research indicates that the combination of TiO₂ nanostructures and BDD into heterostructures can exhibit unexpected optical and electrical performance and transport behavior, opening up new possibilities for photoluminescence and rectifier diode devices. However, applications based on this heterostructure still face challenges, particularly in terms of photodetector, photoelectric emitter, optical modulator, and optical fiber devices under high-temperature conditions. This article explores the potential and prospects of their combined heterostructures in the field of optoelectronic devices such as photodetector, light emitting diode (LED), memory, field effect transistor (FET) and sensing. TiO₂/BDD heterojunction can enhance photoresponsivity and extend the spectral detection range which enables stability in high-temperature and harsh environments due to BDD’s thermal conductivity. This article proposes future research directions and prospects to facilitate the development of TiO₂ nanostructured materials and BDD-based heterostructures, providing a foundation for enhancing photoresponsivity and extending the spectral detection range enables stability in high-temperature and high-frequency optoelectronic devices field. Further research and exploration of optoelectronic devices based on TiO₂-BDD heterostructures hold significant importance, offering new breakthroughs and innovations for the future development of optoelectronic technology. Full article

Over the last decade, polymeric carbon nitrides (PCNs) have received exponentially growing attention as metal-free photocatalytic platforms for green energy generation and environmental remediation. Although PCNs can be easily synthesized from abundant precursors in a powdered form, progress in the field of photoelectrochemical applications requires effective methods for the fabrication of PCN films endowed with suitable mechanical stability and modular chemico-physical properties. In this context, as a proof-of-concept, we report herein on a simple and versatile chemical vapor infiltration (CVI) strategy for one-step PCN growth on porous Ni foam substrates, starting from melamine as a precursor compound. Interestingly, tailoring the reaction temperature enabled to control the condensation degree of PCN films from melem/melon hybrids to melon-like materials, whereas the use of different precursor amounts directly affected the mass and morphology of the obtained deposits. Altogether, such features had a remarkable influence on PCN electrochemical performances towards the oxygen evolution reaction (OER), yielding, for the best performing systems, Tafel slopes as low as ≈65 mV/dec and photocurrent density values of ≈1 mA/cm² at 1.6 V vs. the reversible hydrogen electrode (RHE). 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

Various types of strain, as well as chemical pressure induced by dopants, can effectively tailor the performance of perovskite thin films, including their optical, electrical or photoelectrochemical properties. The control of these functional properties through such engineering techniques is key to fulfilling the application-specific requirements of ferroelectric devices in various fields. Numerous models and experimental data have been published on this subject, especially on ferrite-based ferroelectric materials. Within this paper, the mechanisms of tuning ferroelectric intrinsic properties, such as polarization and ferroelectric domain configurations, through epitaxial strain and doping, as well as the role of these techniques in influencing functional properties such as dielectric and photoelectrochemical ones, are presented. This review examines the significant improvements in dielectric properties and photoelectrochemical efficiency achieved by the strategical control of key functionalities including dielectric losses, domain structures, charge separation and surface reactions in strained/doped ferroelectric thin films, highlighting the advancements and research progress made in this field in recent years. Full article

Two-dimensional nanomaterials (2DNMs) exhibit significant potential for the development of functional and specifically targeted biosensors, owing to their unique planar nanosheet structures and distinct physical and chemical properties. Biomodification and biomimetic synthesis offer green and mild approaches for the fabrication of multifunctional nanohybrids with enhanced catalytic, fluorescent, electronic, and optical properties, thereby expanding their utility in constructing high-performance biosensors. In this review, we present recent advances in the synthesis of 2DNM-based nanohybrids via both biomodification and biomimetic strategies for biosensor applications. We discuss covalent and non-covalent biomodification methods involving various biomolecules, including peptides, proteins, DNA/RNA, enzymes, biopolymers, and bioactive polysaccharides. The engineering of biomolecule–nanomaterial interfaces for the creation of biomodified 2DNM-based nanohybrids is also explored. Furthermore, we summarize the biomimetic synthesis of 2DNM-based bio–nanohybrids through pathways such as bio-templating, biomolecule-directed self-assembly, biomineralization, and biomimetic functional integration. The potential applications of these nanohybrids in diverse biosensing platforms—including colorimetric, surface plasmon resonance, electrochemical, fluorescence, photoelectrochemical, and integrated multimodal biosensors—are introduced and discussed. Finally, we analyze the opportunities and challenges associated with this rapidly developing field. We believe this comprehensive review will provide valuable insights into the biofunctionalization of 2DNMs and guide the rational design of advanced biosensors for diagnostic applications. Full article

Organophosphorus pesticides (OPs), while pivotal for agricultural productivity, pose severe environmental and health risks due to their persistence and bioaccumulation. Existing detection methods, such as chromatography and spectroscopy, face limitations in field adaptability, cost, and operational complexity. To address these challenges, this study introduces a novel dual-mode photoelectrochemical–electrochemical (PEC-EC) sensor based on a Co,N-TiO₂@ZrO₂/3DGH nanocomposite. The sensor synergistically integrates zirconium oxide (ZrO₂) for selective OP capture via phosphate-Zr coordination, cobalt-nitrogen co-doped titanium dioxide (Co,N-TiO₂) for visible-light responsiveness, and a three-dimensional graphene hydrogel (3DGH) for enhanced conductivity. In the PEC mode under light irradiation, OP adsorption induces charge recombination, yielding a logarithmic photocurrent attenuation with a detection limit of 0.058 ng mL⁻¹. Subsequently, the EC mode via square wave voltammetry (SWV) self-validates the results, achieving a detection limit of 0.716 ng mL⁻¹. The dual-mode system demonstrates exceptional reproducibility, long-term stability, and selectivity against common interferents. Parallel measurements revealed <5% inter-mode discrepancy, validating the intrinsic self-checking capability. This portable platform bridges the gap between laboratory-grade accuracy and field-deployable simplicity, offering transformative potential for environmental monitoring and food safety management. Full article

Developing high-efficiency photoelectrodes plays an important role in the photoelectrocatalytic generation of hydrogen peroxide (H₂O₂) in the photoelectrochemical (PEC) water splitting field. In this work, an innovative strategy was proposed, the synergistic photocatalytic production of H₂O₂ using a bidirectional photoanode–photocathode coupling system under visible-light irradiation. Fe₂O₃-Ti, as the photoanode, which was built by way of Fe₂O₃ loaded on Ti-mesh using the hydrothermal-calcination method, was investigated in terms of the suitability of its properties for PEC H₂O₂ production after optimization of the bias voltage, the type of electrolyte solution, and the concentration of the electrolyte. Afterwards, a H-type double-electrode coupling system with an Fe₂O₃-Ti photoanode and a WO₃@Co₂SnO₄ photocathode was established for the bidirectional synergistic production of H₂O₂ under visible-light irradiation. The yield of H₂O₂ reached 919.56 μmol·L⁻¹·h⁻¹ in 2 h over −0.7 V with 1 mol·L⁻¹ of KHCO₃ as the anolyte and 0.1 mol·L⁻¹ Na₂SO₄ as the catholyte (pH = 3). It was inferred that H₂O₂ production on the WO₃@Co₂SnO₄ photocathode was in line with the 2e^- oxygen reduction reaction (ORR) principle, and on the Fe₂O₃-Ti photoanode was in line with the 2e^- water oxidation reaction (WOR) rule, or it was indirectly promoted by the electrolyte solution KHCO₃. This work provides an innovative idea and a reference for anode–cathode double coupling systems for the bidirectional production of H₂O₂. Full article

Porphyrins play important roles in biological systems including oxygen transport and catalysis. Due to their tetrapyrrole core structure, they exhibit exceptional photophysical and electrochemical properties and find many applications in both technical and life science fields, including photodynamic therapy and neurosurgery. The irradiation of porphyrins may cause modifications to their molecular structure or their degradation. Such photobleaching processes potentially affect the success and sensitivity of photosensitizer applications. While there have been many studies using fluorescence spectroscopy to investigate this phenomenon, reports about analytically validated structures of photoproducts are scarce. It is, however, necessary to know the individual contributions of different molecules to the fluorescence signal in order to evaluate it correctly. This review provides a summary of the current state of knowledge in this respect, discussing especially the validated hydroxyaldehyde and formyl photo-oxidation products of protoporphyrin IX. Full article

In this study, a thin film of silicon carbide (SiC) was deposited on a porous silicon (P-Si) substrate using pulsed laser deposition (PLD). The photo–electrochemical etching method with an Nd: YAG laser at 1064 nm wavelength and 900 mJ pulse energy and at a vacuum of 10⁻² mbar P-Si was utilized to create a sufficiently high amount of surface area for SiC film deposition to achieve efficient SiC film growth on the P-Si substrate. X-ray diffraction (XRD) analysis was performed on the crystalline structure of SiC and showed high-intensity peaks at the (111) and (220) planes, indicating that the substrate–film interaction is substantial. Surface roughness particle topography was examined via atomic force microscopy (AFM), and a mean diameter equal to 72.83 nm was found. Field emission scanning electron microscopy (FESEM) was used to analyze surface morphology, and the pictures show spherical nanoparticles and a mud-sponge-like shape demonstrating significant nanoscale features. Photoluminescence and UV-Vis spectroscopy were utilized to investigate the optical properties, and two emission peaks were observed for the SiC and P-Si substrates, at 590 nm and 780 nm. The SiC/P-Si heterojunction photodetector exhibited rectification behavior in its dark I–V characteristics, indicating high junction quality. The spectral responsivity of the SiC/P-Si observed a peak responsivity of 0.0096 A/W at 365 nm with detectivity of 24.5 A/W Jones, and external quantum efficiency reached 340%. The response time indicates a rise time of 0.48 s and a fall time of 0.26 s. Repeatability was assured by the tight clustering of the data points, indicating the good reproducibility and stability of the SiC/P-Si deposition process. Linearity at low light levels verifies efficient photocarrier generation and separation, whereas a reverse saturation current at high intensities points to the maximum carrier generation capability of the device. Moreover, Raman spectroscopy and energy dispersive spectroscopy (EDS) analysis confirmed the structural quality and elemental composition of the SiC/P-Si film, further attesting to the uniformity and quality of the material produced. This hybrid material’s improved optoelectronic properties, achieved by combining the stability of SiC with the quantum confinement effects of P-Si, make it useful in advanced optoelectronic applications such as UV-Vis photodetectors. Full article

The relentless consumption of fossil fuels and soaring CO₂ emissions have plunged the world into an energy and environmental crisis. As society grapples with these challenges, the demand for clean, renewable, and sustainable energy solutions has never been more urgent. However, even though many efforts have been made in this field, there is still room for improvement concerning efficiency, material stability, and catalytic enhancement regarding kinetics and selectivity of photoelectrochemical (PEC) processes. Herein, we provide the experimental proof for the enhancement of the photocurrent efficiency by the critical focus on semiconductor–electrolyte interface (SEI) properties. By tailoring electrolyte composition, researchers can unlock significant improvements in catalytic efficiency and stability, paving the way for advanced PEC technologies. In this study, we investigate the influence of electrolyte composition on SEI properties and its impact on PEC performance. By employing electrolytes enriched with carbonates, borates, sulphates, and alkali cations, we demonstrate their profound role in optimising photoelectrochemical CO₂ reduction reaction (CO₂RR) efficiency. Central to this work is Cu₂O—an affordable, highly promising photocatalyst. While its potential is undeniable, Cu₂O’s inherent instability and diverse reduction products, ranging from CH₃OH to CO, HCOOH, CH₃COOH, and CH₃CH₂OH, have hindered its widespread adoption in PEC CO₂ reduction (CO₂RR). Our approach leverages a straightforward yet powerful electrodeposition method, enabling a deeper exploration of SEI dynamics during photocatalysis. Key parameters, such as carbonate concentration, local pH, alkali cation presence, anionic geometry, CO₂ solubility, and electrolyte conductivity, are systematically investigated. The findings reveal the formation of a unique “rigid layer” at the photocatalyst surface, driven by specific cation–anion interactions. This rigid layer plays a pivotal role in boosting PEC performance, offering a new perspective on optimising, among other PEC processes, CO₂RR catalytic efficiency. This profound study bridges a critical knowledge gap, shedding light on the dual influence of cations and anions on SEI properties and PEC CO₂RR. By unravelling these intricate interactions, we provide a roadmap for designing next-generation PEC systems. These insights pave the way for sustainable energy advancements, inspiring innovative strategies to tackle one of the most pressing challenges of our time. Full article

Microelectrode-based photoelectrochemical (PEC) technology is a novel and rapidly developing analytical method for the in vivo probing of neurochemical events in the brain, which is distinguished by its low background noise and high detection sensitivity. This mini-review focuses on recent advances in in vivo PEC biosensors. We classify the key characteristics of PEC technology and elucidate its underlying principles. Furthermore, newly developed PEC neurochemical sensing methods for detecting various substances, including SO₂, antibiotics, metal ions, neurotransmitters, and thioalcohols, as well as cells are discussed. Finally, this review concludes with a comprehensive summary and perspectives on the emerging opportunities and challenges facing this field. Full article

A series of Ag-loaded and oxygen vacancy (OV)-containing BiOBr_(OV)/BiOI_0.08 (Ag/BiOBr_(OV)/BiOI_0.08) photocatalysts with varying Ag loading levels were synthesized via the solvothermal–photocatalytic reduction method. As confirmed via optical, photoelectrochemical, and 4-chlorophenol photodegradation experiments, a low Ag loading level significantly enhanced the photogenerated charge carrier (PCC) transfer on the BiOBr_(OV)/BiOI_0.08 semiconductor surface and the performance of Ag/BiOBr_(OV)/BiOI_0.08 photocatalysts, which was attributable to the synergism between the effect of OVs and the localized surface plasmon resonance (LSPR) of Ag nanoparticles. Additionally, BiOBr_(OV)/BiOI heterojunctions facilitated efficient visible-light harvesting and PCC separation. As indicated by finite-difference time-domain (FDTD) simulations and density functional theory (DFT) calculations, the electric field intensity in the “hot spots” generated at the interface between the BiOBr_(OV)/BiOI_0.08 semiconductor and Ag nanoparticles increased by more than eight times, and the presence of OVs and Ag atomic clusters introduced impurity energy levels in the semiconductor bandgap, improving PCC separation and Ag/BiOBr_(OV)/BiOI_0.08 photocatalytic efficiency. However, an increase in silver loading renders the composite metallic, suggesting a reduction in its photocatalytic performance. This work provides new insights for designing highly active visible light catalysts and contributes to the development of more efficient plasmonic catalysts. Full article