Search Results (137)

This study investigates the synthesis and characterization of boron-modified nanotubular titania (NTO) arrays fabricated via a single-step anodizing process with varying concentrations of boric acid (BA). Following anodization, a reductive heat treatment was applied to facilitate the crystallization of the anatase phase in the boron-modified NTO. The effect of the BA concentration on the structural, morphological, and photoelectrochemical (PEC) properties of the NTOs was systematically explored through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), luminescence, and UV-Vis spectrometry. The introduction of boron during anodization facilitated the formation of sub-bandgap states, thereby enhancing the light absorption and electron mobility. This study revealed the optimal BA concentration that yielded a 3.3-fold enhancement of the PEC performance, attributed to a reduction in the bandgap energy. Notably, the highest incident photon-to-current conversion efficiency (IPCE) was observed for NTO samples anodized at a 0.10 M BA concentration. These findings underscore the promise of boron-modified NTOs for advanced photocatalytic applications, particularly in solar-driven water-splitting processes. Full article

A hierarchical photoanode composed of amorphous indium phosphate (InPO_x)-coated titanium dioxide nanowires (TiO₂ NWs) was successfully fabricated via a hydrothermal method followed by dip-coating and thermal phosphidation. Structural characterization revealed the formation of a uniform InPO_x shell on the surface of vertically aligned TiO₂ NWs, without altering their 1D morphology. X-ray photoelectron spectroscopy confirmed the incorporation of phosphate species and the presence of oxygen vacancies, which contribute to enhanced interfacial charge dynamics. Photoelectrochemical (PEC) measurements demonstrated that the InPO_x/TiO₂ NWs significantly improved photocurrent density, with the 0.1 M InCl₃-derived sample achieving 0.36 mA·cm⁻² at 1.0 V—an enhancement of approximately 928% over pristine TiO₂. This enhancement is attributed to improved charge separation and injection efficiency (91%), as well as reduced interfacial resistance verified by electrochemical impedance spectroscopy. Moreover, the Mott–Schottky analysis indicated a four-order increase in carrier density due to the InPO_x shell. The modified electrode also exhibited superior stability under continuous illumination for 3 h. These findings highlight the potential of amorphous InPO_x as an effective cocatalyst for constructing efficient and durable TiO₂-based photoanodes for solar-driven water-splitting applications. Full article

In recent years, researchers have made great efforts to develop effective semiconductor photocatalysts to harness the visible spectrum of sunlight in photocatalytic applications. Bismuth vanadate, BiVO₄, has emerged as one of the most promising candidates for photocatalytic applications among the few non-titania-based visible-light-driven semiconductor photocatalysts. BiVO₄-based structures are intensively studied due to their exceptional ionic conductivity, photocatalytic behavior under ultra-violet and visible light, dielectric properties, ferroelastic and paraelastic phase transitions, and strong pigmentation. BiVO₄ occurs in nature in three crystalline structures: orthorhombic pucherite, tetragonal dreyerite (tz), and monoclinic clinobisvanite (ms). All three crystal structures of BiVO₄ are n-type semiconductors with corresponding energy gap values of 2.34, 2.40, and 2.90 eV, respectively. Different methods of synthesis have been reported for the preparation of BiVO₄ structures of varying morphologies and sizes. The morphology of BiVO₄ is strongly influenced by the preparation method and reaction parameters. A comprehensive systematic study of developments, preparation methods, structure, properties, and advances in different applications over the past decades in research on BiVO₄-based structures will be described. Finally, the current challenges and future outlook of BiVO₄-based structures will be highlighted, in the hope of contributing to guidelines for future applications. Full article

Despite significant progress in photoelectrochemical (PEC) water splitting, high fabrication costs and limited efficiency of photoanodes hinder practical applications. Bismuth vanadate (BiVO₄), with its low cost, non-toxicity, and suitable band structure, is a promising photoanode material but suffers from poor charge transport, sluggish surface kinetics, and photocorrosion. In this study, porous monoclinic BiVO₄ films are fabricated via a simplified successive ionic layer adsorption and reaction (SILAR) method, followed by borate treatment and PEC deposition of NiFeO_x. The resulting B/BiVO₄/NiFeO_x photoanode exhibits a significantly enhanced photocurrent density of 2.45 mA cm⁻² at 1.23 V vs. RHE—5.3 times higher than pristine BiVO₄. It also achieves an ABPE of 0.77% and a charge transfer efficiency of 79.5%. These results demonstrate that dual surface modification via borate and NiFeO_x is a cost-effective strategy to improve BiVO₄-based PEC water splitting performance. This work provides a promising pathway for the scalable development of efficient and economically viable photoanodes for solar hydrogen production. Full article

The rational design of photoanode materials is pivotal for advancing photoelectrochemical (PEC) water splitting toward sustainable hydrogen production. This review highlights recent progress in the machine learning (ML)-assisted development of nanostructured metal oxide photoanodes, focusing on bridging materials discovery and device-level performance optimization. We first delineate the fundamental physicochemical criteria for efficient photoanodes, including suitable band alignment, visible-light absorption, charge carrier mobility, and electrochemical stability. Conventional strategies such as nanostructuring, elemental doping, and surface/interface engineering are critically evaluated. We then discuss the integration of ML techniques—ranging from high-throughput density functional theory (DFT)-based screening to experimental data-driven modeling—for accelerating the identification of promising oxides (e.g., BiVO₄, Fe₂O₃, WO₃) and optimizing key parameters such as dopant selection, morphology, and catalyst interfaces. Particular attention is given to surrogate modeling, Bayesian optimization, convolutional neural networks, and explainable AI approaches that enable closed-loop synthesis-experiment-ML frameworks. ML-assisted performance prediction and tandem device design are also addressed. Finally, current challenges in data standardization, model generalizability, and experimental validation are outlined, and future perspectives are proposed for integrating ML with automated platforms and physics-informed modeling to facilitate scalable PEC material development for clean energy applications. Full article

This review presents a comprehensive overview of recent advances in TiO₂-based photoelectrocatalysis (PEC), with an emphasis on material design strategies to enhance visible-light responsiveness and charge carrier dynamics. Key approaches—including elemental doping, defect engineering, heterojunction construction, and plasmonic enhancement—are systematically discussed in relation to their roles in modulating energy band structures and promoting charge separation. Beyond fundamental mechanisms, the review highlights the broad environmental and energy-related applications of TiO₂-driven PEC systems, encompassing the degradation of persistent organic pollutants, microbial disinfection, heavy metal removal, photoelectrochemical water splitting for hydrogen production, and CO₂ reduction. Recent progress in integrating PEC systems with energy harvesting modules to construct self-powered platforms is critically examined. Current limitations and future directions are also outlined to guide the rational development of next-generation TiO₂-based photoelectrocatalytic systems for sustainable environmental remediation and solar fuel conversion. Full article

Hematite (Fe₂O₃) has been accepted as a promising and potential photo(electro)catalyst. However, its poor carrier separation and transfer efficiency has limited its application for photoelectrocatalytic (PEC) water oxidation. Herein, a S-doped FeOOH (S:FeOOH) layer was rationally designed and grown on Fe₂O₃ to construct a S:FeOOH/Fe₂O₃ composite photoanode. The obtained S:FeOOH/Fe₂O₃ photoanodes were fully characterized. The surface injection efficiency for Fe₂O₃ was then significantly increased with a high η_surface value of 92.8%, which increases to 2.98 times for Fe₂O₃ and 2.16 times for FeOOH/Fe₂O₃, respectively. With 2.43 mA cm^‒2 at 1.23 V, the optimized S:FeOOH/Fe₂O₃ photoanode was entrusted with a higher photocurrent density. The onset potential for S:FeOOH/Fe₂O₃ cathodically shifts 70 mV over Fe₂O₃. The improved PEC performance suggests that the S:FeOOH layer acts as ultrafast transport channels for holes at the photoanode/electrolyte interface, suppressing surface charge recombination. A Z-scheme band alignment between Fe₂O₃ and S:FeOOH was deduced from the UV–Vis and UPS spectra to promote charge transfer. This method provides an alternative for the construction of photoanodes with enhanced PEC water splitting performance. Full article

NiFe₂O₄ and TiO₂ are widely studied for photoelectrochemical (PEC) applications due to their unique properties. Nitrogen-doped graphene (NG) and metal–organic frameworks (MOFs), such as MIL-100(Fe) (where MIL stands for Materials of Lavoisier Institute), are commonly incorporated to enhance PEC performance by offering a high surface area and facilitating efficient charge transport. Composite systems are commonly employed to overcome the limitations of individual PEC catalysts. In this study, a highly efficient NiFe₂O₄/NG@MIL-100(Fe)/TiO₂ photoanode was developed to enhance photoelectrochemical water-splitting performance. The composite was synthesized via a hydrothermal method with a two-step heating process. X-ray diffraction confirmed the expected crystal structures, with peak broadening in NiFe₂O₄ indicating reduced crystallite size and increased lattice strain. X-ray photoelectron spectroscopy of the Ni 2p and Fe 2p regions validated the successful integration of NiFe₂O₄ into the composite. Electrochemical analysis demonstrated excellent performance, with linear sweep voltammetry achieving a peak photocurrent density of 3.5 mA cm⁻² at 1.23 V (vs RHE). Electrochemical impedance spectroscopy revealed a reduced charge-transfer resistance of 50 Ω, indicating improved charge transport. Optical and electronic properties were evaluated using UV-Vis spectroscopy and Tauc plots, revealing a direct bandgap of 2.1 eV. The composite exhibited stable photocurrent under amperometric J-t testing for 2000 s, demonstrating its durability. These findings underscore the potential of NiFe₂O₄/NG@MIL-100(Fe)/TiO₂ as a promising material for renewable energy applications, particularly in photoelectrochemical water splitting. Full article

This study focuses on enhancing the photoelectrocatalytic (PEC) performance of LaFeO₃ photocathodes by incorporating Ag nanocrystals. LaFeO₃, a perovskite-type metal oxide semiconductor, has potential in PEC water splitting but suffers from fast charge carrier recombination. Ag nanoparticles are introduced due to their surface plasmon resonance (SPR) property and ability to form Schottky junctions with LaFeO₃. A series of Ag/LaFeO₃ materials are prepared using the molten salt method for LaFeO₃ synthesis and the direct reduction method for Ag loading. The results show that Ag nanoparticles are uniformly dispersed on LaFeO₃. The 3 mol% Ag/LaFeO₃ photocathode demonstrates a remarkable ninefold increase in photocurrent density (15 mA·cm⁻² at −0.2 V vs. RHE) compared to pure LaFeO₃ (1.7 mA·cm⁻²). The band gap of LaFeO₃ is reduced from 2.07 eV to 1.92 eV with 3 mol% Ag loading, and the charge transfer impedance is reduced by 77%, while the carrier concentration increases by 2.3 times. The novelty of this work lies in the comprehensive investigation of the interaction mechanisms between Ag nanoparticles and LaFeO₃, which lead to enhanced light absorption, improved charge separation, and increased electrochemical activity. The optimized Ag loading not only improves the photocatalytic efficiency but also enhances the stability of the photocathode. This work provides valuable insights into the interaction between Ag and LaFeO₃, and offers experimental and theoretical support for developing efficient photocatalytic materials for PEC water splitting. 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

In sustainable hydrogen generation, photoelectrochemical (PEC) water splitting stands as a crucial technology, offering solutions to the global energy crisis while tackling environmental challenges. PEC water splitting relies on metal oxide nanostructures due to their unique electronic and optical characteristics. This research highlights the development of a CuO-Fe₂O₃@g-C₃N₄ nanocomposite, created through the integration of three components and fabricated via a one-pot hydrothermal process, precisely engineered to enhance PEC water-splitting efficiency. The combination of CuO, Fe₂O₃, and g-C₃N₄ results in a unified heterojunction structure that efficiently mitigates issues associated with charge carrier recombination and structural stability. Additionally, the analyses of both the structure and composition confirmed the precise synthesis of the composite. The CuO-Fe₂O₃@g-C₃N₄ nanocomposite achieved a photocurrent density of 1.33 mA cm⁻² vs. Ag/AgCl upon exposure to light, demonstrating superior PEC performance and outperforming the individual CuO and Fe₂O₃ components. The enhanced performance is attributed to g-C₃N₄ acting as a photoactive material, generating charge carriers, while the combination of CuO-Fe₂O₃ enables efficient carrier separation and mobility. This synergistic interaction significantly enhances photocurrent generation and ensures long-term stability, positioning the material as a highly promising solution for sustainable hydrogen production. These results highlight the promise of hybrid nanocomposites in driving progress in renewable energy technologies, opening new avenues for the development of more efficient and long-lasting PEC systems. Full article

Hydrogen production via water splitting is a crucial strategy for addressing the global energy crisis and promoting sustainable energy solutions. This review systematically examines water-splitting mechanisms, with a focus on photocatalytic and electrochemical methods. It provides in-depth discussions on charge transfer, reaction kinetics, and key processes such as the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Various electrode synthesis techniques, including hydrothermal methods, chemical vapor deposition (CVD), pulsed laser deposition (PLD), and radio frequency sputtering (RF), are reviewed for their advantages and limitations. The role of carbon-based materials such as graphene, biochar, and graphitic carbon nitride (g-C₃N₄) in photocatalytic and photoelectrochemical (PEC) water splitting is also highlighted. Their exceptional conductivity, tunable band structures, and surface functionalities contribute to efficient charge separation and enhanced light absorption. Further, advancements in heterojunctions, doped systems, and hybrid composites are explored for their ability to improve photocatalytic and PEC performance by minimizing charge recombination, optimizing electronic structures, and increasing active sites for hydrogen and oxygen evolution reactions. Key challenges, including material stability, cost, scalability, and solar spectrum utilization, are critically analyzed, along with emerging strategies such as novel synthesis approaches and sustainable material development. By integrating water splitting mechanisms, electrode synthesis techniques, and advancements in carbon-based materials, this review provides a comprehensive perspective on sustainable hydrogen production, bridging previously isolated research domains. Full article

Fibrous SiO₂-TiO₂ (FST) is one of the most promising materials for advancing photoelectrochemical water-splitting technology due to its cost-effectiveness and environmental friendliness. However, FST faces intrinsic limitations, including its low conductivity and wide bandgap. In this study, significant progress was made in modifying FST to overcome some of these limitations. This work involved synthesizing a new photoanode made of Ag-doped FST utilizing the microemulsion process. The Ag-doped FST was characterized using XRD, FTIR, UV–Vis, DRS, N₂ adsorption–desorption, FESEM, TEM, and XPS. The results confirmed the formation of a continuous concentric lamellar structure with a large surface area. The addition of Ag species into the FST matrix caused interactions that reduced the bandgap. The Ag-doped FST photoanode exhibited an impressive photocurrent density of 13.98 mA/cm² at 1.2 V (vs. RHE). This photocurrent density was notably higher than that of FST photoanodes, which was 11.65 mA/cm² at 1.2 V (vs. RHE). Furthermore, the conduction band of Ag-doped FST is positioned closer to the reduction potential of hydrogen compared to that of FST, SiO₂, and TiO₂, facilitating rapid charge transfer and enabling the spontaneous generation of H₂. The fabrication of Ag-doped FST provides valuable insights into the development of high-performance photoanodes for PEC water splitting. Full article

The modular photoelectrochemical (PEC) reactor accommodating eight photoelectrodes with a total active area of up to 46 cm² has been designed and manufactured using the fused deposition modeling method. The device was equipped with an electrolyte flow system, a relay module for the photoelectrode connection, and a feedback-loop module for switching between counter electrodes. The performance and durability of the system were tested within three case study experiments. The water splitting process was successfully combined with an in situ hydrogen storage in the form of metal hydride phases (confirmed by powder X-ray diffraction) using Fe₂O₃- or WO₃-based photoanodes and LaNi₅-based cathodes. The PEC water oxidation at the anodes was realized either in a strongly alkaline electrolyte (pH > 13.5) or in acidified synthetic seawater (pH < 2) for Fe₂O₃ and WO₃ electrodes, respectively. In the latter case, the photoresponse of the anodes decreased the cell charging voltage by 1.7 V at the current density of 60 mA∙g⁻¹. When the seawater was used as an anolyte, the oxygen evolution reaction was accompanied by the chlorine evolution reaction. The manufactured PEC-metal hydride reactor revealed mechanical and chemical stability during a prolonged operation over 300 h and in the broad range of pH values. Full article

In the realm of photoelectrocatalytic (PEC) water splitting, the BiVO₄/WO₃ photoanode exhibits high electron–hole pair separation and transport capacity, rendering it a promising avenue for development. However, the charge transport and reaction kinetics at the heterojunction interface are suboptimal. This study uses the hydrothermal–electrodeposition–dip coating–calcination method to prepare a microcrystalline WO₃ photoanode thin film as the substrate material and combines it with nanocrystalline BiVO₄ to form a micro–nano-structured heterojunction photoanode to enhance the intrinsic and surface/interface charge transport properties of the photoanode. Under the condition of 1.23 V vs. RHE, the photoelectric current density reaches 1.09 mA cm⁻², which is twice that of WO₃. Furthermore, by using a simple impregnation–mineralization method to load the amorphous FeOOH catalyst, a noncrystalline–crystalline composite structure is formed to increase the number of active sites on the surface and reduce the overpotential of water oxidation, lowering the onset potential from 0.8 V to 0.6 V (vs. RHE). The photoelectric current density is further increased to 2.04 mA cm⁻² (at 1.23 V vs. RHE). The micro–nano-structure and noncrystalline–crystalline composite structure proposed in this study will provide valuable insights for the design and synthesis of high-efficiency photoelectrocatalysts. Full article