Search Results (72)

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

The block layer situated between the active material and electrode in photoelectrochemical devices serves as a critical component for performance enhancement. Using dye-sensitized solar cells as a representative model, this review systematically examines the strategic positioning and material selection criteria of block layers following a concise discussion of their fundamental mechanisms. We categorize block layer architectures into three distinct configurations: single layer, doped layer, and multilayer structures. The electron generation and transport mechanisms to photoelectrodes are analyzed through structural design variations across these configurations. Through representative literature examples, we demonstrate the correlation between material properties and photoconversion efficiency, accompanied by comprehensive performance comparisons. In the single-layer section, we comparatively evaluate the merits and limitations of TiO₂- and ZnO-based block layers. The doped layer discussion traces the evolutionary trajectory from single-dopant systems to co-doping strategies. For multilayer architectures, we elaborate on the flexibility of its functional regulation. Finally, we present a forward-looking perspective on the hot issues that need to be urgently addressed in photoelectrochemical device block layers. Full article

Chlorine plays an essential role in various industries, such as wastewater treatment, disinfection, plastics, and pharmaceuticals, contributing to a significant global demand. Traditional methods of chlorine production, including chemical reactions involving manganese dioxide, potassium chlorate, and potassium permanganate, as well as the electrolysis of saturated salt solutions, are associated with safety and efficiency concerns. This study introduces a novel approach for the photoelectrocatalytic production of chlorine gas through the oxidation of chloride ions in potassium chloride solutions using a dual semiconductor photoelectrode system composed of TiO₂ and Cu₂O. By harnessing solar energy, this system enables the concurrent, safe, and efficient production of both chlorine and hydrogen gases. The TiO₂ photoelectrode is employed for chlorine production, while Cu₂O is used for hydrogen generation. The dual photoelectrode system mimics the process of electrolytic seawater electrolysis, offering a promising alternative to conventional methods. Through linear sweep voltammetry, current–time tests, and electrochemical impedance spectroscopy, we demonstrate the effectiveness of this approach, supported by a detailed analysis of the energy band structure. Additionally, the material’s characteristics were verified using X-ray diffraction (XRD) and scanning electron microscopy (SEM). This work not only provides a safer and more efficient method for chlorine production but also highlights the potential of solar-powered photoelectrocatalysis in large-scale applications. These findings point toward a sustainable and environmentally friendly direction for chlorine production under simulated seawater conditions, with significant implications for renewable energy-driven industrial processes. Full article

This study proposes an alternative process for obtaining ZnO/ZnS:rGO heterostructures for use in DSSCs and as promising materials for potential applications in other photonic process, such as photocatalysis and photodetection. The compound was obtained through a microwave-assisted hydrothermal method, where the electromagnetic waves and temperature were crucial points for forming ZnO, ZnO/ZnS and reducing graphene oxide (GO). The XRD, Raman, FT-IR, and FESEM results presented the structural, morphological, and chemical structures, which suggest the conversion of ZnO to ZnS for samples with higher concentrations of reduced graphene oxide (rGO). Additionally, the optical properties were analyzed through photoluminescence and UV-Vis measurements. The electrical behavior of the photoelectrodes was investigated through J-V measurements in light and dark conditions. In addition, electrochemical impedance spectroscopy (EIS) was performed and Bode phase plots were created, analyzing the recombination processes and electron lifetime. The J-V results showed that for smaller amounts of rGO, the dye-sensitized solar cells (DSSC) efficiency improved compared to the ZnO/ZnS single structure. However, it was observed that with more significant amounts of rGO, the photocurrent value decreased due to the presence of charge-trapping centers. On the other hand, the best results were obtained for the ZnO/ZnS:1% rGO sample, which showed an increase of 14.2% in the DSSC efficiency compared to the pure ZnO/ZnS photoelectrode. Full article

The development of photoelectrochemical tandem cells for water splitting with electrodes entirely based on metal oxides is hindered by the scarcity of stable p-type oxides and the poor stability of oxides in strongly alkaline and, particularly, strongly acidic electrolytes. As a novelty in the context of transition metal oxide photoelectrochemistry, a bias-free tandem cell driven by simulated sunlight and based on a CuCrO₂ photocathode and a WO₃ photoanode, both unprotected and free of co-catalysts, is demonstrated to split water while working with strongly acidic electrolytes. Importantly, the Faradaic efficiency for H₂ evolution for the CuCrO₂ electrode is found to be about 90%, among the highest for oxide photoelectrodes in the absence of co-catalysts. The tandem cell shows no apparent degradation in short-to-medium-term experiments. The prospects of using a practical cell based on this configuration are discussed, with an emphasis on the importance of modifying the materials for enhancing light absorption. Full article

Photoelectrocatalytic approaches show promise for contaminate removal in wastewater through redox reactions. However, the direct treatment of very low concentration heavy metals is a challenging task. Copper bismuth oxide is considered as a potential photocathode material due to its appropriate bandgap width and excellent light absorption properties. In this work, we utilize copper bismuth oxide photoelectrodes with micrometer-scale pores to achieve the efficient and complete reduction of micromolar-level hexavalent chromium(VI) in wastewater. In a continuous 180 min experiment, the reduction rate of 5 µM hexavalent chromium reached 97%, which is an order lower than the drinking standard. Such a process was facilitated by the unique hierarchical microstructure of the oxide thin film and the porous morphology. On the other hand, the structural evolution during the operation was analyzed. A surface passivation was observed, suggesting the possible long-term practical application of this material. This study serves as an important reference for the application of photoelectrocatalysis in addressing Cr(VI) pollution in wastewater, with implications for improving water quality and environmental protection. Full article

Photoelectrochemical cells (PECs) are an important technology for converting solar energy, which has experienced rapid development in recent decades. Transparent conductive oxides (TCOs) are also gaining increasing attention due to their crucial role in PEC reactions. This review comprehensively delves into the significance of TCO materials in PEC devices. Starting from an in-depth analysis of various TCO materials, this review discusses the properties, fabrication techniques, and challenges associated with these TCO materials. Next, we highlight several cost-effective, simple, and environmentally friendly methods, such as element doping, plasma treatment, hot isostatic pressing, and carbon nanotube modification, to enhance the transparency and conductivity of TCO materials. Despite significant progress in the development of TCO materials for PEC applications, we at last point out that the future research should focus on enhancing transparency and conductivity, formulating advanced theories to understand structure–property relationships, and integrating multiple modification strategies to further improve the performance of TCO materials in PEC devices. Full article

Oxynitrides such as LaTa(O,N)₃ are attractive materials as photoelectrodes for photoelectrocatalytic solar water splitting. The potential anionic ordering in their perovskite-type structure has been shown to impact the materials’ properties. Given the importance attributed to it, the present study reports a detailed experimental analysis supported by simulations of the anionic ordering of La_1−xY_xTa(O,N)₃. The influence of O/N and yttrium content on the anionic order was assessed. Neutron diffraction analysis was performed on four different nominal compositions—LaTaON₂, LaTaO₂N, La_0.9Y_0.1TaON₂, and La_0.9Y_0.1TaO₂N—at 10 K and 300 K to study potential long-range ordering. Neutron pair distribution function (PDF) analysis was performed on all samples at 10 K and on non-Y-substituted samples at 300 K to evaluate short-range ordering. There was no evidence of long-range O/N order in any of the compounds. In contrast, at a short range (1.5 Å ≤ r < 6 Å), a Pnma (a⁻b⁺a⁻) tilting pattern and local cis-ordering of the anions were seen. The latter faded rapidly, leaving the Pnma tilting pattern in a 6 Å ≤ r ≤ 11 Å range. At higher distances, the PDF analysis agreed with the Imma (a⁻b⁰a⁻) O/N disordered long-range structure. As the O/N content changed, not much difference in behavior was observed. Yttrium substitution introduced some disorder in the structure; nonetheless, it showed marginal influence on octahedral tilting and anionic ordering. Full article

Photoelectrocatalytic (PEC) water decomposition provides a promising method for converting solar energy into green hydrogen energy. Indeed, significant advances and improvements have been made in various fundamental aspects for cutting-edge applications, such as water splitting and hydrogen production. However, the fairly low PEC efficiency of water decomposition by a semiconductor photoelectrode and photocorrosion seriously restrict the practical application of photoelectrochemistry. In this review, the mechanisms of PEC water decomposition are first introduced to provide a solid understanding of the PEC process and ensure that this review is accessible to a wide range of readers. Afterwards, notable achievements to date are outlined, and unique approaches involving promising semiconductor materials for efficient PEC hydrogen production, including metal oxide, sulfide, and graphite-phase carbon nitride, are described. Finally, four strategies which can effectively improve the hydrogen production rate—morphological control, doping, heterojunction, and surface modification—are discussed. Full article

We synthesized hollow spherical titanium oxide particles, which are one of the structural features of fabricating a thin-film photoelectrode, using the particles and evaluated their properties. The XRD diffraction results confirmed the main phase peaks of the target rutile-type hollow spherical titanium oxide (HSTR) and bronze-type hollow spherical titanium oxide (TiO₂(B)). The calcium carbonate used in the core material was also removed. The photocatalytic reaction measurement result showed that the activity of TiO₂(B) in ultraviolet light of 365 nm was higher than that of TiO₂(B). As shown in the visible spectrum, the photo adsorption wavelength of HSTR was approxim ately 700 nm, whereas TiO₂(B) was generally absorbed around 400 nm. A relationship between an electric current peak and the square root of a scan potential speed suggested a reversible reaction system in light irradiation. Full article

The primary objective of this research is to address the energy challenges by introducing an innovative nanocomposite material. This material is designed to facilitate the conversion of environmentally friendly and economically viable Red Sea water into hydrogen gas. The ultimate goal of this work is to pave the way for the development of a practical device that can be employed within households and industrial settings to directly convert water into hydrogen gas. This novel nanocomposite material synthesized through oxidative polymerization comprises As₂O₃ and Poly-3-methylaniline (P3MA). This material possesses an extensive absorption range, spanning up to 700 nm, and features a bandgap of 1.75 eV, making it a promising candidate for use as a photoelectrode in green hydrogen production. The unique aspect of this setup lies in the utilization of Red Sea water, a natural sacrificing agent, as the electrolyte, rendering the process eco-friendly and cost-effective. When it is employed as a photoelectrode, this material exhibits high sensitivity to green hydrogen production, generating 6 moles/10 cm²·h of hydrogen. At a voltage of −0.83 V, the current density values are measured as −0.08 mA·cm⁻² (J_ph) in light and −0.02 mA·cm⁻² (J_o) in darkness. Furthermore, the photoelectrode’s responsiveness to light is assessed with different optical filters, revealing the optimal performance at 340 nm, where J_ph reaches −0.052 mA·cm⁻². These outcomes provide strong evidence of the photoactivity of the As₂O₃/P3MAphotoelectrode for green hydrogen production using Red Sea water. This underscores its potential for the development of an electrochemical cell for the direct conversion of sea water into H₂ gas. Full article

Solar fuel production using a photoelectrochemical (PEC) cell is considered as an effective solution to address the climate change caused by CO₂ emissions, as well as the ever-growing global demand for energy. Like all other solar energy utilization technologies, the PEC cell requires a light absorber that can efficiently convert photons into charge carriers, which are eventually converted into chemical energy. The light absorber used as a photoelectrode determines the most important factors for PEC technology—efficiency, stability, and the cost of the system. Despite intensive research in the last two decades, there is no ideal material that satisfies all these criteria to the level that makes this technology practical. Thus, further exploration and development of the photoelectode materials are necessary, especially by finding a new promising semiconductor material with a suitable band gap and photoelectronic properties. CuWO₄ (n-type, E_g = 2.3 eV) is one of those emerging materials that has favorable intrinsic properties for photo(electro)catalytic water oxidation, yet it has been receiving less attention than it deserves. Nonetheless, valuable pioneering studies have been reported for this material, proving its potential to become a significant option as a photoanode material for PEC cells. Herein, we review recent progress of CuWO₄-based photoelectrodes; discuss the material’s optoelectronic properties, synthesis methods, and PEC characteristics; and finally provide perspective of its applications as a photoelectrode for PEC solar fuel production. Full article

The synthesis of nanoporous copper oxide (NP-CuO) materials via the dealloying and thermal oxidation of amorphous CuZrAl ribbons, representing the novelty of this research and previously achieved via a melt-spinning process, was carried out in an aqueous hydrofluoric acid (HF) solution by varying the holding time. These nanoporous copper (NPC) structures were used as a template to achieve a 3D-NP-CuO materials with different surface morphologies. To investigate the structural and morphological properties of the obtained sandwich-type materials, X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy (SEM/EDX), and ultraviolet–visible spectroscopy (UV-VIS) techniques were used. In summary, the dealloying and thermal oxidation of amorphous ribbons is an interesting approach to achieving a three-dimensional (3D) network of NP-CuO with different morphologies and with a low production cost. These sandwich-type structures, consisting of NPC and copper oxide nanowires (CuO/Cu₂O), combine the good electrical properties of NPC with the catalytic properties of copper oxide semiconductors, making them suitable materials for photocatalysis, photoelectrodes in solar cells, battery applications, and electrochemical sensors. Full article

The rise in the Earth’s surface temperature on an annual basis has stimulated scientific and engineering interest in developing and implementing alternative energy sources. Besides cost, the main requirements for alternative energy sources are renewability and environmental friendliness. A prominent representative that allows the production of “green” energy is the conversion of solar photons into a practical energy source. Among the existing approaches in solar energy conversion, the process of photoelectrochemical (PEC) hydrogen extraction from water, which mimics natural photosynthesis, is promising. However, direct decomposition of water by sunlight is practically impossible since water is transparent to light waves longer than 190 nm. Therefore, applying a photoelectrochemical process using semiconductor materials and organic compounds is necessary. Semiconductor materials possessing appropriately positioned valence and conduction bands are vital constituents of photoelectrodes. Certain materials exhibit semiconductor characteristics that facilitate the reduction-oxidation (RedOx) reaction of water (H₂O) under specific circumstances. ZnO holds a unique position in the field of photocatalysis due to its outstanding characteristics, including remarkable electron mobility, high thermal conductivity, transparency, and more. This article offers an overview of studies exploring ZnO’s role as a photocatalyst in the generation of hydrogen from water. Full article

The development of a single junction photoelectrode material having specific properties is essential and challenging for the efficient application in solar water splitting for oxygen production and a high value-added product, hydrogen. Moreover, the present material solutions based on binary metal oxides offer limited catalytic activity and hydrogen production efficiency. Therefore, it is paramount to develop and exploit a unique range of materials derived from ternary metal oxides with specifically engineered properties to advance in photoelectrochemical (PEC) water splitting. Among the ternary oxides, copper vanadates offer promising characteristics, such as a narrow bandgap and catalytic surface properties along with favorable band edges for facile oxygen evolution reaction (OER), which is considered the bottleneck step in performing overall water dissociation. Furthermore, the copper vanadates allow the tuning of the stoichiometry through which a wide range of polymorphs and materials could be obtained. This review provides a complete outlook on the range of copper vanadates and the established synthesis approach, morphology, crystal structure, band edge properties, and PEC characterizations. Mainly, the underlying charge dynamic properties, carrier path length, effect of doping, and influence of surface catalysts are discussed. The review concludes that the advancement toward obtaining low-bandgap materials is a main challenge to overcome the limitations for efficient water dissociation to OER and copper vanadates, which offer a promising solution with their unique properties and advantages. Importantly, intense and strategically focused research is vital to overcome the scientific challenges involved in copper vanadates and to explore and exploit new polymorphs to set new efficiency benchmarks and PEC water splitting solutions. Full article