Fabrication of WO3 photoanode decorated with Au nanoplates and its enhanced photoelectrochemical properties

Unveiling Morphology-Structure Interplay on Hydrothermal WO3 Nanoplatelets for Photoelectrochemical Solar Water Splitting

Photoelectrochemical (PEC) water splitting offers a sustainable route for hydrogen production, leveraging noncritical semiconductor materials. This study introduces a seed layer-free hydrothermal synthesis approach for semiconductor photoanodes based on tungsten trioxide (WO3) nanoplatelets. Aiming to boost the efficiency of photoelectrochemical water splitting through optimization of the synthesis parameters of bare WO3, focusing on temperature, time, and layer thickness, we systematically explored their effects on the morphological, structural, and optical characteristics of WO3 photoanodes. Combining a low-temperature regime (90 °C for 12 h) with a multilayer strategy (up to six-layers) resulted in significant improvements in photocurrent. Particularly, the five-layer sample exhibited a remarkable increase of over 70% compared to the single-layer photoanode. Morphological aspects, particularly the fractal dimension of nanoplatelets and the emergence of the (220) crystalline orientation, usually neglected, were found to play pivotal roles in modulating the PEC response. Rietveld refinement of X-ray diffraction patterns further underscored the importance of crystallographic facets, volume unit cell expansion, and microstrain in influencing photocurrent outcomes. Furthermore, we adapted the Mott-Schottky equation to incorporate the fractal dimension reflecting the nanostructures' nature, usually set to a planar interface. Our findings highlight the interchange between nanoplatelet morphology and structural parameters in determining the PEC efficiency of WO3 photoanodes.

Fast annealing fabrication of porous CuWO4photoanode for charge transport in photoelectrochemical water oxidation

Ternary-phase CuWO4oxide with an electronic band gap of 2.2-2.4 eV is a potential candidate photoanode material for photoelectrochemical (PEC) water splitting. Herein, we present an efficient method to prepare CuWO4film photoanode by combining hydrothermal method and hybrid microwave annealing (HMA) process. In comparison with conventional thermal annealing (CTA), HMA can achieve CuWO4thin film within minutes by using SiC susceptor. When the CuWO4photoanode is prepared by HMA, its PEC water oxidation performance improves from 0.21 to 0.29 mA cm-2at 1.23 VRHEcomparing with the one prepared by CTA. The origin of the enhanced photocurrent was investigated by means of complementary physical characterizations and PEC methods. The results demonstrated that the obtained HMA processed CuWO4photoanode not only exhibited intrinsic porous nanostructures but also abundant surface hydroxyl groups, which facilitated sufficient mass transport and the charge transfer. Our results highlight the application of HMA for the fast fabrication of porous film photo-electrodes without using sacrificial template.

Ultrasonic-assisted synthesis of magnetic recyclable Fe3O4/rice husk biochar based photocatalysts for ciprofloxacin photodegradation in aqueous solution

In this work, a new facile one-spot method has been designed to fabricate a magnetic recyclable Fe₃O₄/rice husk biochar photocatalyst (FBP) for the removal of Ciprofloxacin (CIP) in aqueous solution. This method combines ultrasonic-assisted impregnation and precipitation, which can overcome the difficulties of long-time reactions, complex procedures, and extreme condition requirements. The successful fabrication of the Fe₃O₄/biochar material has been proven by a series of material characterization techniques, including X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Raman, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and vibrating sample magnetometer (VSM). Moreover, the as-product FBP exhibited the excellent ability of photodegrading CIP and the possibility of magnetic recovery from the aqueous solution, suggesting a potential solution for removing antibiotic pollutants in environmental remediation.

Hydrothermal construction of WO3.0.33H2O/g-C3N4 nanocomposites with enhanced adsorption and photocatalytic activity

Tungsten trioxide has attracted extensive attention for photocatalytic applications owing to its unique structure and intrinsic merits; however, small specific surface area and rapid electron-hole recombination still limit its adsorption...

Metformin-Templated Nanoporous ZnO and Covalent Organic Framework Heterojunction Photoanode for Photoelectrochemical Water Oxidation

Photoelectrochemical water-splitting offers unique opportunity in the utilization of abundant solar light energy and water resources to produce hydrogen (renewable energy) and oxygen (clean environment) in the presence of a semiconductor photoanode. Zinc oxide (ZnO), a wide bandgap semiconductor is found to crystallize predominantly in the hexagonal wurtzite phase. Herein, we first report a new crystalline triclinic phase of ZnO by using N-rich antidiabetic drug metformin as a template via hydrothermal synthesis with self-assembled nanorod-like particle morphology. We have fabricated a heterojunction nanocomposite charge carrier photoanode by coupling this porous ZnO with a covalent organic framework, which displayed highly enhanced photocurrent density of 0.62 mA/cm² at 0.2 V vs. RHE in photoelectrochemical water oxidation and excellent photon-to-current conversion efficiency at near-neutral pH vis-à-vis bulk ZnO. This enhancement of the photocurrent for the porous ZnO/COF nanocomposite material over the corresponding bulk ZnO could be attributed to the visible light energy absorption by COF and subsequent efficient charge-carrier mobility via porous ZnO surface.

The design and growth of peanut-like CuS/BiVO4 composites for photoelectrochemical sensing

In this study, the CuS/BiVO₄-X (where X represents the mass percentage of CuS associated with CuS/BiVO₄; X = 2%, 5% and 7%) p–n heterostructures were fabricated using a two-step hydrothermal method.