Insight into interface charge regulation through the change of the electrolyte temperature toward enhancing photoelectrochemical water oxidation

Fabrication of a Novel Co/CoO@Fe2 V4 O13 Composite Catalyst as a Photoanode for Enhanced Photoelectrochemical Water Oxidation

Herein, the synthesis of a novel composite photocatalyst, Co/CoO@Fe2 V4 O13 , is reported by the deposition of CoO metal oxide nanoparticles on the surface of Fe2 V4 O13 bimetallic oxide. The synthesised photocatalyst exhibited a band gap of roughly 1.8 eV, rendering it responsive to the complete visible light spectrum of the sun, thereby enabling optimal absorption of solar radiation. The Co/CoO@Fe2 V4 O13 composites demonstrated an enhanced photoelectrochemical water oxidation capacity compared to pristine Fe2 V4 O13 when exposed to visible light. The enhanced performance is attributed primarily to the creation of a p-n junction at the interface of Fe2 V4 O13 and Co/CoO, as well as the Z-scheme charge transfer mechanism, which aids in the separation and transfer of photogenerated charge carriers. Light absorption by Co nanoparticles via plasmonic excitation and intra- and inter-band transitions in the composite structure is also likely, resulting in increased composite efficiency. Our findings indicate that Co/CoO@Fe2 V4 O13 composites show promising performance for solar water splitting applications and offer new perspectives for designing effective photocatalysts.

Thermal Effect on Photoelectrochemical Water Splitting Toward Highly Solar to Hydrogen Efficiency

Photoelectrochemical (PEC) hydrogen production is an emerging technology that uses renewable solar light aimed to establish a sustainable carbon-neutral society. The barriers to commercialization are low efficiency and high cost. To date, researchers have focused on materials and systems. However, recent studies have been conducted to utilize thermal effects in PEC hydrogen production. This Review provides a fresh perspective to utilize the thermal effects for PEC performance enhancement while delineating the underlying principles and equations associated with efficiency. The fundamentals of the thermal effect on the PEC system are summarized from various perspectives: kinetics, thermodynamics, and empirical equations. Based on this, materials are classified as plasmonic metals, quantum dot-based semiconductors, and photothermal organic materials, which have an inherent response to photothermal irradiation. Finally, the economic viability and challenges of these strategies for PEC are explained, which can pave the way for the future progress in the field.

Dual modification of BiVO4 photoanode for synergistically boosting photoelectrochemical water splitting

Bismuth vanadate (BiVO₄) is a promising nanomaterial for photoelectrochemical (PEC) water oxidation. However, the serious charge recombination and sluggish water oxidation kinetics limit its performance. Herein, an integrated photoanode was successfully constructed by modifying BiVO₄ (BV) with In₂O₃ (In) layer and further decorating amorphous FeNi hydroxides (FeNi). The BV/In/FeNi photoanode exhibited a remarkable photocurrent density of 4.0 mA cm^-2 at 1.23 V_RHE, which is approximately 3.6 times larger than that of pure BV. And the water oxidation reaction kinetics has an over 200% increased. This improvement was mainly because the formation of BV/In heterojunction inhibited charge recombination, and the decoration of cocatalyst FeNi facilitated the water oxidation reaction kinetics and accelerated hole transfer to electrolyte. Our work provides another possible route to develop high-efficiency photoanodes for practical applications in solar conversion.

Construction of Sb2S3/CdS/CdIn2S4 cascaded S-scheme heterojunction for improving photoelectrochemical performance

Antimony sulfide (Sb₂S₃) is a relatively abundant and environmentally friendly emerging photovoltaic material, which has been gradually applied in solar cells and photocatalysis. It has high light absorption capacity, but it suffers many deep-level defects and is prone to recombination of electron-hole pairs within itself. Here, by constructing the Sb₂S₃/CdIn₂S₄ S-scheme heterojunction, we avoided the problem that electrons and holes cannot be separated and transported effectively due to many Sb₂S₃ defects (more recombination centers), and improved its application in the field of photoelectrochemical water splitting. Meanwhile, in order to further improve the performance of Sb₂S₃/CdIn₂S₄ photoelectrode, we introduced CdS energy platform between Sb₂S₃ and CdIn₂S₄ to form a Sb₂S₃/CdS/CdIn₂S₄ cascaded S-scheme heterojunction. Compared with Sb₂S₃ monomer, Sb₂S₃/CdS/CdIn₂S₄ had higher absorbance intensity, IPCE value, ABPE value, and lower charge transfer resistance. In addition, the photocurrent density of the Sb₂S₃/CdS/CdIn₂S₄ photoelectrode was about 4.20 mA/cm² (1.23 V vs. RHE), which was 1.3 times higher than that of the Sb₂S₃/CdIn₂S₄ photoelectrode (3.29 mA/cm²) and 3.2 times higher than that of monomer Sb₂S₃ photoelectrode (1.32 mA/cm²). This method offers new prospects for optimizing the performance of antimony chalcogenides photoelectrodes for photoelectrochemical water splitting.

Spinel-Oxide-Integrated BiVO4 Photoanodes with Photothermal Effect for Efficient Solar Water Oxidation

Spinel oxide materials have been widely used as oxygen evolution catalysts to enhance the photoelectrochemical (PEC) performance of photoelectrodes. Herein, we demonstrate that the water splitting efficiency of a photoanode can be further enhanced by introducing its photothermal effect. Under near-infrared radiation, the temperature of the NiCo₂O₄/BiVO₄ photoanode increases moderately, leading to improved water oxidation kinetics and charge transport simultaneously. With the assistance of the photothermal effect, the obtained photoanode reaches a photocurrent density of 6.20 mA cm^-2 at 1.23 V vs reversible hydrogen electrode. A series of spinel-type MCo₂O₄ oxides (M = Mn, Zn, Cu, and Fe) are deposited on the surface of the BiVO₄ photoanode to show similar photothermally enhanced PEC performance. The research discovery provides a way for improving the catalytic activity of photoanode materials with a photothermal effect, which may be applied to various fields of energy conversion, including CO₂ reduction, N₂ fixation, and pollutant degradation.