The oxygen evolution reaction is the bottleneck to energy-efficient water-based electrolysis for the production of hydrogen and other solar fuels. In proton exchange membrane water electrolysis (PEMWE), precious metals have generally been necessary for the stable catalysis of this reaction. In this work, we report that delamination of cobalt tungstate enables high activity and durability through the stabilization of oxide and water-hydroxide networks of the lattice defects in acid. The resulting catalysts achieve lower overpotentials, a current density of 1.8 amperes per square centimeter at 2 volts, and stable operation up to 1 ampere per square centimeter in a PEMWE system at industrial conditions (80°C) at 1.77 volts; a threefold improvement in activity; and stable operation at 1 ampere per square centimeter over the course of 600 hours.

Inspired by the outstanding optoelectronic properties reported for all-inorganic halide perovskite quantum dots (QDs), we have evaluated the potential of these materials towards the photocatalytic and photoelectrochemical degradation of organic compounds, taking the oxidation of 2-mercaptobenzothiazole (MBT) as a proof-of-concept. First, we determined electrochemically the energy levels of dispersions of perovskite QDs with different bandgap induced by the different ratios between halides (Br and I) and metallic cations (Pb and Sn). Then, we select CsPbBr₃ QDs to demonstrate the photocatalytic and photoelectrochemical oxidation of MBT, confirming that hole injection takes place from CsPbBr₃ QDs to MBT, resulting in the total degradation of MBT as evidenced by Electro Spray Mass Spectrometry analyses. Although the stability and toxicity of these QDs are major issues to address in the near future, the results obtained in the present study open promising perspectives for the implementation of solar-driven catalytic strategies based on these fascinating materials.

The efficient integration of photoactive and catalytic materials is key to promoting photoelectrochemical water splitting as a sustainable energy technology built on solar power. Here, we report highly stable water splitting photoanodes from BiVO₄ photoactive cores decorated with CoFe Prussian blue-type electrocatalysts (CoFe-PB). This combination decreases the onset potential of BiVO₄ by ∼0.8 V (down to 0.3 V vs reversible hydrogen electrode (RHE)) and increases the photovoltage by 0.45 V. The presence of the catalyst also leads to a remarkable 6-fold enhancement of the photocurrent at 1.23 V versus RHE, while keeping the light-harvesting ability of BiVO₄. Structural and mechanistic studies indicate that CoFe-PB effectively acts as a true catalyst on BiVO₄. This mechanism, stemming from the adequate alignment of the energy levels, as showed by density functional theory calculations, allows CoFe-PB to outperform all previous catalyst/BiVO₄ junctions and, in addition, leads to noteworthy long-term stability. A bare 10–15% decrease in photocurrent was observed after more than 50 h of operation under light irradiation.

CO2 electroreduction is a promising technology to produce chemicals and fuels with renewable energy. Polycrystalline and nanostructured metals have been tested extensively while less effort has been spent on understanding the performance of bimetallic alloys. In this communication, we study compositely variant, smooth Au-Pd thin film alloys to discard any morphological or mesoscopic effect on the electrocatalytic performance. We find that the onset potential of CO formation exhibits a strong dependence on the Pd content of the alloys. Strikingly, palladium, a hydrogen evolution catalyst with reasonable exchange current density, supresses hydrogen evolution when alloyed with gold at the presence of CO2. Voltammetric studies suggest that by alloying Au with Pd, a significant increase in the surface coverage of CO2 reduction intermediates occur with increasing Pd content. Such an increase in CO2 reduction intermediate coverage supresses H2 evolution and increases the selectivity towards CO at low overpotentials, where the polycrystalline Au suffers from poor selectivity for CO production. These results suggest that promising CO2 reduction electrode materials (e.g., Au) can be alloyed, not only to tune the catalyst’s activity, but also to deliberately decrease the availability of surface sites for H2 evolution.