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.

Au-Cu bimetallic thin films with controlled composition were fabricated by magnetron sputtering co-deposition, and their performance for the electrocatalytic reduction of CO2 was investigated. The uniform planar morphology served as a platform to evaluate the electronic effect isolated from morphological effects while minimizing geometric contributions. The catalytic selectivity and activity of Au-Cu alloys was found to be correlated with the variation of electronic structure that was varied with tunable composition. Notably, the d-band center gradually shifted away from the Fermi level with increasing the Au atomic ratio, leading to a weakened binding energy of *CO, which is consistent with low CO coverage observed in CO stripping experiments. The decrease of the *CO binding strength results in the enhanced catalytic activity for CO formation with the increase of Au content. In addition, it was observed that copper oxide/hydroxide species are less stable on Au-Cu surfaces compared to those on pure Cu surface, where the surface oxophilicity could be critical to tuning the binding strength of *OCHO. These results imply that the altered electronic structure could explain the decreased formation of HCOO─ on these alloys. In general, the formation of CO and HCOO─ as main CO2 reduction products on planar Au-Cu alloys followed the shift of d-band center, which indicates the electronic effect is the major governing factor for the electrocatalytic activity of CO2 reduction on Au-Cu bimetallic thin films.

Realization of photo-electrochemical water splitting to generate H₂ alternative fuel requires the facilitation of the kinetically-sluggish oxygen evolution reaction (OER) occurring at the photoanode. To do so, there is a need to develop new methods to assemble suitable OER co-catalysts at the semiconductor–solution interface. Although Metal–Organic Frameworks (MOFs) are frequently used as precursor materials to synthesize high surface area, effective OER electrocatalysts, until now their utilization as co-catalysts in a working photo-electrochemical cell (PEC) has remained underexplored. As a proof-of-concept, here we provide a simple route for modification of BiVO₄-based photoanodes with highly-active porous cobalt-oxide co-catalysts, converted from a cobalt–imidazolium MOF (ZIF-67). Photo-electrochemical and impedance spectroscopy analysis reveal that the co-catalyst significantly accelerates photoanodic OER (rather than serving as a surface passivation layer), and thus greatly improves the overall PEC performance. Hence, given the chemical flexibility of MOFs, this work provides a new tool-kit for designing efficient water splitting PECs.