In-situ photodeposition of co-catalyst Ni₂P on CdS for photocatalytic conversion of ethanol for synergistic hydrogen production

In this study, Ni₂P/CdS composites were constructed by depositing non-precious metal co-catalyst Ni₂P on a one-dimensional network of CdS using a simple in-situ photodeposition method. The prepared photocatalysts promoted the decomposition of ethanol into high-value-added products while generating hydrogen. The composite photoanodes loaded with the Ni₂P co-catalysts showed significantly higher ethanol conversion and hydrogen production in the visible light region, which was almost three times higher than that of pure CdS. The main products of photocatalytic ethanol production are acetaldehyde (AA) and 2,3-butanediol (2,3-BDA). Compared with CdS, the selectivity of the composite photocatalysts for converting ethanol to acetaldehyde was significantly improved (62% to 78%). Characterization of the prepared photocatalysts confirmed that the loading of Ni₂P co-catalysts on CdS not only broadened the optical region of the catalysts for trapping light but also effectively promoted the separation and transfer of charge carriers, which significantly improved the photocatalytic efficiency of ethanol conversion and hydrogen production in the catalysts. It has been proven through Electron Paramagnetic Resonance testing that loading a Ni₂P co-catalyst on CdS is beneficial for the adsorption of hydroxyethyl radicals (*CH(OH)CH₃), thereby further improving the selectivity of acetaldehyde. This study plays an important role in the rational design of composite catalyst structures and the introduction of co-catalysts to improve catalyst performance, promote green chemistry, advocate a low-carbon society, and promote sustainable development.