Palladium-copper nanodot as novel H2-evolution cocatalyst: Optimizing interfacial hydrogen desorption for highly efficient photocatalytic activity

Noble metal palladium (Pd) is well-known as excellent photocatalytic cocatalyst, but its strong adsorption to hydrogen causes its limited H-2-evolution activity. In this study, the transition metal Cu was successfully introduced into the metallic Pd to weaken its hydrogen-adsorption strength to improve its interfacial Hz-evolution rate via the Pd-Cu alloying effect. Herein, the ultrasmall Pd(100-x)Cu(x )alloy nanodots (2-5 nm) as a novel H-2-evolution cocatalyst were integrated with the TiO2 through a simple NaH2PO2-mediated co-deposition route. The resulting Pd100-xCux/TiO2 sample shows the significantly enhanced photocatalytic H-2-generation performance (269.2 mu mol h(-1)), which is much higher than the bare TiO2. Based on in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) and density functional theory (DFT) results, the as-formed Pd100-xCux alloy nanodots can effectively promote the separation of photo-generated charges and weak the adsorption strength for hydrogen to optimize the process of hydrogen-desorption process on Pd75Cu25 alloy, thus leading to high photocatalytic H-2-evolution activity. Herein, the weakened H adsorption of Pd75Cu25 co-catalyst can be ascribed to the formation of electron-rich Pd after the introduction of weak electro-negativity Cu. The present work about optimizing electronic structure for promoting interfacial reaction activity provides a new sight for the development of the highly efficient photocatalysts. (C) 2022, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

This study successfully introduced transition metal Cu into noble metal palladium to weaken its adsorption strength to hydrogen and improve its activity in photocatalytic H2 evolution. The Pd-Cu alloy nanodots were found to promote the separation of photo-generated charges and optimize the hydrogen desorption process, leading to significantly enhanced photocatalytic H2 generation performance.