Cu and Pd dual-single-atoms anchored titanium dioxide for remarkable photocatalytic H2 evolution efficiency

Metal single-atoms (SA) are considered as an effective cocatalyst in photocatalyst for their unsaturated coordination and distinguished activity. However, the precious metal single-atoms catalyst (SACs) approach the maximum activity limit, how to further improve the catalytic efficiency is challenging. In this work, an atomic-level photocatalyst was designed to use the synergy between Pd and Cu dual-SA constructed on TiO2 surface. The synthesized PdCu/TiO2 photocatalyst achieves ultrahigh and stable photocatalytic activity with H2 production of 94.35 mmol∙g−1∙h−1 by splitting water, which is 2.65 and 2.78 times to the PdSA/TiO2 and CuSA/TiO2, respectively, which also higher than most reported photocatalysts. Furthermore, the apparent quantum efficiency (AQE) reaches 83.81 % at 365 nm. Detailed investigations indicate that the outstanding activity of PdCu/TiO2 is mainly attributed to the Pd-O-Cu dimer-site formed in the photocatalyst, which can not only effectively facilitate the photoelectrons transfer to the active site and inhibit the recombination, but also balance the H* adsorption–desorption during the photocatalytic H2 evolution (PHE) process, thus greatly promoting the splitting water reaction. This work provides a new insight for developing bimetallic SACs with high PHE efficiency.