Bimetallic Synergy in Ultrafine Cocatalyst Alloy Nanoparticles for Efficient Photocatalytic Water Splitting

Abstract

AbstractHerein, PtRu solid‐solution alloy nanoparticles enable high‐performance H2 evolution reaction cocatalysts through the transfer of knowledge from electrocatalysis to photocatalysis. Ultrafine PtRu alloy nanoparticles (1.0 ± 0.2 nm in diameter) are synthesized by using a chemical polyol method and used for electro/photo‐catalyses. Integration of PtRu nanoparticles with carbon and Al‐doped SrTiO3 powders via liquid‐phase adsorption and successive two‐step air and H2 annealing ensures uniform deposition of PtRu alloy nanoparticles (<2 nm) with a solid‐solution structure. The PtRu alloy nanoparticles exhibit higher electrocatalytic activity for the hydrogen evolution reaction than monometallic Pt counterparts. Modifying Al‐doped SrTiO3 with PtRu alloy nanoparticles results in efficient photocatalytic overall water‐splitting activity with an apparent quantum yield of 65% at 365 nm and a solar‐to‐hydrogen energy conversion efficiency of 0.45%, which are the highest values among SrTiO3‐based photocatalytic water splitting systems with Rh‐free cocatalysts. Transient diffuse reflectance spectroscopy reveals that the PtRu nanoparticles have a superior electron‐capturing ability than the Pt counterparts, probably due to the decreased work function of Pt by alloying with Ru. This work establishes a framework to elucidate catalytic trends and provides rational design guidance toward the development of bimetallic solid‐solution nanoparticles as cost‐effective and highly active cocatalysts for overall water splitting.