v: The Role of Ion Migration and Alloy Formation on the Stability of Core Shell Cocatalysts for Photoinduced Water Splitting

Semiconductor−metal nanoparticle composites can mediate the photoinduced reaction of water to H2 and O2. High spatial resolution microscopic analysis was used to investigate the structure and composition of nominally NiO/Ni core shell nanoparticles supported on the semiconductors NiTa2O6 and InTaO4, respectively. For NiTa2O6 the metal nanoparticles were confirmed as NiO/Ni core shell structures and photoreaction demonstrated that H2 and O2 were evolved from water at 2.75 and 1.00 μmol g−1 h−1, respectively, under ca. 1 W/cm−2 using an unfiltered 300W Xe lamp. Analysis of the composite after reaction showed evidence of degradation of the NiO/Ni nanoparticles to Ni(OH)2. For InTaO4 bulk modification of the core shell nanoparticles occurred via diffusion of indium ions from the InTaO4 semiconductor to the nanoparticles to give a new core shell structure best formulated as Ni1.25In0.75O3/Ni3In. Although all other analytical data (PXRD, DRUVS, BET, SEM) is essentially identical to that reported for NiO/Ni:InTa...