Boosting photoelectrochemical water splitting of nanoparticle-assembled CeO2 nanospheres by plasmon-induced hot-electron injection and spatial charge separation

Using solar energy to split water into clean hydrogen through photoelectrochemical (PEC) water splitting of photoanode is the most promising strategy to mitigate the energy crisis in the future. However, it still is a big challenge to simultaneously realize augmentation in the light energy utilization efficiency, surface water oxidation ability, spatial carrier separation of a photoanode during the PEC water splitting process. This study demonstrates for the first time a plasmonic CeO 2 /Au nanoparticle-assembled nanosphere photoanode for PEC water splitting. The experimental tests certify that the fabricated CeO 2 /Au nanosphere photoanode with optimized Au nanoparticles displays drastically boosted PEC water splitting ability. The photocurrent density obtained under bias-free condition and applied bias photon current efficiency of the as-fabricated and optimized CeO 2 /Au nanosphere photoanode are respectively improved by 13.3 and 9 times compared with that of pore CeO 2 nanosphere photoanode. Optical and spectroscopic experiments reveal that Au NPs significantly improve the light energy utilization efficiency and inject energetic hot electrons into CeO 2 . In addition, photoelectrochemical and electrochemical experiments confirm that the sensitization of Au NPs remarkably accelerates surface water oxidation ability and improve the spatial carrier separation efficiency of nanoparticle-assembled CeO 2 nanosphere photoanode. This study demonstrates the potential in the fields of employing plasmonic materials to boost light-driven hydrogen production of photoelectrodes by simultaneously boosting light energy utilization efficiency, surface water oxidation ability and spatial carrier separation efficiency.