Light-to-Hydrogen Improvement Based on Three-Factored Au@CeO₂/Gr Hierarchical Photocatalysts

Recently, various attempts have been made for light-to-fuels conversion, often with limited performance. Herein we report active and lasting three-factored hierarchical photocatalysts consisting of plasmon Au, ceria semiconductor, and graphene conductor for hydrogen production. The Au@CeO₂/Gr_2.0 entity (graphene outer shell thickness of 2.0 nm) under visible-light irradiation exhibits a colossal achievement (8.0 μmol mg_cat^-1 h^-1), which is 2.2- and 14.3-fold higher than those of binary Au@CeO₂ and free-standing CeO₂ species, outperforming the currently available catalysts. Yet, it delivers a high maximum quantum yield efficiency of 38.4% at an incident wavelength of 560 nm. These improvements are unambiguously attributed to three indispensable effects: (1) the plasmon resonant energy is light-excited and transferred to produce hot electrons localizing near the surface of Au@CeO₂, where (2) the high-surface-area Gr conductive shell will capture them to direct hydrogen evolution reactions, and (3) the active graphene hybridized on the defect-rich surface of Au@CeO₂ favorably adsorbs hydrogen atoms, which all bring up thorough insight into the working of a ternary Au@CeO₂/Gr catalyst system in terms of light-to-hydrogen conversion.