Tailoring the Au size and loading of plasmonic Au/CeO2−x catalysts for the light-powered reverse water gas shift reaction

Abstract

In this study, plasmonic Au/CeO2-x catalysts were synthesized, characterized, and tested for the light-driven reverse water gas shift (rWGS) reaction. Phase-pure CeO2-x was successfully prepared via both static and rotary hydrothermal synthesis, yielding comparable particle sizes and crystallinity. Gold nanoparticles (< 7 nm) were deposited via an Sn2+-assisted seeded growth method, which ensured a uniform distribution of gold on the surface. By systematically varying the Au and Sn precursor contents, the gold loading could be effectively tailored, while the gold particle size remained largely constant. Catalytic tests demonstrated that CO production increases significantly under simultaneous heating and illumination. However, catalytic activity remained lower than that of reference catalysts based on Au/CeO2-x and Au/TiO2, possibly due to excessive Sn coverage shielding active sites (Ce3+ and oxygen vacancies) on the surface. One catalyst (S7-S) showed a color change and spectral shifts after reaction, indicating potential instability. These findings emphasize the importance of a balanced Sn concentration for both performance and structural stability of Au/CeO2-x catalysts.