Plasmonic Au–Ru–CeO2 Aerogel Photocatalysts for Nonoxidative Methane Coupling Reaction

In this paper, a series of Au–Ru–CeO2 aerogel-based photocatalysts are constructed for the nonoxidative methane coupling reaction. A modified epoxide-adding method is employed to incorporate Au and Au–Ru nanoparticles into the CeO2 aerogel framework. While the pristine CeO2 shows negligible activity, it is found that the incorporation of Au nanoparticles can greatly enhance the photoactivity, which is attributed to the improved charge separation efficiency and the surface plasmon resonance effect of Au. The nonoxidative methane coupling reaction then becomes feasible in the visible light region. The C2H6 yield rate on Au–CeO2 aerogel photocatalyst can reach 3.17 μmol/g/h under full-spectrum light and 0.48 μmol/g/h under visible light. Adding an appropriate amount of Ru to the above composite during the synthesis can further improve the activity. By screening several Au–Ru–CeO2 aerogel photocatalysts, an optimized Au-to-Ru ratio (10:1) is found. The C2H6 yield rate on Au10Ru1–CeO2 aerogel photocatalyst can be further increased to 7.09 and 1.55 μmol/g/h, under the full-spectrum light and visible light, respectively. Theoretical calculation shows that a small amount of Ru can lower the reaction barrier of H2 evolution and facilitate the overall reaction.