High-Density Ultrafine Au Nanocluster-Doped Co-LDH Nanocages for Enhanced Visible-Light-Driven CO2 Reduction

Developing effective photocatalysts for CO2 reduction to high value-added chemicals or fuels is a promising strategy for alleviating serious environmental problems and energy crisis. Currently, the photocatalytic efficiency is still too slow to arouse industrial interest for most semiconductor photocatalysts due to their low CO2 uptake, limited visible light capture capacity, and serious recombination of electron-hole. Herein, we successfully synthesized a high-density ultrafine Au cluster (similar to 0.7 nm)-doped cobalt-layered double hydroxide nanocage (Au/Co-LDH) photocatalyst through an in situ redox strategy to explore the structure-activity relationship in the CO2 reduction system. A series of experimental characterizations showed that CO2 adsorption, visible light capture capacity, and charge transfer rate are significantly enhanced due to the highly dispersed and ultrafine Au cluster doping. Density functional theory calculations indicate that Au doping also promoted charge redistribution at the active site, increased the density of states near the Fermi energy level, stabilized the *COOH intermediate, and reduced the energy barrier of the rate-determining step. As a result, Au/Co-LDH delivers a CO evolution rate of 5610 mu mol g(-1) h(-1) toward CO2 reduction under visible light (lambda > 420 nm), which is 4 times and 22 times more active than the undoped one and Au nanoparticles, respectively. We believe that this work will provide an important implication for the development and optimization of photocatalysts for CO2 reduction.