In Situ-Fabricated 2D/2D Heterojunctions of Ultrathin SiC/Reduced Graphene Oxide Nanosheets for Efficient CO2 Photoreduction with High CH4 Selectivity.

Abstract

Photoreduction of CO2 into fuel molecules such as CH4 represents a promising route to simultaneously explore renewable energy and alleviate global warming. However, the implementation of such a process is hampered by low product yields and poor selectivity. A 2D/2D heterojunction of ultrathin SiC and reduced graphene oxide (RGO) nanosheets was fabricated in situ for efficient and selective photoreduction of CO2 . Ultrathin SiC suppresses significant charge recombination in the bulk phase, thus providing more energetic electrons. The robust 2D/2D heterojunction allows fast transfer of energetic electrons from SiC to RGO. Combining the vital role of RGO in facilitating CO2 activation, the optimized SiC/RGO exhibits an electron-transfer rate of 58.17 μmol h-1 g-1 towards CO2 reduction, 2.7 times that of pure SiC (20.25 μmol h-1 g-1 ). About 92 % of the transferred electrons from SiC are devoted to generating CH4 (6.72 μmol h-1 g-1 ). Such high efficiency and selectivity are mainly a result of the densely accumulated energetic electrons within RGO, which facilitate the eight-electron process to produce CH4 . This work will inspire the design of catalyst/cocatalyst systems for efficient and selective photoreduction of CO2 .