Ultrathin SiC Nanosheets with High Reduction Potential for Improved CH4 Generation from Photocatalytic Reduction of CO2

Exploitation of low-cost and efficient photocatalysts for selective reduction of CO2 into fuels such as methane or methanol is highly desired in the field of solar-to-fuel conversion. Herein, ultrathin SiC nanosheets (NSs) with high crystallinity are prepared using two-dimensional reduced graphene oxide as sacrificial template. The ultrathin feature of SiC NSs readily shortens the migration distance of photoexcited carriers, thereby reducing the recombination probability and providing more energetic electrons to participate in CO2 reduction. Consequently, both the yield (3.11 mu mol h(-1) g(-1)) and selectivity (90.6%) of CH4 over SiC NSs demonstrate dramatic improvements in comparison with that of micro-size SiC (0.76 mu mol h(-1) g(-1), 77.9%) and commercial TiO2 (1.46 mu mol h(-1) g(-1), 61.0%). The initial absorption and activation of CO2 molecules on the surface of SiC NSs is confirmed by the in situ diffuse reflectance infrared Fourier transform spectroscopy. The SiC NSs can promote the deep reduction of carbon intermediate into CH4 thanks to the strong reduction potential of photoexcited electrons. This work not only proves ultrathin SiC NSs to be a promising photocatalyst for CO2 reduction, but also provides novel insights into deep photoreduction of CO2 to CH4.