Cooperation of Strong Electric Field and H 2 O Dissociation on Co 3 O 4 -Decorated SiC Rods for Photodriven CO 2 Methanation with 100% Selectivity.

Solar-driven methanation of carbon dioxide (CO 2 ) with water (H 2 O) has emerged as an important strategy for achieving both carbon neutrality and fuel production. The selective methanation of CO 2 was often hindered by the sluggish kinetics and the multiple competition of other C 1 byproducts. To overcome this bottleneck, we utilized a biomass synthesis method to synthesize SiC rods and then constructed a direct Z-scheme heterojunction Co 3 O 4 /SiC catalyst. The substantial difference in work functions between SiC and Co 3 O 4 served as a significant source of the charge driving force, facilitating the conversion of CO 2 to CH 4 . The high-valent cobalt Co(IV) in Co 3 O 4 acts as an active species to promote efficient dissociation of water. This favorable condition greatly enhanced the likelihood of a high concentration of electrons and protons around a single site on the catalyst surface for CO 2 methanation. DFT calculation showed that the energy barrier of CO 2 hydrogenation was significantly reduced at the Co 3 O 4 /SiC heterojunction interface, which changed the reaction pathway and completely converted the product from CO to CH 4 . The optimum CH 4 evolution rate of Co 3 O 4 /SiC samples was 21.3 μmol g -1 h -1 with 100% selectivity. This study has an important guiding significance for the selective regulation of CO 2 to CH 4 products in photocatalysis applications.