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.