Cooperation of Strong Electric Field and H₂O Dissociation on Co₃O₄-Decorated SiC Rods for Photodriven CO₂ Methanation...

Solar-driven methanation of carbon dioxide (CO₂) with water (H₂O) has emerged as an important strategy for achieving both carbon neutrality and fuel production. The selective methanation of CO₂ was often hindered by the sluggish kinetics and the multiple competition of other C₁ byproducts. To overcome this bottleneck, we utilized a biomass synthesis method to synthesize SiC rods and then constructed a direct Z-scheme heterojunction Co₃O₄/SiC catalyst. The substantial difference in work functions between SiC and Co₃O₄ served as a significant source of the charge driving force, facilitating the conversion of CO₂ to CH₄. The high-valent cobalt Co(IV) in Co₃O₄ 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 CO₂ methanation. DFT calculation showed that the energy barrier of CO₂ hydrogenation was significantly reduced at the Co₃O₄/SiC heterojunction interface, which changed the reaction pathway and completely converted the product from CO to CH₄. The optimum CH₄ evolution rate of Co₃O₄/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 CO₂ to CH₄ products in photocatalysis applications.