Unveiling the Role of Co3InC0.75 Bimetallic Carbide in CO2 Hydrogenation to Methanol

Bimetallic Co/In₂O₃ catalysts are known for their promising performance in the hydrogenation of CO₂ to methanol, often undergoing structural transformation during a prolonged induction period. Co₃InC_0.75 is frequently observed after this process, yet its catalytic role has remained elusive due to the lack of phase-pure materials and mechanistic clarity. Herein, we report the synthesis of highly crystalline, phase-pure Co₃InC_0.75 via a one-step gas-phase carburization method. Catalytic tests reveal that Co₃InC_0.75 acts as an active phase for CO₂ selective hydrogenation, achieving a methanol space-time yield of 0.69 g_MeOH g_cat^–1 h^–1with a selectivity of 70.1% at 280 °C, 5 MPa, H₂/CO₂ ratio of 3:1, and a gas hourly space velocity of 24,000 cm_STP³ g_cat^–1 h^–1, and remains stable over 100 h of continuous operation. In situ characterizations and theoretical studies confirm that the carbide surface promotes direct CO₂ dissociation and sequential hydrogenation via an RWGS-mediated pathway. This work identifies Co₃InC_0.75 as a previously overlooked active phase and expands the design landscape for carbide-based CO₂ hydrogenation catalysts.