Robust and selective electrochemical reduction of CO2: the case of integrated 3D TiO2@MoS2 architectures and Ti–S bonding effects

Abstract

Developing efficient and affordable catalysts toward electrochemical reduction of CO₂ to valuable chemicals is of great significance for energy and environmental sustainability, which can be efficaciously achieved by catalyst structure steering. In this study, we propose an ingenious strategy to modulate MoS₂ favorable for CO₂ reduction by fabricating an integrated three-dimensional (3D) TiO₂@MoS₂ architecture containing Ti–S bonds, the formation of which, revealed by density functional theory calculations, has changed the electric properties of the MoS₂ layer and the adsorption characters of Mo exposed edges. The modulated MoS₂ is vigorous for CO₂ reduction due to the decrease of both the binding energy of CO₂ and the energy barriers of CO₂ reduction reaction pathways. Experimentally, the integrated 3D TiO₂@MoS₂ architectures can act as efficient and stable catalysts for selective reduction of CO₂ to CO. The optimized composite showed a negligible onset overpotential of 100 mV for CO formation in KHCO₃ solution, and a maximum faradaic efficiency of ∼82% for CO at −0.7 V vs. RHE with a large partial current density for CO of 68 mA cm⁻². Additionally, the integrated 3D electrodes exhibited superior stability during CO₂ reduction. This study will shed light on the modification of electrocatalysts for efficient CO₂ reduction through structure steering.