Interplay of In-O bond activation and stabilization for a high-performance CO2 hydrogenation to methanol

Abstract Precise manipulation of catalyst structure at atomic level holds the key to regulating the catalyst performance. Herein, we show that single Cr atom doping in In₂O₃ can modulate the In-O bond with significantly improved performance in CO₂ hydrogenation to methanol. A “distance effect” concept is proposed to interpret the function of Cr doping, wherein Cr stimulates the directly coordinated oxygen to form Cr and In confined oxygen vacancy (Ov) active sites for the enhancement of CO₂ activation and lowering the energy barrier for the HCOO* to H₂COO* transformation (the rate-determining step). In addition, Cr assists in maintaining the structure stability and inhibits the over-reduction of In₂O₃ through the tethering of nearby oxygen atoms. The Cr-In₂O₃ catalyst exhibits a CO₂ conversion of 9.4% and CH₃OH selectivity of 92.0% under the reaction conditions of 250°C, 5 MPa, and 3000 mL·gcat⁻¹·h⁻ ¹, along with a remarkable stability over 500 h on-stream testing. This study demonstrates a new paradigm for the modulation of In-O bonds in In₂O₃-based catalysts to break the trade-off between the reactivity and stability of the CO₂ hydrogenation reaction.