Interplay of In–O Bond Activation and Stabilization toward an Efficient and Stable CO 2 Hydrogenation to Methanol

Catalyst structure manipulation at the atomic level is important in regulating the catalytic performance. Herein, single Cr atom doping in In 2 O 3 is shown to modulate the In–O bond with improved performance in CO 2 hydrogenation to methanol. An “asymmetric site effect” concept is proposed to interpret the function of Cr doping, wherein Cr stimulates directly coordinated oxygens to form Cr and In confined oxygen vacancies as active sites for enhancing CO 2 activation and lowering the energy barrier of the HCOO* to HCOOH* transformation (the rate-determining step). Meanwhile, Cr assists in maintaining the structure stability and inhibits the over-reduction of In 2 O 3 through tethering nearby oxygen atoms. Cr–In 2 O 3 catalyst exhibits a CO 2 conversion of 9.4% and CH 3 OH selectivity of 92.0% under reaction conditions of 250 °C and 5 MPa, along with a long-term stability over 500 h on-stream testing. This study demonstrates a paradigm for the modulation of In–O in In 2 O 3 to break the trade-off between the reactivity and stability of the CO 2 hydrogenation reaction.