Highly Selective Hydrogenation of CO_2 to Ethanol via Designed Bifunctional Ir_1-In_2O_3 Single-Atom Catalyst

摘要

Recently, CO_2 hydrogenation for the controlled growth of the carbon chain to produce high-value C_2 or C_(2+) products has attracted great interest, where achieving high selectivity for a specific product remains a challenge, especially for ethanol. Herein, we have designed a bifunctional Ir_1-In_2O_3 single-atom catalyst, integrating two active catalytic centers by anchoring the monatomic Ir onto the In_2O_3 carrier. This Ir_1-In_2O_3 single-atom catalyst is efficient for the hydrogenation of CO_2 in liquid, yielding a high selectivity for ethanol (>99%) with an excellent initial turnover frequency (481 h~(-1)). Characterization shows that the isolated Ir atom couples with the adjacent oxygen vacancy forming a Lewis acid-base pair, which activates the CO_2 and forms the intermediate species of carbonyl (CO*) adsorbed on the Ir atom. Coupling this CO* with the methoxide adsorbed on the In_2O_3 forms a C-C bond. The strategy of this effective bifunctional single-atom catalyst by synergistically utilizing the distinct catalytic roles of the single-atom site and the substrates provides a new avenue in catalyst design for complex catalysis.