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Revealing and regulating the intricate reaction mechanism of direct CO 2 hydrogenation to higher alcohols (C 2+ OH), especially for the crucial C–C coupling step, is still a great challenge. Herein, the specific reaction network on Co 2 C and CuZnAl multifunctional tandem catalysts is elucidated by designing subtly surface adsorption–desorption reactions, in situ chemical transient kinetics, and theory calculations. The key C–C coupling step for the formation of C 2+ OH over the sole Co 2 C catalyst was the insertion of CO into R-CH x, while the reaction mechanism can be modulated to the coupling of R-CH 2 and CHO with a lower energy barrier on the tandem catalyst (Co 2 C||CuZnAl). R-CH 2 was derived from the hydrogenation dissociation of olefins and coupled with the CHO from formate hydrogenation at the Cu/ZnAl 2 O 4 interface. Such multifunctional tandem catalysts exhibited a high space–time yield of C 2+ OH of 2.2 mmol g –1 h –1 . This work provides an effective strategy for studying complex mechanisms, contributing to the precise design of highly efficient catalysts and the optimization of reaction pathways.
Zhang et al. (Wed,) studied this question.