Multiple CO reduction mediated by heteronuclear metal carbide cluster anions RhTaC.

Noble metals dispersed on transition-metal carbides exhibit extraordinary activity in CO catalytic conversion and bimetallic carbides generated at the interface were proposed to contribute to the observed activity. Heteronuclear metal carbide clusters (HMCCs) that compositionally resemble the bimetallic carbides are suitable models to get a fundamental understanding of the reactivity of the related condensed-phase catalysts, while the reaction of HMCCs with CO has not been touched in the gas phase. Herein, benefiting from the newly designed double ion trap reactors, the reaction of laser-ablation generated and mass-selected RhTaC clusters with CO was studied. The experimental results identified that RhTaC can reduce four CO molecules consecutively and generate the product RhTaCO. The pivotal roles of Rh-Ta synergy and the C ligand in driving CO reduction were rationalized by theoretical calculations. The presence of an attached CO unit on the product RhTaCO was evidenced by the collision-induced dissociation experiment, providing a fundamental strategy to alleviate carbon deposition under a CO atmosphere at elevated temperatures.