[AuAg26(SR)18S]- Nanocluster: Open Shell Structure and High Faradaic Efficiency in Electrochemical Reduction of CO2 to CO.

ABSTRACT

For atomically precise metal nanoclusters, distinctive molecular architectures and promising applications are urgently required to be intensively explored. Herein, we have first reported the open shell structure of the [AuAg26(S-Adm)18S]- nanocluster and its application in the electrochemical reduction of CO2. The X-ray crystal structure of the AuAg26 nanocluster is composed of a AuAg12 icosahedron kernel and a Ag14(SR)18S open shell. The shell includes a Ag6(SR)3S, a Ag5(SR)6, and three Ag(SR)3 motifs. It is the first time twisty propeller-like Ag5(SR)6 and trefoil-like Ag6(SR)3S motifs in metal nanoclusters have been observed. Due to the novel open shell configuration of Ag14(SR)18S, four triangular facets of the kernel are exposed. The AuAg26 nanocluster shows excellent catalytic activity in the electrochemical reduction of CO2 to CO. The Faradaic efficiency of CO is up to 98.4% under -0.97 V. The electrochemical in situ infrared study and DFT calculations demonstrate that the open shell structure of the AuAg26 nanocluster is beneficial to the forming of intermediate COOH* in the electrochemical reduction of CO2 to CO.