Ligand-Protected Au with a Novel Structure and Remarkable CO Electroreduction Performance.

A Au nanocluster with the composition of Au (p-MBT) (Ph P) (p-MBT=4-methylbenzenethiolate) is synthesized via direct reduction of gold-phosphine and gold-thiolate precursors. Single-crystal X-ray diffraction reveals that this Au nanocluster features a face-centered cubic (fcc) Au kernel, different from the well-known two-shell cuboctahedral arrangement in Au (Ph P) Cl . The Au cluster shows a wide optical absorption band with optical energy gap (E =1.28 eV). It is found that the exclusion of chloride is crucial for the formation of the title cluster, otherwise rod-like [Au (SR) (PPh ) Cl ] is obtained. The strategy to run synthetic reaction in the absence of halide leads to new members of phosphine/thiolate co-protected metal nanoclusters. The Au nanocluster exhibits high catalytic activity and selectivity for electrochemical reduction of CO to CO; the Faradaic efficiency (FE) reaches 94.1 % at -0.6 V vs. reversible hydrogen electrode (RHE).