Ligand-Protected Au55 with a Novel Structure and Remarkable CO2 Electroreduction Performance

A Au-55 nanocluster with the composition of [Au-55(p-MBT)(24)(Ph3P)(6)](SbF6)(3) (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-55 nanocluster features a face-centered cubic (fcc) Au-55 kernel, different from the well-known two-shell cuboctahedral arrangement in Au-55(Ph3P)(12)Cl-6. The Au-55 cluster shows a wide optical absorption band with optical energy gap (E-g=1.28 eV). It is found that the exclusion of chloride is crucial for the formation of the title cluster, otherwise rod-like [Au-25(SR)(5)(PPh3)(10)Cl-2](2+) 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-55 nanocluster exhibits high catalytic activity and selectivity for electrochemical reduction of CO2 to CO; the Faradaic efficiency (FE) reaches 94.1 % at -0.6 V vs. reversible hydrogen electrode (RHE).

Automated summary

The study successfully synthesized an Au-55 nanocluster, which exhibited high catalytic activity and selectivity for the electrochemical reduction of CO2 to CO. The research also demonstrated that carrying out synthetic reactions in the absence of halide can lead to the formation of phosphine/thiolate co-protected metal nanoclusters.