Ligand-Shell Engineering of a Au28 Nanocluster Boosts Electrocatalytic CO2 Reduction.

Subtle tailoring of gold nanoclusters (NCs) could significantly impart their physicochemical properties. However, direct comparison of the catalytic performance of gold NCs with identical metal core but distinct ligand shells is rarely elucidated. In this work, a novel gold NC, Au 28 (C 2 B 10 H 11 S) 12 (tht) 4 Cl 4 ( Au 28 -S ), was isolated by a facile self-reducing synthesis. Au 28 -S adopts an identical Au 28 metal framework with the reported alkynyl-protected Au 28 -C . The different protective layers lead to distinctions in their electronic structure and optical properties. Furthermore, Au 28 -S shows more excellent catalytic activity for the electrochemical reduction of CO 2 to CO. Theoretical calculations identified the active sites and shed light on the catalytic mechanism to elucidate the different catalytic performances. This work provides an ideal platform to study the protective layer-activity relationship of gold NCs, and may also provide guidance in the design of metal NC-based catalysts.