Ligand-Shell Engineering of a Au-28 Nanocluster Boosts Electrocatalytic CO2 Reduction

Subtle tailoring of gold nanoclusters (NCs) could significantly change their physicochemical properties. However, direct comparison of the catalytic performance of gold NCs with identical metal cores but distinct ligand shells is rarely elucidated. In this work, a novel gold NC, Au-28(C2B10H11S)(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 to that of 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 better catalytic activity for the electrochemical reduction of CO2 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.