Electrocatalytic CO2 Reduction with Atomically Precise Au13 Nanoclusters: Effect of Ligand Shell on Catalytic Performance

High Resolution Image Download MS PowerPoint Slide Supported gold nanoclusters of the formula [Au 13 (L) 5 Cl 2 ] 3+ where L = N -heterocyclic carbene (NHC) or phosphine ligands are examined in the electrocatalytic CO 2 reduction reaction (eCO 2 RR) in a membrane electrode assembly cell configuration. Gold nanoclusters bearing bis NHC ligands are shown to exhibit improved catalytic performance compared with diphosphine-stabilized nanoclusters after activation at the optimum treatment temperatures. The thermal properties of the nanoclusters are shown to have a significant impact on their catalytic activity. Thermogravimetric analysis, UV–vis absorption spectroscopy, and X-ray photoelectron spectroscopy revealed that thermal treatment of [Au 13 (diphosphine) 5 Cl 2 ] 3+ nanoclusters results in complete loss of diphosphine ligands while [Au 13 ( bis NHC) 5 Cl 2 ] 3+ nanoclusters show stepwise and partial removal of bis NHC ligands. We propose that the partial removal of bis NHC ligands enables efficient activation of [Au 13 ( bis NHC) 5 Cl 2 ] 3+ clusters while conserving the core structure. This leads to the implication that intact clusters retaining at least some ligands in their coordination environment are more active than ligand-free clusters.