Molecular-level electrocatalytic CO₂ reduction reaction mediated by single platinum atoms

The activation and transformation of H₂O and CO₂ mediated by electrons and single Pt atoms is demonstrated at the molecular level. The reaction mechanism is revealed by the synergy of mass spectrometry, photoelectron spectroscopy, and quantum chemical calculations. Specifically, a Pt atom captures an electron and activates H₂O to form a H-Pt-OH^- complex. This complex reacts with CO₂via two different pathways to form formate, where CO₂ is hydrogenated, or to form bicarbonate, where CO₂ is carbonated. The overall formula of this reaction is identical to a typical electrochemical CO₂ reduction reaction on a Pt electrode. Since the reactants are electrons and isolated, single atoms and molecules, we term this reaction a molecular-level electrochemical CO₂ reduction reaction. Mechanistic analysis reveals that the negative charge distribution on the Pt-H and the -OH moieties in H-Pt-OH^- is critical for the hydrogenation and carbonation of CO₂. The realization of the molecular-level CO₂ reduction reaction provides insights into the design of novel catalysts for the electrochemical conversion of CO₂.