Direct Observation of Electron Donation onto the Reactants and a Transient Poisoning Mechanism During CO Electroreduction on Ni Single Atom Catalysts.

Single atom catalysts (SACs) are an important class of materials that mediate chemical reduction reactions, a key subset of which is Ni within a carbon support for the electrochemical CO reduction reaction (CORR). However, how the metal atom/clusters and the carbon-based support act in concert to catalyze CORR is not well understood, with most reports attributing activity solely to the Ni-N/C moieties. To address this gap, we have undertaken a mechanistic investigation, employing in situ X-ray absorption spectroscopy (XAS) coupled with electrochemical studies and density functional theory (DFT) calculations to further understand how Ni single atoms work in conjunction with the nitrogen-doped carbon matrix to promote CORR to CO, and how the presence of impurities such as those present in CO-containing waste flue gases (including NO, and CN) changes the catalyst upon reduction.