Structure–property relationship of atomically-precise silver acetylide clusters in the electroreduction of CO2†

The synthesis of a library of silver acetylide cluster catalysts for the electroreduction of CO₂ is described. The methodology relies on a one-step reaction between terminal alkynes and an aqueous silver ammoniacal solution, producing a library of clusters isolated via simple filtration. Their catalytic properties in the CO₂ electroreduction reaction were thoroughly assessed, focussing on faradaic efficiency, overpotential, turnover frequency and their structural features characterised via powder XRD, XPS and electrochemical methods. It was found that the chemical structure of the ligand had a strong impact on the overall crystallinity of the cluster, and a correlation between crystallinity, overpotential and selectivity was established. Our study points to the importance of the number of Ag(0) active sites formed under reducing conditions, which are directly linked to the ligand chemical structure, while the overpotential and selectivity are rather dictated by the degree of order (crystallinity) of the whole cluster.