Two-Dimensional Silver Cyanamide Nanocrystals toward CO2 Reduction

Metal cyanamides have an organic–inorganic hybrid structure similar to MOFs, which are expected to possess interesting catalytic properties. However, the structural complexity of these compounds sets up a big barrier to realize shape manipulation and further understanding on the structure–activity relationship. Here, we describe seed-mediated colloidal synthesis as a facile approach to obtain Ag2NCN near-monodisperse nanocrystals (NCs: nanorods, nanowires, and nanosheets) and their related CO2 catalytic activity. The control experiment unveiled the prominent role of the anisotropy for quasi-linear [NCN]2– anions in obtaining the desired growth order of different crystal planes. The formic acid production of nearly 20% Faradaic efficiency is observed when the as-prepared Ag2NCN NCs were tested for electrocatalytic CO2 reduction reactions. The exposed (200) planes exhibit evident higher catalytic activity compared to other planes, showing morphology-dependent activity. Our result reveals that the anisotropic structure of ions leads to their preferential growth of the NCs and thus may have greater implications for the shape-controlled synthesis of complex ions containing compounds and their related catalytic activity.