Efficient electrocatalytic reduction of nitrate to ammonia over Mo2CTx micro-foam with rich edge sites

By employing a new method, we directly synthesized the first Mo2C nanosheet based micro-foam with rich edge-sites from the layered m-Mo2CTx precursor. Using this composite towards the electrocatalytic nitrate reduction to ammonia (NRA) at an optimized potential we measured an ammonia yield of 130.8 mmol h−1 g−1cat and a Faradaic Efficiency (FE) of 94.4%, much higher than that measured over the stacked layered structure (17.3 mmol h−1 g−1cat, 44%). This is due to both the large specific surface area of micro-foam and its rich Mo edge-sites, where the Mo and C atom layers are alternatively stacked. Compared with the pure Mo atoms on the basal plane of Mo2C, the Mo edge-sites show a more appropriate bonding with the N atoms, which can facilitate the hydrogenation of N* sites. The MoCx can be a good catalyst for NRA by regulating the coordination environment of Mo atoms.