High-Performance Electrohydrogenation of N₂ to NH₃ Catalyzed by Multishelled Hollow Cr₂O₃ Microspheres under Ambient Conditions

Electrohydrogenation of N 2 to NH 3 is emerging as an environmentally benign strategy to tackle the issues associated with the energy-intensive, CO 2 -emitting Haber–Bosch process. However, the method is severely challenged by N 2 activation and needs efficient N 2 reduction reaction (NRR) catalysts. Here, we report that multishelled hollow Cr 2 O 3 microspheres (MHCMs), which are synthesized by a facile synthetic route, can serve as efficient and selective non-noble metal electrocatalysts for NRR. In 0.1 M Na 2 SO 4 solution, the MHCMs achieve a high Faradaic efficiency (6.78%) and a large NH 3 yield (25.3 μg h –1 mg cat –1 ) at −0.9 V vs reversible hydrogen electrode. The MHCMs also exhibit high stability during the reaction. Density functional theory calculations suggest that NRR over MHCMs occurs via both distal associative and partially alternative routes.