Electrochemically Synthesized Bis(diimino)metal Coordination Nanosheets as Ultrastable Electrocatalysts for Hydrogen Evolution Reaction

Bis(diimino)metal (MDI) nanosheets (M = Ni, Co, Cu) are synthesized within a few minutes on indium tin oxide (ITO), glassy carbon (GC), and carbon paper (CP) by electro-oxidation of an aqueous solution of metal ions, hexaaminobenzene trihydrochloride, and ammonia. Thin films of these materials are firmly immobilized directly on the substrate. Their PXRD patterns are similar to those prepared by chemical oxidation, indicating considerable crystallinity. Electrocatalytic activities of MDIs on GC in hydrogen evolution reaction were investigated using rotating disk voltammetry. NiDI affords the lowest overpotential for HER among known coordination nanosheet (CONASH) catalysts and offers high catalytic robustness.