A bio-inspired mononuclear manganese catalyst for high-rate electrochemical hydrogen production

[FeFe]-hydrogenase (H₂ase) catalyzes hydrogen evolution reactions (HERs), with an excellent performance that rivals that of platinum, the active site of which is built with crucial structural features required for efficient H-H bond formation. Herein, we report a mononuclear manganese complex (1) that contains a square pyramid coordination sphere and an intramolecular aniline as the proton relay, consistent with the crucial features of the active site in H₂ase. Benefitting from these features, complex 1 electrocatalyzes the HER with a turnover frequency (TOF) exceeding 10 000 s^-1 at -1.45 V (versus the ferrocenium/ferrocene couple) using anilinium tetrafluoroborate as a proton source. This work provides the first Mn-based functional model of H₂ase, serving as a new paradigm for a high performance, low cost, environmentally benign hydrogen production electrocatalyst.