Dinuclear Copper Complex for High-Rate Hydrogen Evolution Under Neutral Aqueous Conditions

The development of an efficient and stable electrocatalyst for the hydrogen evolution reaction (HER), based on earth-abundant components, represents a crucial step toward cost-effective and environmentally friendly hydrogen production. This study presents the utilization of a dinuclear copper catalyst, denoted as [Cu-Gly-SB] (Complex 1), for HER under both aqueous and non-aqueous conditions. In non-aqueous settings, the catalyst achieves excellent HER performance, requiring only a 270 mV overpotential when acetic acid is used as the proton donor. Notably, in fully aqueous conditions, complex 1 attains a remarkable current density of 18.8 mA ⋅ cm⁻² at −0.7 V vs. RHE in cyclic voltammetry. The k_obs value of ≈2.7×10⁴ s⁻¹ in aqueous solution at pH 7.0 further underlines the superior catalytic performance of 1, outperforming most non-noble-metal molecular catalysts functioning in fully aqueous solutions. The robust stability of 1 is demonstrated through controlled potential electrolysis (CPE) over a span of 48 hours, achieving an impressive catalytic current of 11.0 mA ⋅ cm⁻² at −0.39 V. Moreover, the catalytic current gradually increases with higher reduction potentials, reaching a substantial 100 mA ⋅ cm⁻² at an overpotential of 590 mV during CPE >48 hours. Thorough characterizations further confirm the molecular nature of the catalyst.