Hydrogen production in a neutral aqueous solution with a water-soluble copper complex

•A water-soluble copper electrocatalyst 1 was developed for hydrogen production.•Electrocatalyst 1 performs in a neutral aqueous solution at a low overpotential.•Stable copper complex functions as a molecular electrocatalyst.•Low overpotential & water solubility of 1 facilitates a photocatalytic application.

A water-soluble polypyridine copper complex Cu(dpp)(ClO4)2 (1, dpp = 2,9-di(pyridin-2-yl)-1,10-Phenanthroline) enables to electrocatalyze H2 generation from neutral phosphate buffer solution at a relatively low overpotential of 520 mV vs. SHE. Sustained proton reduction catalysis occurs at glassy carbon electrode at −1.4 V vs. SHE for 2 h to give H2 with TONs of 734 mol H2 (mol catalyst)−1 cm−2 and 95% Faradaic yield. CVs, UV-Vis spectra, SEM, EDX and Tyndall analysis reveals that 1 has the desired stability and functions as a molecular electrocatalyst under the conditions. Due to the relatively low overpotential and high stability, light-driven hydrogen production based on 1 were also carried out with a TONs of 6 mol H2 (mol catalyst)−1 in an aqueous solution.

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