Thin Copper-Based Film for Efficient Electrochemical Hydrogen Production from Neutral Aqueous Solutions

Here, we report a water-soluble copper(II) complex acting as a hydrogen evolution catalyst in a neutral aqueous solution, which could be further developed to form water reduction material through electrodeposition. The material with extremely low loading of 33 μg Cu cm–2 showed impressive TON value of 5876 and TOF of 734 h–1 in 8 h CPE experiment in a neutral phosphate buffer solution. In X-ray photoelectron spectroscopy (XPS), the high-resolution C 1s peak is corresponding to a C═C bond at 284.8 eV, C–N bond at 285.6 eV, C–O bond at 286.4 eV, and two different types of nitrogen configurations at around 398.5 and 399.9 eV are ascribed to pyridinic C═N and tertiary amine C–N bonds, respectively, which implies that the ligand might be incorporated into the copper active material. It is assumed that the presence of the ligand has an influence on the activity and stability of the deposit.