An ultrathin nickel-based film electrodeposited from a Ni-Tris molecular precursor for highly efficient electrocatalytic water oxidation

Water splitting is one of the important and effective routes to produce hydrogen as applicable alternative to conventional fossil fuels. As we all know, oxygen evolution reaction (OER) is a key and restricted part of the overall water-spitting process. Highly efficient electrocatalysts are essential components to accelerate the rate of the OER and lower the overpotential. In this paper, an ultrathin nickel-based film on FTO (NiO_x-Tris electrode) was prepared through five cycles of cyclic-voltammetry electrodeposition from a 0.1 M borate buffer solution (pH 9.2) that contained a molecular nickel complex as a precursor. The activity of the as-prepared catalyst film for OER was measured in near-neutral borate buffer solution (0.6 M, pH 9.2), and the results showed that the NiO_x-Tris electrode exhibits a better catalytic activity over the catalyst (NiO_x-aqua) that was derived from Ni²⁺ salts. In detail, the NiO_x-Tris ultrathin film achieved a stable catalytic current density of ∼5.0 mA/cm² at 1.3 V versus a normal hydrogen electrode for OER in borate buffer solution.