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 (NiOx-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 (0.6M, pH 9.2), and the results showed that the NiOx-Tris electrode exhibits a better catalytic activity over the catalyst (NiOx-aqua) that was derived from Ni2+ salts. In detail, the NiOx-Tris ultrathin film achieved a stable catalytic current density of similar to 5.0 mA/cm(2) at 1.3 V versus a normal hydrogen electrode for OER in borate buffer solution. (C) 2018 Elsevier Ltd. All rights reserved.