Hydrogen Bubble-Assisted One-Step Electrodeposition of Cu, Ni, and P toward Electrocatalytic Water Oxidation

Development of low-cost and highly abundant transition metal-based electrocatalysts for oxygen evolution reaction (OER) activity with low overpotential and high stability is desired for the utilization of electrolytic water-splitting cells to generate hydrogen (H2) fuel. The electrocatalytic activity could be further improved with the fabricated catalyst possessing microporous structures. In this study, binder-free hydrogen bubble-assisted electrodeposition of Cu, Ni, and phosphorous over a Cu sheet (CuNiP@Cu sheet) electrode was constructed. Three electrodeposition solutions consisting of 3:1, 1:1, and 1:3 mole ratios of Cu to Ni and 0.50 M sodium hypophosphite were utilized to produce electrodes under a range of electrodeposition potentials from −2.0 to −9.0 V vs Hg/Hg2SO4 so as to control the rate of hydrogen bubble template generation. The optimum performance for the OER in 1.0 M KOH solution was achieved using the electrode [i.e., CuNiP@Cu (1:1)] generated from an electrodeposition solution consisting of 1:1 mole ratio of Cu to Ni at −4.0 V vs Hg/Hg2SO4 for 5–20 min, which demonstrated a low overpotential value of 318 mV to achieve 10 mA/cm2 current density with a Tafel slope of 100 mV/dec. The potentiodynamic studies of the electrode showed minimal change in the overpotential value for the OER even after 786 cycles at a scan rate of 200 mV/s. The stability was also confirmed with the potentiostatic studies in which the electrode was found to be stable for 20 h of the experimental time. The outcomes suggest that low-cost, readily synthesized, and binder-free hydrogen bubble-assisted one-step electrodeposited microporous electrocatalysts hold excellent features toward the OER.