Aluminum-induced direct electroless deposition of Co and Co-P coatings on copper and their catalytic performance for electrochemical water splitting

Co and Co-P coatings were prepared on copper using an aluminum-induced direct electroless plating method, the main feature of which was that a small part of the copper substrate was twined around by the aluminum foil during the plating process. Because of coupling the copper substrates with aluminum foils, Co coatings were obtained on copper from a reducing agent-free plating solution and Co-P coatings were obtained without activation step at room temperature. The electrochemical experiments demonstrated the coupled aluminum foils could shift the potential of copper substrates negatively, and also donate electrons for the reduction of cobalt ions in the alkaline plating solutions. The morphology and composition of the Co and Co-P coatings were characterized by scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Compared with Co coatings, the Co-P coatings had larger deposition rates and were consisted of finer grains. Co and Co-P coatings showed nearly the same oxygen-evolution reaction electrocatalytic performance in 1.0 M KOH solution, which was superior to that of platinum plate. While, the Co-P coatings exhibited better electrocatalytic performance for hydrogen-evolution reaction in 1.0 M KOH solution than the Co coating, and could reach a current density of 40 mA·cm−2 at overpotential of about 240 mV.