Tri-metallic phytate in situ electrodeposited on 3D Ni foam as a highly efficient electrocatalyst for enhanced overall water splitting

Abstract

An interconnected catalyst architecture has been in situ fabricated on Ni foam through facile electrochemical corrosion in sodium phytate containing Co and Fe metal ions. The introduction of Co and Fe in the N-phy system enables the phytate ions to link more active metal ions and then creates abundant catalytic sites to enhance the water oxidation performance and simultaneously to improve the overall water splitting activity. As a result, this self-supported C6FN-phy electrode delivers a high current density of 200 mA cm⁻² at an overpotential of 285 mV for oxygen production and at 327 mV for hydrogen evolution in 1 M KOH, surpassing most catalysts recently reported. Besides, the electrocatalytic activity can be maintained for at least 45 h with a subtle potential increase, illustrating the versatile and practical application in industry. What's more, we achieve a current density of 100 mA cm⁻² at 1.91 V by using C6FN-phy as the cathode and anode for overall water splitting, which is well comparable to the integrated performance of Pt/C and RuO₂. Most importantly, multiple alternating chronopotentiometric tests of C6FN-phy as both the OER and the HER catalyst also verify the high availability and robust durability of the electrode as a true bifunctional electrocatalyst.