Rapid synthesis of sea urchin-like Ni(OH)2@Ni(Fe)OOH electrocatalysts for the oxygen evolution reaction

Abstract

Exploring highly active, low-cost electrocatalysts for the oxygen evolution reaction (OER) is of great significance but still a major challenge. Herein, we synthesized Ni(OH)₂@Ni(Fe)OOH with a sea urchin-like structure on a nickel foam via a simple hydrothermal and subsequent soaking process. Experimental results indicate that incorporation of Fe into Ni(OH)₂ is favorable for modulating the electronic structure as well as achieving faster electron transfer and improved intrinsic activity, thereby leading to excellent OER activity. The optimized Ni(OH)₂@Ni(Fe)OOH electrocatalyst exhibits superior OER activity with overpotentials of 245 and 310 mV at 10 and 100 mA cm⁻², respectively, and a small Tafel slope of 40.7 mV dec⁻¹ and high stability over 100 h, which is more than that of benchmark RuO₂ and several control samples without the introduction of Fe. More importantly, the overall water splitting system using Ni(OH)₂@Ni(Fe)OOH-100 as the anode and Pt/C as the cathode only requires a cell voltage of 1.54 V to afford a current density of 10 mA cm⁻². This work not only demonstrates the key factor of Fe doping, but also offers a new path for the development of NiFe-based OER catalysts.