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

Exploring highly active, low-cost electrocatalysts for oxygen evolution reaction (OER) is of great significance but still a major challenge. Here, we synthesized Ni(OH)2@Ni(Fe)OOH with a sea urchin structure on nickel foam via a simple hydrothermal and subsequent soaking process. Experimental results indicate that incorporation of Fe into Ni(OH)2 is favorable for modulate the electronic structure, faster electron transfer and improved intrinsic activity, thereby leading to excellent OER activity. The optimized Ni(OH)2@Ni(Fe)OOH 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 along with high stability over 100 h, which is more active than benchmark RuO2 and sever control samples without introduction of Fe. More importantly, the overall water splitting system by using Ni(OH)2@Ni(Fe)OOH-100 as anode and Pt/C as the cathode only requires a cell voltage of 1.54 V to afford 10 mA cm-2. This work not only demonstrate the key factor of Fe doping, but also offers a new path for the development of NiFe-based OER catalysts.