Self-supported Fe,Mn-CoCH/NF electrocatalyst for oxygen evolution reaction

The oxygen evolution reaction (OER), as the core half-reaction in water electrolysis (WE), plays a decisive role in determining the overall efficiency of hydrogen production. Cobalt carbonate hydroxide (CoCH) has recently emerged as a attractive material for alkaline OER due to its robust structural stability. In this study, urchin-like CoCH was employed as a precursor template to synthesize Fe and Mn co-modified CoCH catalyst on nickel foam (NF) through Mn-doping and surface Fe-modification strategies (recorded as Fe,Mn-CoCH/NF). This optimized hierarchical structure enhanced the exposure of active sites and facilitated faster electron/mass transport paths. The incorporation of Fe and Mn effectively regulated the position of d-band center and facilitated a more efficient lattice oxygen mechanism (LOM) for OER, thereby enhancing the intrinsic activity of the catalyst. Compared to the unmodified CoCH/NF, the Fe,Mn-CoCH/NF exhibited significantly improved OER catalytic activity, characterized by a substantially reduced overpotential (204 mV at 10 mA cm^-2) in alkaline electrolyte, alongside remarkable stability. Utilizing this catalyst, an overall water splitting (OWS) system was further developed, capable of driving efficient OWS at a low cell voltage (1.49 V at 10 mA cm^-2). Furthermore, the unique hierarchical structure of Fe,Mn-CoCH/NF contributed to mitigating electrochemical corrosion and the toxic effects of Cl^- during seawater electrolysis, enabling the catalyst to maintain excellent catalytic activity and stability even in alkaline seawater system.