Engineered Superhydrophilic/Superaerophobic Array Electrode Composed of NiMoO4@NiFeP for High-Performance Overall Water/Seawater Splitting

Abstract

Exploring advanced electrocatalysts for overall water/seawater splitting is significant to massive green hydrogen production. Here, we report a novel self-sacrificing template strategy to fabricate a heterostructured NiMoO4@NiFeP electrode with superwetting properties as a bifunctional electrocatalyst for overall water/seawater splitting. Such an electrode exhibits superior intrinsic activity, more accessible active sites, effective charge transfer, and weak adhesion of gas bubbles. Its excellent corrosion resistance and superhydrophilic/superaerophobic nanoarrayed architecture ensure its catalytic performance under harsh seawater conditions. Accordingly, the electrode requires overpotentials of only 282 and 195 mV at 100 mA cm–2 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 1 M KOH seawater together with its robust durability. Operando Raman spectroscopy together with ex situ characterization technologies reveal that NiMoO4@NiFeP was rapidly reconstructed to active Fe-doped β-Ni oxyhydroxides (β-Fe/NiOOH) during alkaline OER. Density functional theory calculations further disclose that Fe doping can optimize the energy barrier and modulate the d-band center of the catalyst, intrinsically boosting the OER performance. Consequently, the NiMoO4@NiFeP-assembled electrolyzer requires a voltage of 1.71 V at 100 mA cm–2 for seawater splitting and can stably maintain over 200 h without producing any hypochlorite. Our work holds great promise for constructing efficient non-noble-metal bifunctional electrodes toward water/seawater electrolysis applications.