Pt-free NiCo electrocatalysts for oxygen evolution by seawater splitting

•NiCo alloys are synthesized by using organic solvents as reducing agents.•Organic solvents such as DEA, PG, ETA and MEG are optimized for NiCo preparation.•NiCo alloy electrocatalysts are prepared for OER from seawater splitting.•The resultant NiCo electrodes are robust and stable for seawater splitting.

Creation of robust and cost-effective electrocatalysts is a persistent objective for high-efficiency oxygen evolution from water splitting. I present here the one-step hydrothermal synthesis of a category of Pt-free NiCo alloy electrocatalysts assisted by a reduction process with diethanolamine, propanediol, ethanolamine or mono-ethylene gloycol. By optimizing assistant solvent species, the catalytic performances toward oxygen evolution reaction (OER) in seawater are maximized. The resultant NiCo electrocatalysts are featured with low onset overpotentials and large current densities for OER from seawater splitting. The large heterogeneous electron transfer rate constant (Koeff) and turnover frequency (TOF) suggest robust catalytic behaviors toward OER in real seawater. Additionally, the reasonable long-term stability of the optimal NiCo alloy electrode over 40 h in seawater further demonstrates that it is promising for oxygen evolution from splitting seawater.