On March 6th, a collaborative effort between the team of Sun Xiaoming and Zhou Daojin from Beijing University of Chemical Technology and the team of Professor Liu Bin from City University of Hong Kong resulted in a publication titled "10,000-h-stable intermittent alkaline seawater electrolysis" in the prestigious journal Nature.
Seawater electrolysis powered by renewable electricity provides an attractive strategy for producing green hydrogen. However, direct seawater electrolysis faces many challenges, primarily arising from corrosion and competing reactions at the anode caused by the abundance of halide ions (Cl−, Br−) in seawater. Previous studies on seawater electrolysis have mainly focused on the anode development, because the cathode operates at reducing potentials, which is not subject to electrode dissolution or chloride corrosion reactions during seawater electrolysis. However, renewable energy sources are intermittent, variable and random, which cause frequent start–shutdown operations if renewable electricity is used to drive seawater electrolysis. Herein, Xiaoming Sun Group first unveil dynamic evolution and degradation of seawater splitting cathode in intermittent electrolysis and, accordingly, propose construction of a catalyst’s passivation layer to maintain the hydrogen evolution performance during operation. An in situ-formed phosphate passivation layer on the surface of NiCoP–Cr2O3 cathode can effectively protect metal active sites against oxidation during frequent discharge processes and repel halide ion adsorption on the cathode during shutdown conditions. This work demonstrate that electrodes optimized using this design strategy can withstand fluctuating operation at 0.5 A cm−2 for 10,000 h in alkaline seawater, with a voltage increase rate of only 0.5% khr−1. The newly discovered challenge and the proposed strategy herein offer new insights to facilitate the development of practical seawater splitting technologies powered by renewable electricity.
Figure (A) Schematic illustration of cathodic oxidation and corrosion under intermittent water/seawater electrolysis cycles. (B, C) Quantitative analysis of cathodic oxidation potential under shutdown conditions. (D, E) Aberration-corrected electron microscopy images after start-stop cycles. (F) Stability test of the electrode under intermittent electrolysis conditions.
Original link: https://www.nature.com/articles/s41586-025-08610-1