A monolithic Co-FeCo8S8 electrode for stable anion exchange membrane water electrolyzer driven by fluctuating power supply

Integrating water electrolysis and green electricity offers a promising approach towards sustainable and clean energy. However, such a system demands electrodes that can swiftly and stably adapt to fluctuating power supply. Here, we developed a monolithic Co-FeCo8S8 electrode to realize robust water electrolysis under steady and fluctuated electricity owing to its strong interfacial bonding and unimpeded charge transfer between substrates and catalysts. The activated Co-FeCo8S8 electrode displays excellent oxygen evolution reaction performance with a small overpotential of 334 mV at 2,000 mA cm-2 and operates stably for 1,500 h at 500 mA cm-2. The assembled anion exchange membrane water electrolyzer needs a small cell voltage of 1.79 V at 1.0 A cm-2 and operates stably with a low voltage degradation rate of 0.115 mV h-1, surpass most reported electrolyzers. Notably, the electrolyzer shows rapid response and stable operation when coupled with fluctuating solar electricity. This work provides guidance for designing stable electrodes in practical scenarios with fluctuating power supply.