Rapid in situ synthesis of sulfur-doped transition-metal oxyhydroxides by room temperature impregnation for advanced electrocatalytic splitting water

Methods for designing and synthesizing energy-efficient, time-saving, and economical electrocatalysts are important to advance the electrolysis of water for hydrogen production. The synthesis of new catalytic materials should be simple and convenient, have limited environmental impact, and deliver high catalytic activity. We present a simple method for an in situ synthesis of hydroxyl oxide nanosheet materials supported on nickel foam as the conductive support that is quick (procedure complete in 5 min), and operated at room temperature and pressure. This green and pollution-free preparation method forms a oxyhydroxide layer with more active sites on the nickel foam surface, while the self-supported nanosheet arrays ensure fast electron transfer and good sta-bility. The hydroxides electrodes exhibit excellent electrocatalytic performance in alkaline electrolytes, notably S-FeNiOOH as hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalyst with a current density of 100 mA cm-2 at 248 mV and 293 mV overpotential. When used as a catalyst for water splitting in a full cell, an applied voltage of only 1.81 V was required to achieve a current density of 100 mA cm-2 for the overall electrolysis of alkaline water that exhibits good durability. This work provides an effective strategy for the application of self-supporting electrodes composed of nanostructured arrays on conducting substrates, creating new opportunities in advanced materials that are important for both the hydrogen economy and environmental remediation.