A partial sulfidation approach that significantly enhance the activity of FeCo layered double hydroxide for oxygen evolution reaction

We report a partial sulfidation approach that effectively boosts the OER activity of FeCo-layered double hydroxides (LDH). It is found that the mild sulfurized FeCo-LDH nanosheets using Na₂S converted a portion of their surface metal-hydroxide bonds to metal-sulfur (-hydrosulfide) bonds without significantly altering their crystal structure. The sulfidation degree is controlled by Na₂S concentration for obtaining a moderately surface electronic configurations. Benefits from the regulated electronic configurations, the sulfurized FeCo-LDH nanosheets only require an overpotential of 281 mV to produce oxygen at 10 mA cm⁻² and their Tafel slope is 51.8 mV dec⁻¹, which are both lower than the 348 mV and 72.7 mV dec⁻¹ of pristine FeCo-LDH nanosheets. The sulfurized catalysts have sustained 12 h of operation without notable activity loss. This work can provide new insights into understanding the roles of metal-sulfur bonds for OER and offer an attractive strategy to design low cost but efficient OER catalysts.