Study on the Regulation of FeNi Catalysts Structure and OER Performance Induced by Lignosulfonate

Hydrogen production via water electrolysis holds promising application prospects. However, the oxygen evolution reaction (OER) at the anode encounters a higher energy barrier and sluggish kinetics due to its four-electron coupling transfer mechanism. This makes OER as the rate-limiting step in water electrolysis. Consequently, the development of efficient and stable OER electrocatalysts has become an urgent need. In this study, a sulfur-doped lignin-derived carbon-encapsulated iron-nickel catalyst (FeNi@SC) was prepared through hydrothermal self-assembly and high-temperature carbonization pyrolysis. This non-precious metal catalyst exhibited exceptional OER activity and long-term stability in alkaline media. Specifically, FeNi@SC achieved a low overpotential of 216 mV at a current density of 10 mA·cm⁻², significantly lower than the commercial precious metal catalyst Ru/C (320 mV) , and demonstrated remarkable stability over 100 h. Experimental results reveal that the synergistic effect of FeNi bimetal and sulfur doping promotes the OER process. Moreover, the strong coordination between the lignin framework and metal ions, coupled with the protective carbon coating, effectively prevents the leaching and agglomeration of FeNi alloy during the reaction. Our findings may provide a promising approach for developing highly active and stable OER catalysts, and also offer a strategy for the valorization of lignin.