Oxygen evolution reaction (OER) is a core and rate-control process for the electrocatalytic water splitting. Due to the high energy barrier, the OER kinetics and overall water splitting efficiency are limited. Herein, bimetallic sulfide Co₉S₈-Ni₃S₂/SN-C catalyst was successfully prepared via oxidative ammonolysis of renewable lignosulfonates, and showed excellent electrocatalytic OER performance. The complex structure of sodium lignosulfonate modified with NHCO groups was investigated by comprehensive characterization, and the structural evolution mechanism of the precursor during pyrolysis and carbonization was revealed, with the formation of the active center Co₉S₈-Ni₃S₂ revealed as well. The strong binding of the modified lignin-carbon with metals enhanced the dispersion of active sites Co₉S₈ and Ni₃S₂. The close interaction between Co₉S₈-Ni₃S₂ and the defect doping of N onto the carbon carrier effectively regulated the surface electronic structure, and optimized the adsorption of the reaction intermediate, and thus improved the electrochemical OER reaction performance. The OER activity of Co₉S₈-Ni₃S₂/SN-C catalyst reached the highest level when m(H₂O₂)/m(LS) = 1.5 for oxidative ammonolysis, and showed a lower overpotential (350 mV) than that of commercial Ru/C catalyst (420 mV) at a current density of 50 mA·cm⁻². This work provides an insight into the directional regulation of lignin-based functional materials and its development for highly efficient and stable OER electrocatalysis.

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.

Rechargeable sodium-ion batteries usually suffer from accelerated electrode destruction at high temperatures and high synthesis costs of electrode materials. Therefore, it is highly desirable to explore novel organic electrodes considering their cost-effectiveness and large adaptability to volume changes. Herein, natural biomass, pristine lignin, is employed as the sodium-ion battery anodes, and their sodium storage performance is investigated at room temperature and 60 ℃. The lignin anodes exhibit excellent high-temperature sodium-ion battery performance. This mainly results from the generation of abundant reactive sites (C=O) due to the high temperature-induced homogeneous cleavage of the C_β–O bond in the lignin macromolecule. This work can inspire researchers to explore other natural organic materials for large-scale applications and high-value utilization in advanced energy storage devices.