4. Conclusions

In situ coupling strategy of CoFe alloy and CoxN heterojunction encapsulated and embedded in the nitrogen-doped lignin-derived carbon CoFe-CoxN@NC was provided to create a novelty highly active and stable electrocatalyst for oxygen evolution reaction. Biorefinery lignin was first carboxylated to improve its solubility and precisely coordinated with metal ions to form the coordination polymer precursor, that promoted the dispersion of metal active component and the encapsulated grapheme lawyer of CoFe alloy and CoxN heterojunction. CoFe-CoxN@NC exhibited an excellent OER activity with the lowest overpotential of 270 mV at 10 mA·cm−2 and stability with the only increment of 20 mV after 80000s in the alkaline media, comparable to that of commercial Ir/C catalyst. The as-prepared catalyst with high activity and cycle stability was attributed to the synergistic effect of CoFe alloy, CoxN and nitrogen-doped encapsulated grapheme lawyer, that reduce the adsorption strength between *O and CoFe alloy, prevent metals leaching and agglomeration, and improve the electron transfer efficiency. This method not only turned waste into treasure from biomass waste lignin, but also provided a solution for the replacement of precious metal catalysts in the field of renewable energy conversion and storage.