In situ coupling of lignin‐derived carbon‐encapsulated CoFe‐CoxN heterojunction for oxygen evolution reaction

Abstract Exploring highly active and stable electrocatalysts for oxygen evolution reaction (OER) is crucial for developing water splitting and rechargeable metal‐air batteries. In this study, a hybrid electrocatalyst of CoFe alloy and Co x N heterojunction encapsulated and anchored in N‐doped carbon support (CoFe‐Co x N@NC) was in situ coupled via the pyrolysis of a novel coordination polymer derived from lignin biomacromolecule. CoFe‐Co x N@NC exhibited outstanding OER activity with a low overpotential of 270 mV at 10 mA cm −2 and stability with an increment of 20 mV, comparable to commercial Ir/C. DFT calculations showed that Co x N and N‐doped graphitic encapsulation can reduce the binding strength between *O and CoFe alloy, limit metal leaching and agglomeration, and improve electron transfer efficiency, considerably enhancing the OER activity and stability. In situ coupling approach for preparing alloy and nitride heterojunctions on N‐doped lignin‐derived carbon offers a promising and universal catalyst design for developing renewable energy conversion technologies.