N-Doped Carbon Modified (Ni_xFe_1-x)Se Supported on Vertical Graphene toward Efficient and Stable OER Performance

NiFe-based nanomaterials are extensively studied as one of the promising candidates for the oxygen evolution reaction (OER). However, their practical application is still largely impeded by the unsatisfied activity and poor durability caused by the severe leaching of active species. Herein, a rapid and facile combustion method is developed to synthesize the vertical graphene (VG) supported N-doped carbon modified (Ni_xFe_1-x)Se composites (NC@(Ni_xFe_1-x)Se/VG). The interconnected heterostructure of obtained materials plays a vital role in boosting the catalytic performance, offering rich active sites and convenient pathways for rapid electron and ion transport. The incorporation of Se into NiFe facilitates the formation of active species via in situ surface reconstruction. According to density functional theory (DFT) calculations, the in situ formation of a Ni_0.75Fe_0.25Se/Ni_0.75Fe_0.25OOH layer significantly enhances the catalytic activity of NC@(Ni_xFe_1-x)Se/VG. Furthermore, the surface-adsorbed selenoxide species contribute to the stabilization of the catalytic active phase and increase the overall stability. The obtained NC@(Ni_xFe_1-x)Se/VG exhibits a low overpotential of 220 mV at 20 mA cm^-2 and long-term stability over 300 h. This work offers a novel perspective on the design and fabrication of OER electrocatalysts with high activity and stability.