Surface oxidized iron-nickel nanorods anchoring on graphene architectures for oxygen evolution reaction

Surface oxidized iron-nickel nanorods coupling with reduced graphene architectures(FeNi-O-rGA)are successfully constructed via hydrothermal,freeze-drying,and thermal activation approaches.The hierarchical structure can provide lots of pathways for fast ion diffusion and charge transfer,and expose abundant catalytic sites.Meanwhile,the activity of FeNi-O-rGA is boosted by the optimized metal-oxygen bond strength in FeNi_(3)alloys.Partial oxidized FeNi nanorods are strongly coupled with rGA by the formation of metal-O-C bonds,which can impede the aggregation of FeNi_(3)alloys and increase the utilization of active sites.The special structure and partially oxidized FeNi nanorods for FeNi-O-rGA can result in excellent OER activity and catalytic stability.Only 215 mV of overpotential is required to drive the current density of 10 mA/cm^(2)as well as the Tafel slope of 50.9 mV/dec in 1 mol/L KOH.The change of surface chemistry of FeNi-O-rGA is confirmed by XPS after the OER test,which indicates the highly catalytic stability of FeNi-O-rGA due to the formation of intermediate metal oxyhydroxide.