LAUSR

Abstract The modification of active sites in electrocatalysts is important for energy conversion and storage systems. Here, CoOx/N-doped graphene/polymeric carbon nitride (CoOx/NG/PCN) hybrid was prepared by thermal annealing method. The introduction of NG greatly prevented the aggregation of CoOx nanoparticles. Further doping PCN into CoOx/NG, CoOx/NG/PCN showed wrinkle and cross-linked structure. And the introduction of PCN can effectively increase the contents of pyridinic N and numbers of O defects to result in the improved oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance. Detailed experiments suggested that the onset and half-wave potentials (Eonset and E1/2) of CoOx/NG positively shifted of 110 and 100 mV, respectively compared to pure CoOx nanoparticles. When further doping PCN into CoOx/NG, Eonset and E1/2 were further positively shifted of 40 and 110 mV, respectively. More importantly, such ORR activity exhibited comparative activity and even more superior stability and excellent methanol tolerance than commercial Pt/C. Additionally, the resulted CoOx/NG/PCN also showed superior OER activity. Compared with CoOx/NG and CoOx, the overpotential of CoOx/NG/PCN for 10 mA/cm2 current densities was decreased for 160 mV and 180 mV, respectively. Especially, the investigation herein may assist in a new insight to bond configurations modification of catalysts and can be extended to other catalytic systems.