Interface engineering combined with nitrogen and phosphorus co-doped synergistic optimization strategies for designing hollow/porous N, P-CoWO4@Co3O4 heterojunction nanocubes for superior-performance supercapacitor and oxygen evolution reaction

Co3O4 possesses high activity and desirable capacitance, which is widely applied in the field of oxygen evolution reaction (OER) and supercapacitor (SCs). Nevertheless, the serious challenges of limited active sites and poor electrical conductivity still hinder its commercial application. Herein, the hollow/porous N, P co-doped nanocubes with heterogeneous structure (denoted as N, P-CoWO4@Co3O4 HNCs) are prepared by in situ ion-exchange and co-doping strategies. The heterogeneous structure could change electron density and facilitate electron transfer. Meanwhile, N, P co-doping could enhance the metallicity significantly. Furthermore, the hollow/porous structure could furnish more electrochemical active sites and accelerate the adsorption and desorption between active sites and charged particles. Based on these advantages, N, P-CoWO4@Co3O4 HNCs demonstrates an overpotential of 553.0 mV at 50 mA cm−2 for OER. On the other hand, N, P-CoWO4@Co3O4 HNCs exhibits outstanding specific capacitance (558.0 F g−1 at 0.5 A g−1) and cycling stability. Moreover, N, P-CoWO4@Co3O4 HNCs//AC delivers an ideal energy density (11.4 Wh kg−1 at 473.9 W kg−1), which surpasses most of the Co3O4-based materials. In general, this work furnishes a facile and pioneering strategy for designing the dual-functional electrode materials in the fields of supercapacitor and oxygen evolution reaction.