Self-sacrificial growth of hierarchical P(Ni, Co, Fe) for enhanced asymmetric supercapacitors and oxygen evolution reactions

Abstract

Highly efficient and environmentally friendly multifunctional electrode materials for application in supercapacitors to electrocatalysis are important for advances in the future of electrical energy storage and green hydrogen production. This work reports a simple growth strategy to obtain hierarchical P(Ni, Co, Fe) modified electrodes by phosphating a core/shell composite of nickel-cobalt (NiCo) Prussian blue analogues fabricated through an in situ self-sacrificial growth process. Due to the unique microstructure, abundant surface-active sites, and enhanced interfacial conductivity, the hybrid electrode exhibits specific capacitance as high as 1125.8 F g −1 (3.7 F cm−2) at 2 mA cm−2, excellent rate capability and improved cycling stability (97.1% retention capacitance after 5000 cycles at 50 mA cm−2 and 89.9% after continuous 5000 cycles at 100 mA cm−2). Furthermore, the hybrid structure shows excellent oxygen evolution reaction performance with an overpotential of 252 mV at 100 mA cm−2 and 283 mV at 300 mA cm−2, with a low Tafel slope of 68 mV dec−1, and overall water splitting abilities with a cell voltage of 1.55 V at 100 mA cm−2. This work provides insights into the design of next-generation high-performance multifunctional electrode materials by controlling the surface/interface of multicomponent structures for enhancing their properties.