Trifunctional of Phosphorus-Doped NiCo₂O₄ Nanowire Materials for Asymmetric Supercapacitor, Oxygen Evolution...

Nowadays, transition-metal oxides are regarded as the most potential materials for the supercapacitor and electrocatalyst. However, the poor electrical conductivity and insufficient active sites limited their development in various fields. Herein, we report the method of phosphorous-doped NiCo₂O₄ (named as P-NCO) prepared by the two-step strategy: the NiCo₂O₄ nanostructure is grown on the nickel foams by hydrothermal treatment and subsequently phosphatized in a tube furnace. Successfully, the rich oxygen vacancies and the P element introduced into the NiCo₂O₄ structure obviously improve the electrical conductivity, and the resulting P-NCO NWs/NF material shows an ultrahigh specific capacitance of 2747.8 F g^-1 at 1 A g^-1 and a prominent rate performance (maintain 50% at 100 A g^-1). Furthermore, the assembled P-NCO NWs/NF//RGO asymmetric supercapacitor has an energy density of 28.2 W h kg^-1 even at a high power density of 7750.35 W kg^-1. After 10,000 cycles, the capacitance still also has an 88.48% retention rate. As an electrocatalyst, P-NCO NWs/NF has an excellent hydrogen evolution reaction (55 mV at 10 mA cm^-2) and oxygen evolution reaction (300 mV at 10 mA cm^-2) activities in 1 M KOH solution. This study provides an effective strategy to prepare multifunctional materials.