NiO nanolayer electrodeposited with Cobalt and Phosphide as a novel supercapacitor with high areal capacitance

In the present work, a novel supercapacitor electrode is fabricated via a two-step synthesis procedure. A NiO nanolayer was initially fabricated on a nickel foam electrode using hydrothermal synthesis to obtain a substrate with a high electrocatalytic area and good adhesive properties. Subsequently, the NiO-decorated nickel foam (NF) was employed as a substrate for the electrodeposition of cobalt and phosphorous. Morphological, structural, and surface characterization, along with various electrochemical tests, were conducted to gain insight into structure-property relationships. The as-prepared electrode (CoP@NF) exhibited excellent electrochemical behavior with an ultra-high areal capacitance of 3340 mF cm⁻² at 5 mA cm⁻² and high capacitance values even at high current densities. The exceptional electrochemical behavior can be attributed to the morphological and electronic modifications induced by aliovalent doping and the synergetic effect between the different electrode counterparts.