Porous coral-like nickel-cobalt-phosphide composited with graphene nanosheets: A supercapacitive behavior

Abstract

This research introduces the supercapacitive behavior of porous coral-like nickel-cobalt-phosphide composited with reduced graphene nanosheets (RGNs) using a straightforward one-step hydrothermal process. Several surface and electrochemical methods were used to follow the fabrication and study the electrochemical behavior and supercapacitive charge storage performance of the composite (NiCoP/RGNs) and its ancestors (NiP, CoP, NiP/RGNs, and CoP/RGNs). The effects of each component, NiP, Co, and graphene, on the performance of the composite were studied. In the composite with the optimum proportion of ingredients, the presence of NiP contributed to the high specific capacity, Co enhanced the intrinsic conductivity and electrochemical activity, and graphene significantly increased the surface area and electrical conductivity, leading to improved overall performance of the NiCoP/RGNs composite. The NiCoP/RGNs composite exhibited a uniformly shaped porous nanostructure with coral-like morphology and superior specific capacity of 982 C g⁻¹ at 1 A g⁻¹ (2455.6 F g⁻¹), which can be attributed to its substantial specific surface area, notable intrinsic conductivity, and fleeting reversible faradic reaction properties. The asymmetric supercapacitor (ASC), made up of stainless steel modified with NiCoP/RGNs as a positive electrode and industrial active carbon as a negative electrode, revealed a high energy density of 54.63 W h kg⁻¹ at a power density of 749.49 W kg⁻¹ with 81 % capacity retention after 4000 cycles. The research may open up possibilities for the one-step, straightforward production of highly porous bimetallic phosphide materials, combined with graphene nanosheets, to store electrochemical energy.