CVD-grown NiO-carbon nanofiber decorated rGO hybrids for high-performance electrochemical hydrogen storage: role of hierarchical porous structures

Abstract

The development of sustainable materials for green energy storage systems has accelerated due to the growing demand for energy worldwide and environmental concerns. Because of their large surface area, electrical conductivity, and adjustable structure, mesoporous graphitic carbon-based materials show the most promise for electrochemical hydrogen storage (EHS). The electrochemical performance of these materials is further improved by integrating them with transition metal oxides. In this work, chemical vapor deposition was used to create hierarchically organized reduced graphene oxide/NiO-carbon nanofiber (rGO/NiO-CNF) hybrid materials with different ratios of rGO to NiO-CNF. In order to ascertain discharge capacity and the impact of composition on charge storage, cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques were used to examine their systematic electrochemical behaviour. The kinetic or diffusion-controlled charge contributions of the electrocatalysts for EHS are examined. The successful decorating of rGO with NiO-CNFs was validated by structural and elemental studies, which revealed a porous, networked architecture that is conducive to charge accumulation and ion transport. The 1 : 1 rGO/NiO-CNF hybrid electrocatalyst showed the highest specific capacitance of 597.2 F g⁻¹ and the best cycling stability over 500 cycles out of all the evaluated electrocatalysts. These findings establish rGO/NiO-CNF hybrids as potential materials for next-generation EHS systems by highlighting the crucial role that the NiO-CNF content plays in improving hydrogen storage performance.