Mixed-Dimensional and Multifunctional NiSiO2/rGO/g-C3N4 Hybrid Electrode for Asymmetric Supercapacitors and Efficient Hydrogen Evolution

초록

The design of multifunctional, low-cost electrode materials using earth-abundant elements is vital for advancing clean energy technologies. In this work, a novel electrode material (NiSiO2/rGO/g-C3N4) was synthesized and thoroughly assessed for its electrochemical energy storage and hydrogen evolution performance. Nickel silicate (NiSiO2) was fabricated via a hydrothermal route. Reduced graphene oxide (rGO) was synthesized using the Hummers method, while graphitic carbon nitride (g-C3N4) was obtained through thermal polymerization of melamine and urea. The components were physically integrated to form a composite with a porous nanoscale architecture and strong interfacial connectivity. Morphological and structural analyses confirmed the successful formation of a well-dispersed hybrid material. Electrochemical studies in a three-electrode setup revealed that the composite (NiSiO2/rGO/g-C3N4) achieved a high specific capacity (Qs) of 1543.5 C g-1 and a specific capacitance (Cs) of 2132.3 F g-1 at 3 mVs-1. The assembled supercapattery, through a two-electrode assembly, delivered a notable energy density (Ed) of 75.6 Wh/kg and a power density (Pd) of 1771.9 W/kg, with capacitance retention of 86.9% after 10,000 continuous cycles, indicating excellent long-term stability. Furthermore, the material showed outstanding electrocatalytic activity toward the hydrogen evolution reaction (HER). It exhibited an overpotential of only 59 mV at 9 mA/cm2 and a favorable Tafel slope of 82.1 mV/dec. These results confirm the potential of NiSiO2/rGO/g-C3N4 as an efficient, scalable, and multifunctional material capable of supporting both advanced energy storage and hydrogen generation applications.

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