Nanoarchitectonics of Carbon Nitride/NiO/Zn₃N₂ Heterointerfaces for bifunctional applications in Electrocatalytic water splitting and Coin cell Supercapacitors

The advancement of effective and unswerving electrocatalysts for water splitting and high-performance supercapacitors is essential for sustainable energy conversion and storage. Integrating transition metal heteroatoms can be a pivotal technique to fabricate nanostructures for such bifunctional applications. In this regard, we report graphitic carbon nitride/NiO/Zn3N2 heterointerfaces through a single-step pyrolysis method for oxygen evolution reaction (OER) and Coin cell supercapacitor devices. The synergetic interaction between NiO and Zn₃N₂ advances charge transfer kinetics and augments the electronic structure, while g-C₃N₄ provides a conductive network and additional active sites. Optimized sample NZN400 showed exceptional OER performance with a low overpotential value of 350 mV at 50 mA/cm2, besides a low Tafel slope and high turnover frequency value. In addition, NZN400 electrodes showed a high specific capacitance value of 124 mF/cm2 at 2 mA/cm2 for the half-cell and 19.92 mF/cm2 at 0.2 mA/cm2 for the coin cell device. Fabricated device exhibited excellent cycling stability over 10,000 GCD cycles with a capacitance retention of 95.7 % and columbic efficiency of 99.4 % at 0.4 mA/cm2 and was able to power up several commercial LEDs, a digital hygrometer, and a digital stopwatch for prolonged durations. The results highlight an effective approach for integrating transition metal oxides/nitrides-based compounds with carbon-based materials, aimed at developing economical and high-performance nanostructured materials for electrochemical energy applications.