Anionic bimetallic strategy and g-C₃N₄ Supported CeSe₂-Cu₂O/g-C₃N₄ heterostructure for stable and efficient overall water electrolysis

Hydrogen is a promising clean, renewable energy source with zero carbon waste, generated via an electrochemical conversion system. The key to electrocatalytic water splitting lies in the semi-reactions, such as OER/HER, and overall water splitting, yet remains hindered by their sluggish kinetics. To overcome this challenge, the development of an appropriate, competent, low-cost, and efficient bifunctional electrocatalyst for hydrogen and oxygen evolution is highly desirable. In this perspective, we adopted a hydrothermal method to design an efficient CeSe₂-Cu₂O/g-C₃N₄ heterostructure as a bifunctional electrocatalyst. The layered structure of roughly spherical nanoparticles and the higher redox potentials of Ce³⁺/Ce⁴⁺ and Cu¹⁺/Cu²⁺ on the catalyst surface created heterojunction interfaces for active centres and strong electronic interactions for robust charge-transport rates, which accelerate the OER and HER activity with impressive electro-catalytic potential of 202 and 89 mV at standard current density by using 1.0 mol alkaline electrolyte. Besides, the anionic edge sites in the structure of CeSe₂-Cu₂O/g-C₃N₄ optimised the adsorption of reactants and intermediates, thereby demonstrating superior stability of 60 h and 80 h for OER and HER, respectively. In the overall water electrolysis test, the CeSe₂-Cu₂O/g-C₃N₄ electrolyser exhibits excellent stability for 40 h at 1.53 V, maintaining 10 mA cm⁻². The present work proposes a new approach to designing an efficient and stable bifunctional catalyst to enhance electrocatalytic water splitting performance by coupling g-C₃N₄ via an anionic bimetallic strategy.