Sustainable energy generation: Cu-α-Mno2 coupled with SGCN: A breakthrough in photoelectrocatalysis for overall water splitting

We report a dual-engineered heterostructure based on Cu-doped α-MnO 2 integrated with sulfur-doped graphitic carbon nitride (SGCN) for enhanced photoelectrochemical performance. Controlled Cu doping (1–9 wt.%) was employed to modulate the electronic structure of α-MnO 2 , while SGCN was introduced to construct an efficient heterojunction and improve charge transport. The optimized 7 wt% Cu-α-MnO 2 coupled with 70 wt% SGCN exhibited remarkable bifunctional activity, delivering low overpotentials of 300 mV for OER and 84 mV for HER in 1 M KOH under illumination. Cu-induced electronic modulation and SGCN-mediated interfacial charge separation work in concert to improve light absorption, lower charge transfer resistance, and inhibit electron–hole recombination, which is responsible for the higher performance. Additionally, the composite demonstrated excellent electrochemical stability and enlarged electrochemically active surface area, ensuring long-term durability. This work provides a rational design strategy for MnO 2 -based heterostructured photoelectrocatalysts and advances the development of cost-effective systems for solar-driven hydrogen generation.