<p>This study examines the photocatalytic capabilities of BiFeO₃, g-C₃N₅ nanoparticles, and BiFeO₃/g-C₃N₅ nanocomposite in the degradation of azorubine dye and its use in sensors. The structural, morphological, optical, sensing, impedance, photoluminescence, and photocatalytic properties of the produced perovskite and nanocomposite were examined. Developed BiFeO₃/g-C₃N₅ nanocomposite has a nano staked structure with optimum band gap of 1.67&#xa0;eV that makes it active in visible region by delaying recombination rate compared to g-C₃N₅ (1.54&#xa0;eV) and pure BiFeO₃ (1.97&#xa0;eV). Compared to pure BiFeO₃, the BiFeO₃/g-C₃N₅ nanocomposite has demonstrated greater photocatalytic activity (96.46%) and stability under visible light irradiation. The possible mechanism behind the superior photocatalytic performance of nanocomposite has been critically discussed. The scavenging experiment indicated the major role played by h⁺ to improve photocatalytic activity of synthesized nanocomposite. In essence, this paper pioneers a novel concept for of heterojunction s-scheme photocatalyst with recyclability and photostability that can also sense the lead (Pb²⁺) and the cadmium (Cd²⁺). These structural and electronic features correlate with the observed sensing performance, demonstrating that thermal modulation of g-C₃N₅ enables control over porosity, molecular ordering, and charge transport for effective Pb²⁺ and Cd²⁺ detection.</p> Graphical abstract <p></p>