Multifunctional silver bromide and graphitic carbon nitride decorated α-MnO₂ nanorods for RhB degradation, water splitting and antibacterial activity

Oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are considered fundamental processes for electrochemical energy conversion and storage in fuel cell, water electrolyzer, and metal-air battery systems. Here, a hydrothermal approach was utilized for the preparation of graphitic carbon nitride (g-C₃N₄) and silver bromide (AgBr) doped manganese dioxide (α-MnO₂) nanorods (NRs) to enhance electrochemical performance, degradation efficiency, and antibacterial potential through novel co-doping strategy. The ternary system contains a fixed quantity of (3 wt %) g-C₃N₄ at different concentrations (1 and 3 wt %) of AgBr in α-MnO₂. Different techniques comprising X-ray diffraction, UV–visible spectroscopy, transmission electron microscopy, linear sweep voltammetry and electrochemical impedance spectroscopy were employed to examine structural, optical, and electrochemical features of undoped and doped α-MnO₂ NRs. The results indicated an improved electrocatalytic performance for (1 wt %) AgBr/g-C₃N₄ doped α-MnO₂, exhibiting a decreased charge transfer resistance and low overpotential value (202) mV for OER. Additionally, a remarkable HER activity was achieved by the same material, showing a lower overpotential of 119 mV to attain a current density of −20 mA cm⁻². Furthermore, the catalytic activity was carried out to check the degradation of rhodamine B dye using pristine and doped α-MnO₂ NRs and maximum degradation potency was observed in basic medium for (1 wt%) AgBr. Efficient antibacterial efficacy was checked using Escherichia coli (E. coli) microbes possessing the highest inhibition area of 8.15 mm upon (3 wt%) AgBr doping. The possible obstructive influence of AgBr/g-C₃N₄ doped α-MnO₂ on the DNA gyrase of E. coli was revealed through silico probes. The optimized sample showed significant performance in water splitting, dye degradation and antimicrobial activity, rendering it as a multifunctional candidate for sustainable energy production, environmental remediation and biological applications.