Facile preparation of Z-scheme based graphene/TiO2/MnO2 hybrid nanomaterial: A dual application in hazardous dye and antibacterial reduction

This study explores the photocatalytic degradation efficacy of methylene blue (MB) dye, a prevalent water pollutant, employing graphene/TiO₂/MnO₂ (GTM) hybrid photocatalyst. The photocatalytic degradation performance against MB dye revealed that the as-prepared GTM hybrid photocatalyst exhibited superior activity, achieving a degradation efficiency of 97 % within 40 min of UV–visible light irradiation. Notably, the GTM hybrid photocatalyst demonstrated a high-rate constant (k) of 0.174 min⁻¹ , surpassing that of the bare TiO₂ (k = 0.030 min⁻¹) and MnO₂ (k = 0.047 min⁻¹) photocatalysts. Cyclic stability tests up to ten cycles confirmed the excellent durability of the GTM hybrid photocatalyst, retaining 80 % of its initial activity. Hydroxyl and superoxide radicals play a significant role in the degradation process, while the heterojunction structure significantly enhances charge separation, further improving photocatalytic efficiency. The enhanced photocatalytic performance of the GTM hybrid can be attributed to the improved charge carrier separation, augmented surface area, and 2D/2D/1D heterojunction formation. Also, the antibacterial activity of the as-prepared photocatalyst was analyzed over Klebsiella pneumoniae (KP) and Staphylococcus aureus (SA) using the agar well diffusion method. The observed results show that the GTM has effective antibacterial activity against both microorganisms. This research contributes to developing sustainable materials and processes for environmental remediation, aligning with the principles of green chemistry and promoting a cleaner, healthier environment.