Enhanced Photocatalytic and Antibacterial Properties of NiO-CoO-Based Ternary Composites: Role of SnO2 and Al2O3 Incorporation

Rapid industrial expansion and discharge of synthetic dyes pose a severe threat to environmental and human health. To address these challenges, transition metal oxides and their composites have been widely investigated as photocatalysts for wastewater treatment. However, their limited visible-light absorption and rapid electron-hole recombination limit their dye degradation efficiency under natural sunlight. In this work, ternary metal oxide composites NiO–CoO–X (X = Al 2 O 3 and SnO 2 ) were synthesized via a simple coprecipitation method to overcome these limitations. The structural, optical, chemical, and morphological properties of the synthesized composites were systematically characterized using XRD, UV–Vis, FTIR, and SEM. The photocatalytic activity was investigated for Methyl Orange (MO) dye degradation under 180 min of sunlight irradiation. Comparatively, the NiO-CoO-Al 2 O 3 composite exhibited the highest photocatalytic degradation efficiency of 88%, which is attributed to the empirically observed enhancement in visible-light absorption and structural microstrain. Furthermore, the composites demonstrated significant antibacterial activity against selected bacterial strains. Our results suggest that NiO–CoO– Al 2 O 3 and NiO–CoO–SnO 2 composites are promising candidates for efficient, cost-effective, and environmentally sustainable photocatalysts for wastewater treatment applications.