Visible Light Assisted CuO/g-C₃N₄ Nanocomposite Photocatalyst for Dye Degradation and In-Vitro Deactivation of Pseudomonas aeruginosa Bacteria

CuO/g-C₃N₄ nanocomposites were synthesized using one-step ultrasonic dispersion method with different amounts of CuO loadings (1%, 3%, and 5 wt%) onto g-C₃N₄ 2D sheets. Advanced analytical techniques like XRD, XPS, SEM, TEM, and SAED was applied to study structural, elemental, and morphological properties of synthesized materials. Absorption spectroscopy was used to calculate band gaps and found that energy band gaps gradually decreased with the increase in CuO nanoparticles loading onto g-C₃N₄ sheets. We tested our synthesized materials for photocatalysis, and found that 3% CuO/g-C₃N₄ nanocomposite exhibited promising photocatalytic activity against rhodamine blue (RhB) dye (~ 95% degradation) using visible light illumination due to the enhanced absorption spectrum, fast charge carrier separation, and reduced recombination. Additionally, rate constant was found four times higher than the g-C₃N₄. The rate constant followed the order 3% CuO/g-C₃N₄ (k = 0.03941 min⁻¹) > 5% CuO/g-C₃N₄ (k = 0.0184 min⁻¹) > 1% CuO/g-C₃N₄ (k = 0.01252 min⁻¹), and g-C₃N₄ (k = 0.01056 min⁻¹). Furthermore, we studied the antibacterial activity of synthesized nanocomposites against Pseudomonas aeruginosa (Gram-negative) bacteria under visible light. We found that adding 3% CuO/g-C₃N₄ nanocomposites reduced the cell count initially, and the reduction was even more lethal as we increased the visible light exposure time. Reactive oxygen species (ROS) generation in 3% CuO/g-C₃N₄ nanocomposite facilitates oxidative stress and disrupts bacterial cells. It is encouraging to conclude that 3% CuO/g-C₃N₄ nanocomposite has great potential for water treatment and deactivating dangerous pathogens for field applications.