Effect of different Cu:Co film concentrations on photocatalytic reactions of ethanol, MB, AMX, and Cr(VI): A study of film properties & effects of photooxidation

Abstract

Wastewater treatment is an urgent challenge of the 21st century, and photocatalysis represents a promising approach. However, much of the research has focused on powdered photocatalysts and complex, costly methods, leading to limitations in practical applications. This study introduces an innovative approach to produce Cu:Co thin films with different weight ratios (70:30, 50:50, and 30:70) by the low-cost dip-coating technique. The photocatalytic activity of Cu:Co films was investigated through the photooxidation of alcohol (EtOH), degradation of dye (MB), antibiotic (AMX), and photoreduction of heavy material ions (Cr(VI)) under sunlight irradiation. The results clearly show that higher Cu concentration ratios (70:30%) resulted in smoother surfaces (49.7 nm), higher droplet contact angle (72.43°), smaller particles (67 nm), lower film thickness (365 nm), narrower band gap (1.68 eV), higher transmittance (26.7%), and improved degradation of MB (78% for 4 h) and amoxicillin (43% for 45 min). Conversely, higher Co ratios may yield contrasting effects in most cases. The photoreduction of Cr(VI) showed similar results for Cu:Co films with 70:30 and 50:50 ratios, reaching 42.81% and 43.82% for 30 min, respectively. The effect of the ethanol photooxidation process significantly reduced the roughness, film thickness, and band gap in all Cu:Co films while enhancing transmittance, except for the 50:50 Cu:Co ratio. Cu:Co films are ideal for practical applications such as photoreaction processes due to their efficiency, sustainability, and stability.