Photo-deposition of AgO thin films on TiO2 substrate for (P-N) hetero-junction applications: Considering the degree of contamination

Abstract

This study explored the development of photocatalytic heterostructures via the P-N junction formation between TiO₂ and AgO. TiO₂ thin films were fabricated on glass substrates through dip coating. Subsequently, photodeposition of AgO was achieved under sunlight irradiation using varying AgNO₃ concentrations (0.5-2.5 g/L). The films were characterized using XRD, SEM, EDX, UV-vis, and water droplet tests. Samples with concentrations below 2 g/L uniquely exhibited the anatase phase, while a significant prominence of AgO was observed in the film prepared with a 2 g/L AgNO₃ concentration. Silver nitrate contamination loads had a significant impact on the particle size and the overall morphological characteristics of the heterojunctions. The band gap values were 3.52 eV for the anatase substrate, whereas the band gaps of the photodeposited films decreased from 2.44 to 1.98 eV. Despite all films being hydrophilic, a rise in water droplet contact angle was observed in the heterojunctions compared to the pure TiO₂. Photodegradation of methylene blue under sunlight irradiation demonstrated exceptional efficiency (>90%) for the 2 g/L AgNO₃ heterojunction in 6 hours, maintaining high photocatalytic activity over multiple cycles (>77%). This same configuration achieved a 50% degradation of amoxicillin within 2 hours. This investigation addresses water contamination issues while offering a straightforward production method for efficient P-N junction co-catalysts.