Sunlight-Driven Synthesis of TiO2/(MA)2SnCl4 Nanocomposite Films for Enhanced Photocatalytic Degradation of Organic Pollutants

Abstract

In this study, a TiO2/(MA)2SnCl4 nanocomposite film was synthesized using a sustainable, sunlight-driven approach, demonstrating enhanced photocatalytic performance for environmental remediation. TiO2 nanoparticles (TiO2-NPs) were dispersed in ethanol and mixed with a methylammonium (MA) and SnCl2 precursor solution, followed by drop-casting onto a glass substrate and exposure to direct sunlight for 2 h. Sunlight served as an energy source, facilitating in situ structural modifications and leading to the formation of a well-integrated TiO2/(MA)2SnCl4 hybrid structure, where TiO2 was effectively encapsulated. Characterization revealed a band gap reduction from 3.1 eV (TiO2-NPs) to 2.6 eV in the nanocomposite, extending light absorption into the visible range. The formation of Sn–O–Ti interactions enhanced charge separation, minimized electron–hole recombination, and improved charge carrier dynamics. Photocatalytic degradation tests using methylene blue (MB) under sunlight showed that the nanocomposite film achieved 90% MB degradation within 60 min, outperforming TiO2-NPs, which achieved only 75% degradation. The presence of oxygen vacancies (OVs) generated during sunlight exposure further enhanced photocatalytic efficiency by acting as charge traps and reaction sites. This study introduces a green synthesis strategy leveraging sunlight as a renewable energy source, marking the first integration of (MA)2SnCl4 with TiO2-NPs for enhanced photocatalysis. The synergistic effects of extended visible-light absorption, defect engineering, and efficient charge separation make TiO2/(MA)2SnCl4 nanocomposite films a scalable, cost-effective solution for water purification applications, offering a promising solar-driven approach to addressing global water contamination challenges.