Optimization of Spray-Pyrolyzed Cu2ZnSnS4 Thin Films Through Gamma Irradiation and Box–Behnken Design to Enhance Photocatalytic Degradation Efficiency

An integrated methodology was employed, incorporating spray pyrolysis synthesis, gamma irradiation post-treatment, and Box–Behnken statistical optimization. This approach was designed to systematically refine the structural and optical properties of CZTS thin films, with the objective of enhancing their photocatalytic degradation efficiency. At a dose of 5 kGy, gamma irradiation resulted in an approximately 300% increase in crystallite size and improved crystallinity relative to non-irradiated samples. As the irradiation increases, the films exhibited a stronger preferential orientation along the (112) plane, which peaked at 20 kGy. Analysis using the Williamson–Hall method revealed complex microstructural evolution, showing crystallite sizes varying from ~12.48 nm to ~71.27 nm based on the irradiation dose applied. The photocatalytic activity was assessed through the UV-driven degradation of Brun Sella Solid dye, employing H2O2 as a co-reactant. The optimization process, guided by the Box–Behnken design which tested parameters such as pH (2 to 14), gamma dose (0 to 20 kGy), and H2O2 volume (100 to 500 μL), achieved a remarkable maximum degradation efficiency of 98% under optimal conditions. This study highlights the synergistic combination of controlled defect engineering through gamma irradiation and meticulous parameter optimization establishing a robust framework for the development of high-performance, earth-abundant photocatalysts suitable for environmental remediation applications.