Enhanced photocatalytic degradation of organic pollutants using Zn-Doped TiO2 nanoparticles synthesized via a novel hydrothermal method

Abstract

Transition metal doping, including Zn, is a promising method among various doping strategies employed to enhance TiO2 photocatalysts. However, several challenges such as non-uniform distribution of Zn ions, particle agglomeration, poor stability still exist. To address these limitations, this study presents the development of Zn-doped TiO2 (Zn-TiO2) nanoparticles via a novel hydrothermal synthesis method utilizing oxalic acid (OA) as a hydrolysis inhibitor and also a capping agent. This innovative approach ensures uniform Zn doping and formation of a unique nano-flower-like morphology, significantly enhancing the photocatalytic properties. The Zn-TiO2 catalysts demonstrated remarkable photodegradation efficiency, under simulated light at 100 mW/cm2 , methyl orange achieved complete degradation within thirty minutes. This improved performance is due to the significantly increased surface area, enhancing the retention of photogenerated charge carriers by minimizing their recombination rate, while also broadening the spectral range of light absorption to encompass the visible spectrum. Furthermore, the catalysts exhibit excellent stability and recyclability, maintaining high activity over multiple cycles. Mechanistic investigations indicate that superoxide radicals (O2-) and holes (h+) are essential in boosting photocatalytic activity. The results offer important insights for the design of advanced photocatalysts and underscore the importance of doping strategies in enhancing the functional properties of TiO2 for practical applications in environmental technology.