Enhanced photocatalytic activity of Sn3O4/TiO2 heterostructures for Cr(Ⅵ) reduction and isoniazid degradation

Abstract

The utilization of photocatalytic technology to degrade contaminants such as heavy metals and antibiotics holds immense significance. Nevertheless, the pursuit of highly efficient photocatalysts remains a formidable challenge. Herein, a series of Sn₃O₄/TiO₂ (ST) hybrid photocatalysts composed of TiO₂ nanoparticles (NPs) and Sn₃O₄ nanosheets (NSs) have been designed and constructed to enhance the reduction of Cr(VI) and the degradation of ISN. TiO₂ NPs were loaded onto the 2D layered flowerlike Sn₃O₄ NSs uniformly through a solvothermal approach, resulting in unique three-dimensional (3D) heterostructures. As expected, all ST composites exhibit higher degradation activity compared to pristine Sn₃O₄ and TiO₂. The optimal ST-0.6 composite (with a TTIP amount of 0.6 g) possesses the highest degradation rate, achieving a 99.6 % removal for Cr(Ⅵ) within 60 min under Xenon light irradiation, with a rate constant (k) of 0.091 min⁻¹. This performance surpasses that of pristine Sn₃O₄ and TiO₂, which have rate constants of 0.0199 min⁻¹ and 0.0186 min⁻¹. Additionally, the ST-0.6 composite effectively removes 72.8 % for isoniazid (ISN) within 80 min. It exhibits the highest photodegradation rate of 0.014 min⁻¹, being 1.3 and 140 times higher than that of TiO₂ (0.0107 min⁻¹) and Sn₃O₄ (0.0001 min⁻¹), respectively. Furthermore, the photocatalytic degradation activities of the recovered samples retain their photocatalytic degradation performance after three consecutive experimental cycles, indicating relatively excellent durability. According to the photocatalytic and characterization results, the significantly enhanced photoactivity of the ST hybrid photocatalyst is attributed to the increased reaction sites, improved light-harvesting properties, and enhanced separation and transfer efficiency of photogenerated electrons and holes within the ST heterostructures.