Fabrication of type II ZrO2/heteropoly blue heterojunction photocatalysts for efficient organic dye degradation

ZrO₂-(NH₄)₃PW₁₂O₄₀ composites (ZW-X) were successfully prepared after annealing at temperatures ranging from 250 °C to 450 °C for the degradation of organic dyes. A thorough investigation was conducted to evaluate the impact of calcination temperature on the structural configuration, morphological properties, bandgap energetics, and charge transfer behaviors of the ZW composites. The results revealed that ZW-350 achieved an optimal structural configuration through the formation of heteropoly blue (HPB) after calcination at 350 °C for 2 h. Notably, the ZW-350 photocatalyst exhibited exceptional photocatalytic activity towards rhodamine B (RhB) and methylene blue (MB) under both ultraviolet and simulated solar irradiation. Furthermore, RhB could be efficiently photodegraded in various water bodies using ZW-350. These remarkable performances can be attributed to the formation of a type-II heterojunction between ZrO₂ and HPB within the ZW-350 composites. During the photodegradation process of RhB, hydroxyl radicals (˙OH), superoxide radicals (˙O₂⁻), and photo-generated holes (h⁺) were identified as the primary active species. This study presents a novel method for the preparation of advanced HPB-based materials for the degradation of organic pollutants.