MOF-derived tunable anatase-rutile TiO2 heterojunctions for high-performance photocatalytic nitrate reduction

Nitrate photocatalytic reduction holds significant promise for wastewater treatment and green synthesis. In this study, the experimental results showed that the TiO 2 -500 sample, composed primarily of anatase phase with rutile phase heterojunctions, demonstrated superior catalytic performance. Under simulated sunlight, the nitrate reduction rate of this sample reaches 501.74 μmol g cat −1 h −1 within 1h, and the nitrate reduction conversion rate was 91.28 %. Notably, the selectivity of NH 4 + and N 2 was 65.12 % and 32.77 %, respectively, yielding a combined selectivity of 97.89 %. Catalytic activity was found to decrease with increasing rutile phase content. The enhanced performance of the anatase-rutile heterojunction stems from two synergistic mechanisms. First, defect states at the interface act as electron-trapping centers, effectively suppressing photogenerated carrier recombination. Second, the catalyst's retained porous MOF-derived structure provides a high contact area with reactants, thereby accelerating reaction kinetics. Through experimental characterization and theoretical calculations, this work elucidates the charge separation dynamics at the heterojunction interface and the nitrate reduction pathway, offering a strategic approach for designing high-efficiency heterojunction photocatalysts.