Modification of Crystal-Optimized TiO<sub>2</sub> with Biomass-Derived Carbon Quantum Dots for Highly Efficient Degradation of Favipiravir in Water
Shuo Chen, Shu-Zhe Zhang, Hong Jiang
Abstract
TiO 2 has been extensively used in the photocatalytic degradation of diverse organic pollutants; however, the wide band gap and high recombination of photogenerated electrons and holes severely limit its practical application. Herein, we propose a novel and cost-effective approach for synthesizing a highly efficient TiO 2 -based photocatalyst by modifying crystalline phase-optimized TiO 2 (with a rutile ratio of 78.5%) with blue algae-derived carbon quantum dots (B-CQDs). The as-synthesized photocatalyst (BCQD@TiO 2–700 ) can activate peroxymonosulfate to degrade 98.6% of the COVID-19 drug favipiravir within 60 min ( k = 0.0438 min –1 ), which was approximately 10 times that of B-CQD-modified TiO 2 and 16 times that of conventional organic-derived CQD-modified TiO 2–700 . The abundant functional groups (−OH, C═O, C–O–C, P–O, etc.) and narrow average particle size (only 1.42 nm) of the B-CQDs, as well as the optimized rutile ratio, are the main reasons for the improved reactivity of BCQD@TiO 2–700 . The nonradical degradation process with 1 O 2 as the main active species dominates favipiravir degradation, which includes the removal of substituents (–F/–NH 2 ) and the opening of a nitrogen heterocyclic ring; these findings are also supported by density functional theory quantum chemical calculations. This work presents a cost-effective TiO 2 -based photocatalyst for the high-efficiency degradation of emerging organic pollutants.