Cailiang Yue,Changqing Zhu,Wenting Zheng,Jinli Qiu,Zhiling Du,Chen Ling,Fu-Qiang Liu
Highly efficient mineralization of refractory organic pollutants is an admittedly difficult problem for most photocatalytic processes. Herein, a hierarchical type-II heterojunction Bi2MoO6/Bi/BiOBr-x (BMO/Bi/BOB-x) was successfully fabricated via a one-pot solvothermal method. The optimal BMO/Bi/BOB-2 exhibited an ∼80% mineralization ratio of ciprofloxacin under simulated solar irradiation, outperforming most reported photocatalysts. ˙OH was demonstrated to be the dominant reactive species. The ˙OH production capacity of BMO/Bi/BOB-2 increased by 76.2% compared with that of BMO/BOB, highlighting the key role of Bi nanoparticles (Bi NPs). Bi NPs not only induced a strong localized surface plasmon resonance effect to enhance the utilization of visible light, but also acted as an electron mediator to accelerate the separation of e−/h+ pairs. Due to the specific redox potential, the separated h+ and e− could activate H2O and O2 to produce ˙OH synchronously. Overall, this work provided a valuable strategy to design a plasmonic Bi NP-enhanced type-II heterojunction for the efficient treatment of refractory organic wastewater.
Perfluorooctanoic acid (PFOA) is potentially toxic and exceptionally stable attributed to its robust C F bond, which is hard to be removed by UV/TiO 2 systems. In this research, bismuth nanoparticle (Bi NP) modified titanium oxides (Bi/TiO 2 ) were synthesized by a simple photochemical deposition-calcination method and were applied as photocatalysts for the first time to degrade PFOA. The removal rate of 50 mg/L PFOA reached 99.3 % with 58.6 % defluorination rate after 30 min of irradiation via a mercury lamp. Bi/TiO 2 exhibited superior performance in PFOA degradation compared to commercial photocatalysts (TiO 2 , Ga 2 O 3 , Bi 2 O 3 and In 2 O 3 ). In addition, Bi/TiO 2 showed high degradation activity under actual sunlight, achieved 100 % removal rate and 59.3 % defluorination rate within 2 h. Bi NPs increase the light trapping ability of Bi/TiO 2 and promote the separation of photogenerated electron-hole pairs via local surface plasmon resonance (LSPR) effect, which results in more photogenerated holes (h + ) and hydroxyl radicals ( OH). Combined with DFT calculations and intermediate detections, the degradation reaction is initiated from the oxidation of the PFOA carboxyl group via h + , followed by the loss of the CF 2 unit step by step with the participation of OH. This work presents a novel approach for the practical implementation of TiO 2 -based photocatalysts to achieve highly efficient photocatalytic degradation of perfluorocarboxylic acids (PFCAs).
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