Perfluorooctanoic acid (PFOA) is a new-found hazardous persistent organic pollutant, and it is resistant to decomposition by hydroxyl radical (HO) due to its stable chemical structure and the high electronegativity of fluorine. Photocatalytic reduction of PFOA with β-Ga 2 O 3 in anoxic aqueous solution was investigated for the first time, and the results showed that the photoinduced electron (e − cb ) coming from the β-Ga 2 O 3 conduction band was the major degradation substance for PFOA, and shorter-chain perfluorinated carboxylic acids (PFCAs, C n F 2n+1 COOH, 1 ≤ n ≤ 6) were the dominant products. Furthermore, the concentration of F − was measured by the IC technique and defluorination efficiency was calculated. After 3 hr, the photocatalytic degradation efficiency was 98.8% and defluorination efficiency was 31.6% in the presence of thiosulfate and bubbling N 2 . The degradation reaction followed first-order kinetics ( k = 0.0239 min −1 , t 1/2 = 0.48 hr). PFCAs (C n F 2n+1 COOH, 1 ≤ n ≤ 7) were detected and measured by LC-MS and LC-MS/MS methods. It was deduced that the probable photocatalytic degradation mechanism involves e − cb attacking the carboxyl of C n F 2n + 1 COOH, resulting in decarboxylation and the generation of C n F 2n + 1 . The produced C n F 2n + 1 reacted with H 2 O, forming C n F 2n + 1 OH, then C n F 2n + 1 OH underwent HF loss and hydrolysis to form C n F 2n+1 COOH.
Jin Liu,Wei Lu,Qian Zhong,Hongzhang Wu,Yunlin Li,Lili Li,Zhenling Wang
Semiconductor photocatalysis has become the focus of recent research on antibiotic treatment because it is a green and efficient technology. In this study, α-GaOOH with several novel microstructures has been synthesized at a low temperature and its subsequent thermal transformation. The influence of pH on the synthesis of α-GaOOH is studied, and the results indicate that pH played an important role in the microstructures of α-GaOOH and β-Ga 2 O 3 . All Ga 2 O 3 samples possess macro-mesoporous network structures and exhibits a remarkable photocatalytic activity for antibiotic degradation. The photoelectron chemical tests show that the separation efficiency of photogenerated charge carriers of Ga 2 O 3 -7.0 is higher than that of other Ga 2 O 3 . The enhanced photocatalytic activity of Ga 2 O 3 -7.0 is mainly ascribed to its morphology and oxygen vacancy . The active species trapping and photoluminescence measurement experiments indicate that OH and O 2 − are the major active species contributing to the photocatalytic process. This study will bring about the potential application in treatment of the antibiotic pollutants.
Ga 2 O 3 is considered as a candidate for the preparation of solar-blind photodetectors due to its large direct band gap. Developing low-cost preparation methods of high-quality Ga 2 O 3 films is of importance for large-scale applications. In this work, we investigate the preparation of Sn doped β-Ga 2 O 3 films by using simple and cheap sol–gel method under ambient condition. It is found that Sn doping induces a growth mode transformation from \(\left( {\overline{2}01} \right)\) to \(\left( {\overline{3}11} \right)\) oriented texture on the c-plane sapphire substrates. With an optimal Sn proportion, high-quality β-Ga 2 O 3 films consisting of needle-like grains are observed. Compared with the undoped films, the Sn-doped films with needle-like grains obtained a low dark current of 0.76 nA, performed an on/off ratio as high as ~ 6000, responsivity, R of 164 mA/W and D* of 3.21 × 10 12 Jones at a bias voltage of 30 V in the configuration of metal–semiconductor–metal solar-blind deep ultraviolet detectors. This is the highest on/off ratio of Ga 2 O 3 solar-blind photodetectors fabricated by sol–gel method reported up to now and has the potential to be applied in practical use. Graphical abstract
危险品化学品经营许可证（带存储）