Division of Environmental Science and Engineering , Pohang University of Science and Technology (POSTECH) , Pohang 37673 , Korea.
Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control , Guangdong University of Technology , Guangzhou 510006 , China.
Environ Sci Technol. 2019 Aug 20;53(16):9926-9936. doi: 10.1021/acs.est.9b02401. Epub 2019 Aug 1.
Reactive chlorine species (RCS) such as HOCl and chlorine radical species is a strong oxidant and has been widely used for water disinfection. This study investigated a photoelectrochemical (PEC) method of RCS production from ubiquitous chloride ions using a WO film electrode and visible light. The degradation of organic substrates coupled with H evolution using a WO electrode was compared among electrochemical (EC), photocatalytic (PC), and PEC conditions (potential bias: +0.5 V vs Ag/AgCl; λ > 420 nm). The degradation of 4-chlorophenol, bisphenol A, acetaminophen, carbamazepine, humic acid, and fulvic acid and the inactivation of were remarkably enhanced by in situ RCS generated in PEC conditions, whereas the activities of the PC and EC processes were negligible. The activities of the WO film were limited by rapid charge recombination in the PC condition, and the potential bias of +0.5 V did not induce any significant reactions in the EC condition. The PEC activities of WO were limited in the absence of Cl but significantly enhanced in the presence of Cl, which confirmed the essential role of RCS in this PEC system. The PEC mineralization of organic compounds was also markedly enhanced in the presence of Cl where dark chemical chlorination by NaOCl addition induced a negligible mineralization. The H generation was observed only at the PEC condition and was negligible at PC and EC conditions. On the other hand, the oxidation of chloride on a WO photoanode produced chlorate (ClO) as a toxic byproduct under UV irradiation, but the visible light-irradiated PEC system generated no chlorate.
活性氯物种（RCS），如 HOCl 和氯自由基物种，是一种强氧化剂，已广泛用于水消毒。本研究使用 WO 薄膜电极和可见光，研究了一种从普遍存在的氯离子中产生 RCS 的光电化学（PEC）方法。比较了电化学（EC）、光催化（PC）和 PEC 条件（电位偏置：+0.5 V 对 Ag/AgCl；λ>420nm）下使用 WO 电极降解有机底物和析氢的情况。在 PEC 条件下原位生成的 RCS 可显著增强 4-氯苯酚、双酚 A、对乙酰氨基酚、卡马西平、腐殖酸和富里酸的降解以及 的失活，而 PC 和 EC 过程的活性可以忽略不计。WO 薄膜的活性受到 PC 条件下快速电荷复合的限制，+0.5V 的电位偏置在 EC 条件下不会引起任何明显的反应。在不存在 Cl 的情况下，WO 的 PEC 活性受到限制，但在存在 Cl 的情况下，WO 的 PEC 活性显著增强，这证实了 RCS 在该 PEC 系统中的重要作用。在 Cl 的存在下，有机化合物的 PEC 矿化也得到了显著增强，而添加 NaOCl 进行暗化学氯化则导致矿化作用可忽略不计。只有在 PEC 条件下观察到 H 生成，而在 PC 和 EC 条件下则可忽略不计。另一方面，在 UV 照射下，WO 光阳极上的氯氧化产生了作为有毒副产物的氯酸盐（ClO），但可见光辐照的 PEC 系统未产生氯酸盐。
