Photo-induced Production of Chlorine Molecules from Titanium Dioxide Surfaces Containing Chloride
Photo-induced Production of Chlorine Molecules from Titanium Dioxide Surfaces Containing Chloride
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含氯二氧化钛表面光诱导产生氯分子
DOI：
10.1021/acs.estlett.9b00704
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发表时间：
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影响因子：
10.9
通讯作者：
Ding Aijun
中科院分区：
文献类型：
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作者：
Li Yuanyuan;Nie Wei;Liu Yuliang;Huang D;an;Xu Zheng;Peng Xiang;George Christian;Yan Chao;Tham Jun Yee;Yu Chuan;Xia Men;Fu Xiao;Wang Xinfeng;Xue Likun;Wang Zhe;Xu Zhengning;Chi Xuguang;Wang Tao;Ding Aijun
二氧化钛在城市化进程中被广泛使用，并可能影响大气化学，但目前尚不清楚。在这项工作中，我们展示了光照下KCl涂层的二氧化钛薄膜产生了大量的Cl2，并提出了一个重要的白天氯自由基的来源。我们发现，反应需要水和氧气才能进行，Cl2的生成量随着包覆量、载气湿度和光照强度的增加而线性增加。这些结果表明，水通过与晶格相互作用释放游离氯离子(Cl-)来促进包覆KCl的反应性。自由的Cl-通过光活化的TiO2转移电荷到O2上，形成Cl2，可能还有O2-自由基。除Cl2外，通过Cl2/Cl2与HOx的络合反应还可观察到ClO和HOCl2。在上海进行了一次密集的活动，在此期间观察到了明显的日间Cl2峰值。当含有二氧化钛的表面达到城市表面的20%时，二氧化钛光催化产生的Cl2估计可达0.2 ppb/h，并且与观测到的Cl2高度相关。我们的结果表明，二氧化钛通过改变自由基预算在大气光化学中起着不可忽视的作用。
Titanium dioxide (TiO2) is extensively used with the process of urbanization and potentially influences atmospheric chemistry, which is yet unclear. In this work, we demonstrated strong production of Cl2from illuminated KCl-coated TiO2membranes and suggested an important daytime source of chlorine radicals. We found that water and oxygen were required for the reactions to proceed, and Cl2production increased linearly with the amount of coated KCl, humidity of the carrier gas, and light intensity. These results suggested that water promotes the reactivity of coated KCl via interaction with the crystal lattice to release free chloride ions (Cl–). The free Cl–transfer charges to O2via photoactivated TiO2to form Cl2and probably the O2–radical. In addition to Cl2, ClO and HOCl were also observed via the complex reactions between Cl/Cl2and HOx. An intensive campaign was conducted in Shanghai, during which evident daytime peaks of Cl2were observed. Estimated Cl2production from TiO2photocatalysis can be up to 0.2 ppb/h when the TiO2-containing surface reaches 20% of the urban surface, and highly correlated to the observed Cl2. Our results suggest a non-negligible role of TiO2in atmospheric photochemistry via altering the radical budget.