N-Bi_2O_2CO_3/CdSe量子点光催化氧化NO及原位红外光谱研究

NO Photo-oxidation and In-situ DRIFTS Studies on N-doped Bi_2O_2CO_3/CdSe Quantum Dot Composite

本实验成功制备了氮掺杂碳酸氧铋(N-Bi_2O_2CO_3,N-BOC)/硒化镉量子点(CdSeQDs)复合光催化剂,并将其运用于光催化降解室内空气污染物一氧化氮(NO)。X射线衍射、透射电子显微镜和光电子能谱测试结果表明N-BOC光催化剂在保持原有纳米片结构和形貌的基础上成功负载了CdSeQDs。光催化氧化NO实验结果显示CdSeQDs的引入可显著提高N-BOC的NO去除率,并且二次毒副产物NO2生成率大幅度降低至1%,表明复合光催化剂具有极强的毒副产物抑制特性。固体紫外漫反射吸收光谱和发光光谱测试表明CdSe QDs拓宽并提升了N-BOC的光响应范围和能力,并有效抑制了光生电子-空穴的复合效率。通过原位漫反射傅里叶变换红外光谱技术(DRIFTS)分析,发现在N-BOC/CdSe QDs光催化氧化NO反应过程中没有NO2信号产生,仅观测到NO3-相关信号。机理分析表明超氧自由基(O2-)和光生空穴(h+)是体系中可能存在的活性物种,实现了对NO到NO3-的彻底氧化。

Photocatalyst of N-doped Bi2O2CO3 (N-BOC)/CdSe quantun dots (QDs) composite was sucessfully prepared for degradation of nitric oxide (NO), an indoor air pollutant. The results of X-ray diffraction, transmisssion electron microscopy and X-ray photoelectron spectroscopy showed that after combination with CdSe QDs structure and morphology of N-BOC remained the same as before combination. Photocatalytic degradation of NO showed that introduction of CdSe QDs significantly enhanced the removal ratio of NO. Moreover, the generating ratio of toxic byproduct NO2 decreased to 1%, which indicated efficient inhibition for the toxic byproduct generation. From UV-Vis absorption spectroscopy and photoluminescence spectroscopy, the CdSe QDs showed promotion on light absorption, and inhibition of charged recombination of photo-induced carriers. More importantly, only signals of NO3^- were captured in in situ DRIFTS measurements, whilst the signals from NO2 could be barely detected during photocatalytic process. Superoxide radicals (O2^-) and holes (h^+) are considered to be possible active species in the reaction, which dominate the oxidation process from NO to NO3^-.