ZIF-8/g-C_(3)N_(4)复合材料光催化深度氧化NO性能的研究

Photocatalytic performance of ZIF-8/g-C_(3)N_(4) composite for deep oxidation of NO

采用热聚合法和原位沉积法分别制备g-C_(3)N_(4)、ZIF-8及不同质量比的ZIF-8/g-C_(3)N_(4)复合光催化材料,通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)等表征手段对其结构性质进行表征。表征结果表明,合成的ZIF-8/g-C_(3)N_(4)复合材料没有破坏ZIF-8与g-C_(3)N_(4)原始的晶体结构与形貌,且ZIF-8与g-C_(3)N_(4)形成了异质结,ZIF-8/g-C_(3)N_(4)复合材料的BET比表面积比g-C_(3)N_(4)提高了30多倍。光催化氧化去除NO结果表明,12.5%-ZIF-8/g-C_(3)N_(4)的NO氧化去除效率最佳,且不生成有毒中间产物NO_(2),具有最优异的光催化活性,对于NO的氧化去除率可达55.1%。机理研究表明,基于g-C_(3)N_(4)的异质结构不仅抑制了光生载流子的复合,而且由于g-C_(3)N_(4)与ZIF-8之间的协同作用,促进了可见光的吸收以及反应物分子NO的吸附,从而提高了复合材料对NO的光催化氧化性能。

g-C_(3)N_(4),ZIF-8 and ZIF-8/g-C_(3)N_(4) composite photocatalysts with different mass ratios were prepared by thermal polymerization method and in-situ deposition method,respectively.The structural properties of prepared samples were characterized by using X-ray diffraction(XRD),scanning electron microscope(SEM),transmission electron microscope(TEM),and X-ray photoelectron spectroscopy(XPS),etc.The results showed that the ZIF-8/g-C_(3)N_(4) composite did not destroy the original crystal structure and morphology of ZIF-8 and g-C_(3)N_(4),and ZIF-8 formed a heterojunction with g-C_(3)N_(4).The BET specific surface area of ZIF-8/g-C_(3)N_(4) was improved more than 30 times compared with g-C_(3)N_(4).The results of photocatalytic oxidation of NO showed that 12.5%-ZIF-8/g-C_(3)N_(4) exhibited the best removal efficiency of NO and no toxic intermediate NO_(2) production,and it had the most excellent photocatalytic activity with the nitric oxide removal efficiency of 55.1%.The mechanism study showed that the formed heterostructure not only inhibited the recombination of photogenerated charge carriers,but also promoted the absorption of visible light and the adsorption of reactant molecular NO due to the synergy between ZIF-8 and g-C_(3)N_(4),thus improving the photocatalytic oxidation performance of NO.