ZnO/g-C_(3)N_(4)异质结光催化材料的制备及对吡啶的降解

Preparation of ZnO/g-C_(3)N_(4) heterojunction photocatalytic material and its degradation of pyridine

采用蒸发溶剂-高温热聚合法制备了ZnO/g-C_(3)N_(4)异质结光催化材料,采用XRD、FTIR、TEM、XPS、UV-vis DRS、PL、TPC和EIS等表征技术对其进行了详细系统的表征,评价了ZnO/g-C_(3)N_(4)光催化降解吡啶的活性和稳定性,采用L_(9)(3^(4))正交实验考察了不同因素对光催化性能的影响,并对光催化机理进行了探讨。XPS和TEM结果证明了ZnO和g-C_(3)N_(4)之间异质结的形成,异质结的形成有效促进了光电子-空穴的分离,提高了光吸收,拓宽了光谱范围。在ZnO/g-C_(3)N_(4)复合光催化剂投加量为50 mg、ZnO与g-C_(3)N_(4)质量比为1∶2、吡啶初始质量浓度为20 mg/L和体系p H为7.0的条件下,可见光照射60 min后ZnO/g-C_(3)N_(4)对吡啶的光催化降解率达到了98.9%,循环使用5次后光催化降解率为97.3%,具有良好的稳定性。ZnO/g-C_(3)N_(4)光催化降解吡啶主要依赖于活性基团超氧自由基(·O_(2)^(-))和空穴(h^(+))的作用。

The ZnO/g-C_(3)N_(4) heterojunction photocatalytic materials were prepared by evaporation solvent⁃high temperature thermal polymerization method.They were systematically characterized by XRD,FTIR,TEM,XPS,UV-vis DRS,PL,TPC and EIS.The activity and stability of ZnO/g-C_(3)N_(4) photocatalytic degradation of pyridine were evaluated.The effects of differ⁃ent factors on the photocatalytic performance were investigated by L_(9)(3^(4))orthogonal experiment,and the photocatalytic mechanism was discussed.XPS and TEM results proved the formation of heterojunction between ZnO and g-C_(3)N_(4).The forma⁃tion of heterojunction effectively promoted the separation of photoelectron-holes,improved the light absorption and broad⁃ened the spectral range.Under the conditions of ZnO/g-C_(3)N_(4) composite photocatalyst dosage of 50 mg,ZnO/g-C_(3)N_(4) mass ra⁃tio of 1∶2,pyridine initial concentration of 20 mg/L and system pH of 7.0,the photocatalytic degradation rate of pyridine by ZnO/g-C_(3)N_(4) reached 98.9%after visible light irradiation for 60 min,and the photocatalytic degradation rate was 97.3%af⁃ter 5 cycles,which had good stability.The photocatalytic degradation of pyridine by ZnO/g-C_(3)N_(4) was mainly dependent on the action of superoxide radicals(·O_(2)^(-))and holes(h^(+)).