超分子前体制备g-C3N4/g-C3N4同质结及光催化性能研究
收稿日期: 2021-05-20
网络出版日期: 2022-03-18
Study on preparation of g-C3N4/g-C3N4 homojunction by supramolecular precursor and its photocatalytic property
Received date: 2021-05-20
Online published: 2022-03-18
通过混合煅烧二氰二胺水热法和三聚氰胺-三聚氰酸共沉淀法制备的超分子前驱体,制备了兼具多孔纳米片和中空纳米管形貌的g-C3N4/g-C3N4同质结(CN-HP)。通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)、光致发光光谱(PL)等对光催化剂进行了表征。结果表明,CN-HP-1/1在75 min内对亚甲基蓝(MB)的降解率可达99.8%,伪一级动力学常数为4.02 h-1,是块体g-C3N4的5倍,同时单位比表面积的反应常数提升至单体的1.8倍。PL测试表明,合适比例的三聚氰胺-三聚氰酸(MCA-H、MCA-P)超分子制备的同质结,其光生电子-空穴复合率较单体g-C3N4进一步降低。自由基捕获实验表明,光生空穴是光催化降解过程中的主要活性物种,并结合X射线光电子能谱价带谱测试提出了Z型电子传输机制。
班昌胜 , 李军 , 金央 , 陈明 , 左龙涛 . 超分子前体制备g-C3N4/g-C3N4同质结及光催化性能研究[J]. 无机盐工业, 2022 , 54(3) : 125 -131 . DOI: 10.19964/j.issn.1006-4990.2021-0260
g-C3N4/g-C3N4 homojunction(CN-HP) with the morphology of porous nanosheets and hollow nanotubes was pre-pared from supramolecular precursor prepared by mixed calcination of dicyanodiamine hydrothermal method and melamine-cyanuric acid coprecipitation method.The photocatalyst was characterized by X-ray diffraction(XRD),scanning electron mi-croscopy(SEM),transmission electron microscopy(TEM),ultraviolet-visible diffuse reflectance(UV-Vis DRS),photolumi-nescence spectroscopy(PL),etc.The results showed that CN-HP-1/1 exhibited a degradation rate of 99.8% for methylene blue(MB) within 75 min,and the pseudo first-order kinetic constant was 4.02 h-1,which was 5 times that of bulk g-C3N4.And the reaction constant per unit specific surface area was increased to 1.8 times that of monomeric g-C3N4.The PL test showed that the photogenerated electron-hole recombination rate of the homojunction prepared by the appropriate ratio of MCA was lower than that of the monomer g-C3N4. Free radical capture experiments showed that photo-generated holes were the main active species in the photocatalytic degradation process.Combined with XPS valence band spectroscopy tests,it was proposed that the homojunction photocatalysts had a Z-scheme electron transport mechanism.
Key words: g-C3N4; supramolecular; homojunctions; photocatalysis
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