一种C_(3)N_(4)光催化剂的制备及其对四环素类抗生素的降解

Preparation of a C_(3)N_(4) photocatalyst and its degradation of tetracycline antibiotics

以单一尿素为前驱体,通过热聚合制备了C_(3)N_(4),并通过SEM、XRD、XPS、FT-IR、UV-Vis等分析表征了所制备的C_(3)N_(4)材料的结构、成分、光学性能和光催化活性.结果发现制备的C_(3)N_(4)具有花状的多孔纳米片结构和大的比表面积.制备的C_(3)N_(4)在氙灯320~780nm的照射下,对盐酸四环素(TCH)的降解表现出良好的光催化活性,60min内降解率达到99.60%.自由基淬灭实验的结果表明,·O_(2)^(-)、^(1)O_(2)和h^(+)是TCH降解的主要原因.对比试验和DFT理论计算分析发现,以尿素为原料制备的C_(3)N_(4)比三聚氰胺为原料制备的M-C_(3)N_(4)光催化效果优异是归因于C_(3)N_(4)具有花状的多孔结构,更大比表面积以更多的活性位点和氧空位.此外,制备的催化剂C_(3)N_(4)对四环素类的抗生素(盐酸金霉素(CTC)和土霉素(OTC))具有类似的催化效果.进一步通过分析光催化氧化中间产物,提出了TCH可能的降解路径.

In this study,C_(3)N_(4) was fabricated by thermal polymerization using a single urea as a precursor,for which the structure,composition,optical properties and photocatalytic activity of the prepared C_(3)N_(4) materials were characterized by SEM,XRD,XPS,FT-IR and UV-Vis analyses.The as-fabricated C_(3)N_(4) was found to display a flower-like porous nanosheet structure and a large specific surface area.The C_(3)N_(4) exhibited good photocatalytic activity for the degradation of tetracycline hydrochloride(TCH)under the irradiation of xenon lamp at 320~780nm,and the degradation rate reached 99.60% within 60min.The results of free radical quenching experiments showed that·O_(2)^(-)、^(1)O_(2) and h^(+)were the main causes of TCH degradation.Further analysis by comparative tests and DFT theoretical calculations revealed that the superior photocatalytic effect of C_(3)N_(4) prepared from urea than M-C_(3)N_(4) prepared from melamine was attributed to the flower-like porous structure of C_(3)N_(4) with larger specific surface area for more active sites and oxygen vacancies.Furthermore,the prepared catalyst C_(3)N_(4) showed similar catalytic effect on tetracycline-based antibiotics(chrysomycin hydrochloride(CTC)and oxytetracycline(OTC)).Further,the possible degradation pathways of TCH were proposed by analyzing the photocatalytic oxidation intermediates.