噻吩环修饰氮化碳空心球的制备及其可见光催化性能

Preparation and Photocatalytic performance of thiophene-ring modified carbon nitride hollow spheres

以噻吩基团分子为聚合单体,低温溶剂热法一步合成噻吩环修饰的氮化碳空心球光催化剂.采用XRD、SEM、XPS、UV-Vis DRS、PL等测试方法对催化剂的结构、形貌、光电响应等进行了表征.结果表明,适量的噻吩环嵌入氮化碳骨架不影响产物空心球形貌,尽管降低了长程聚合度,但增加了球体表面缺陷,拓展了可见光吸收范围,缩小了带隙宽度,增强了光生电荷的产生密度并有效抑制了光生电子-空穴的复合,显著增强了光催化反应性能.通过光催化还原水中Cr^(6+)、光解水制氢和降解甲基橙的测试表明,噻吩环修饰后的CNS-2具有显著增强的光催化活性,其反应速率分别是未修饰氮化碳CN的2.5、3.8、1.6倍.而光生e^(−)和间接生成的·O_(2)^(-)分别是发生还原和氧化反应的主要活性物种.

Thiophene-ring modified carbon nitride hollow sphere photocatalysts(CNS)were synthesized by one-step low-temperature solvothermal method using thiophene group-containing molecules as monomers.The structure,morphology and optoelectronic properties of the catalysts were characterized by XRD,SEM,XPS,UV-Vis DRS,PL and others.The results show that appropriate amount of thiophene-rings embedded in the carbon nitride framework does not affect the hollow spherical morphology of the products,the long-range polymerization degrees of them are reduced,but it increases the surface defects of the spheres,expands the visible light absorption range,narrows the band gap,enhances the generation density of photogenerated charges and effectively inhibits the recombination of photogenerated electron-holes,therefore enhances the photocatalytic performances significantly.The photocatalytic reduction of Cr^(6+)in aqueous solution,water splitting for hydrogen production,and methyl orange degradation tests show that CNS-2 modified by thiophene-ring performs much enhanced photocatalytic activity,and its reaction rate was 2.5,3.8 and 1.6 times that of unmodified carbon nitride(CN),respectively.Pphotogenerated e^(−)and indirectly generated·O_(2)^(-)are the main active species for reduction and oxidation reactions,respectively.