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用丙烯酸酯和环氧树脂将亲水性的-OH和芳香性的苯环修饰到Pt/ZnS-CdS/SiO2催化剂表面,在不同气氛下进行热处理,得到了表面修饰并热处理后的Pt/ZnS-CdS/SiO2光催化剂,考察催化剂的可见光催化分解水产氢活性.结果表明修饰并热处理后催化剂活性不同程度的下降.XRD结果表明,修饰前后ZnS和CdS的特征衍射峰没有改变,但空气热处理致使催化剂晶型由立方晶型的CdS和六方晶型的ZnS向六方晶型的CdS和α-ZnS的转变,氢气气氛热处理致使催化剂的晶型向六方结构的固溶体Zn0.5Cd0.5S转变,未修饰的催化剂在空气和氢气中热处理后晶型发生了同样的转变.HRTEM结果表明表面修饰后催化剂平均粒径由18 nm减小为6 nm,仍以ZnS为外层,CdS为内层的核壳结构形态存在.紫外可见漫反射(UV-Vis DRS)结果表明,经修饰和热处理后的光催化剂在450～800 nm区间的光吸收增加,在空气中773 K煅烧后的催化剂的吸收限由480 nm红移至520 nm,而在氢气中于773 K煅烧后吸收限则由480 nm蓝移至420 nm.修饰后催化剂的羟基吸收强度增大,出现了苯环的特征吸收峰,这些官能团经热处理后发生了显著变化.红外光谱(IR)结果表明空气热处理导致部分含氧官能团发生了脱离,羟基吸收增强;氢气热处理导致C—O和C—O—C的吸收峰增强,同时催化剂表面发生碳化.热重差热分析(TG-DTA)与红外结果均证实了这种变化.产氢活性下降可能归结为表面羟基减少导致的在反应体系中的分散性和光生电荷的分离效率降低;催化剂表面的含氧官能团占据了催化活性位并且降低了颗粒在水溶液中的分散性.
Hydrophilic -OH and aromatic benzene rings were modified onto the surface of Pt / ZnS-CdS / SiO2 catalyst by using acrylic acid ester and epoxy resin, and then heat-treated in different atmospheres to obtain Pt / ZnS surface-modified and heat- The results showed that the activity of the catalyst decreased after modification and heat treatment.XRD results showed that the characteristic diffraction peaks of ZnS and CdS before and after modification did not change, but the air heat treatment caused The transformation of hexagonal CdS and α-ZnS from cubic crystalline CdS and hexagonal ZnS resulted in the transformation of the catalyst into the hexagonal solid solution Zn0.5Cd0.5S with the unmodified Of the catalyst in air and hydrogen after heat treatment the same transformation occurred.HRTEM results show that the average particle size of the surface modified catalyst decreased from 18 nm to 6 nm, still with ZnS as the outer layer, CdS as the inner core shell The results of UV-Vis DRS showed that the optical absorption of the modified and heat-treated photocatalysts increased in the range of 450-800 nm, and that of the catalysts calcined at 773 K in the air The absorption limit was red shifted from 480 nm to 520 nm, while the absorption limit shifted from 480 nm to 420 nm in hydrogen after calcination at 773 K. The hydroxyl absorption of the modified catalyst increased and the characteristic absorption peak of benzene ring appeared , These functional groups changed significantly after heat treatment.The results of infrared spectroscopy (IR) showed that some oxygen-containing functional groups were detached and the hydroxyl groups were enhanced by the heat treatment of air, and the absorption peaks of C-O and C-O-C were enhanced by hydrogen heat treatment, While the catalyst surface carbonation.Thermal heavy differential thermal analysis (TG-DTA) and infrared results confirm this change.Hydrogen production activity may be attributed to the reduction of surface hydroxyl groups in the reaction system dispersion and photo-induced charge separation The efficiency is reduced; the oxygen-containing functional groups on the catalyst surface occupy the catalytically active sites and reduce the dispersibility of the particles in the aqueous solution.