Pd修饰对Cd0.8Zn0.2S/SiO2光催化甘油水溶液制氢性能的影响

用等体积浸渍法制备了不同Pd负载量的Pd/Cd_0.8Zn_0.2S/SiO₂光催化材料,采用XRD、H₂-TPR、XPS、UV-vis DRS和光催化反应评价等方法对光催化材料的表面结构、光吸收性能以及光催化甘油水溶液制氢反应性能进行了考察。研究结果表明,ZnS与CdS在SiO₂表面形成了Cd_0.8Zn_0.2S固溶体,金属Pd负载未对固溶体Cd_0.8Zn_0.2S/SiO₂的结构造成影响;金属Pd修饰明显地提高了原固溶体的光响应性能,拓展了其吸光域,增强了吸光效率。金属Pd修饰后,Cd_0.8Zn_0.2S/SiO₂的光解甘油水溶液产氢速率显著提高,Pd负载量为0.5%的Pd/Cd_0.8Zn_0.2S/SiO₂具有最佳的光催化甘油水溶液制氢性能,其在紫外光照射下的氢气生成速率为831 μmol/h,较未负载时提高了近四倍;模拟太阳光下为153 μmol/h,较未负载时提高了近两倍。

Effect of Pd-modification on photocatalytic H2 evolution over Cd0.8Zn0.2S/SiO2 from glycerol solution

A series of Pd/Cd_0.8Zn_0.2S/SiO₂ photocatalysts were prepared by incipient wet impregnation. The catalysts were characterized by XRD, H₂-TPR, XPS, and UV-vis DRS and used in the photocatalytic evolution of H₂ from glycerol and water mixture; the effects of Pd loading on the surface structure, photo absorption and H₂ evolution rate were investigated. The results showed that the chemical interaction between ZnS and CdS results in the formation of Cd_0.8Zn_0.2S solid solution on the surface of SiO₂; after the modification with Pd, the light absorption region of Cd_0.8Zn_0.2S/SiO₂ is expanded and the photo absorption efficiency is enhanced obviously. The loading of Pd exhibits significant influence on the rate of photocatalytic H₂ evolution; over 0.5%Pd/Cd_0.8Zn_0.2S/SiO₂ with a Pd loading of 0.5%, the maximum hydrogen production rates under UV light irradiation and under solar-simulated light irradiation reach 831 μmol·h^-1 and 153 μmol·h^-1, respectively, which are almost 4 times and 2 times higher than those obtained over unmodified Cd_0.8Zn_0.2S/SiO₂ under UV and solar-simulated light irradiation, respectively. The superior photocatalytic performance of Pd/Cd_0.8Zn_0.2S/SiO₂ can be partly related with the improvement of photo absorption, the enhancement in chemisorption and activation of H₂O and the increase in separation efficiency of photo induced electron-hole arising from the Pd modification.