JCdS/ZnO复合半导体光催化剂的制备、表征及分解水制氢

Preparation & Characterization of CdS/ZnO Composite Semiconductors and Photocatalytic Decomposition of Water to Produce Hydrogen

在超声条件下,采用溶胶凝胶法制备Zn(OH)2溶胶,然后在其上沉积沉淀CdS,制备CdS/Zn(OH)2催化剂前驱体。前驱体分别在空气和氮气下焙烧,制得两种CdS/ZnO复合光催化剂。催化剂表征和分解水制氢实验结果表明,两种CdS/ZnO复合光催化剂在可见光区均有强吸收。空气条件下焙烧制得的光催化剂中有CdO存在,经XRF测量其组成为29.3%CdS-18.6%CdO/ZnO(物质的量分数),其光催化分解水制氢效果明显高于氮气下焙烧制得的光催化剂,平均产氢速率达5.2 mmol(h.gcat)-1。

Zn（OH）2 sols were prepared by sol - gel method and then nanoparticles of CdS were deposited on it under ultrasonic conditions all the time. Precursors of CdS/Zn（OH） 2 were calcined under air and N2 respectively to get two kinds of CdS/ZnO composite photocatalysts. The results of characterization of the catalysts mentioned above showed both of them had strong absorption in visible - light region. The photocatalyst calcined in air had peak of CdO by XRD and composition of 29.3% CdS - 18.6% CdO/ZnO（mol/mol） by XRF. The average rate of hydrogen evolution over 29.3% CdS - 18.6% CdO/ZnO reached 5.2mmol（h·gcat）^-1, much higher than over the photocatalyst calcined in N2. According to Sherrer equation, CdS in CdS/ZnO - air have smaller crystal size due to the presence of CdO which induces the blue shift of CdS absorption. More active sites and smaller crystal size of CdS in CdS/ZnO - air assume the higher hydrogen evolution.