Abstract: The principle of p-n type semiconductor composite photocatalysts is discussed as a strategy to develop efficient photocatalysts for water splitting. Composite of p-type and n-type semiconductor has an advantage in taking full use of each semiconductor's function of oxidation and reduction, which could facilitate the photo-induced electron/hole pairs' separation by the inner electric field, enhancing the photocatalytic efficiency of the system. CuCrO₂ was synthesized by a novel combustion reaction method with glycerin as fuel, and WO₃ was prepared by the tungsten acid decomposition method. The configurations CuCrO₂-WO₃ and Ru/(CuCrO₂-WO₃) were successfully prepared by mechanical grinding and heat-treatment. The prepared samples were characterized by using X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance (UV-vis DR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of CuCrO₂, WO₃, CuCrO₂-WO₃ and Ru/(CuCrO₂-WO₃) were evaluated under xenon lamp irradiation. The factors including pH of grinding media and Ru loading were also investigated. When glycerin was used as the sacrificial reagent under xenon lamp irradiation, CuCrO₂ or WO₃ powders alone was not able to catalyze H₂ generation from water splitting, while coupled photocatalysts of CuCrO₂-WO₃ displayed remarkable photocatalytic activity. The improvement of photocatalytic activity was attributed to the formation of p-n junctures at the interface of CuCrO₂-WO₃. When grinding media was at pH 8, dispersion of WO₃ was particularly better, which contributed to more efficient compounding of the two powders and better activity of the composite as a consequence. Ru loading as cocatalyst also remarkably enhanced photocatalytic hydrogen production. The 0.5% (mass) Ru/(CuCrO₂-WO₃) exhibited better photocatalytic activity for splitting pure water into hydrogen under 300W xenon lamp irradiation, on which H₂ production was about 10 μmol for 3 h.

Key words: water splitting, photocatalysis, p-n composite, hydrogen, catalyst

摘要： 作为分解水制氢用光催化剂，p-n半导体物质的复合体具有较好的开发前景。燃烧法合成了p型半导体物质CuCrO₂，钨酸分解法合成了n型半导体物质WO₃，在此基础上经机械研磨及热处理的方法制备了CuCrO₂-WO₃和Ru/（CuCrO₂-WO₃）复合光催化剂。对制得的样品进行了X射线衍射（XRD）、紫外可见漫反射（UV-Vis DR）、扫描电镜（SEM）及X射线光电子能谱（XPS）表征分析。测定了CuCrO₂、WO₃、CuCrO₂-WO₃及Ru/（CuCrO₂-WO₃）在氙灯照射下的产氢活性，考察了研磨介质pH及钌负载量对CuCrO₂-WO₃光催化活性的影响。实验结果表明，CuCrO₂和WO₃单独使用时几乎没有活性，而复合催化剂CuCrO₂-WO₃在以甘油为电子给体的情况下具有产氢活性，研磨介质pH对复合催化剂的活性影响较大；负载钌后CuCrO₂-WO₃的活性得到进一步的提高，能分解纯水放出氢气，以0.5%Ru/（CuCrO₂-WO₃）为光催化剂，在300W氙灯照射下，3 h内分解纯水放出氢气约10 μmol。

关键词: 分解水, 光催化, p-n复合, 氢, 催化剂