CuCrO_2-WO_3的制备及光催化产氢性能

Preparation of CuCrO_2-WO_3 and its photocatalytic performance for hydrogen production

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10μmol。

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/（CuCrOz-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, CHCIO2-WO3 and Ru/（CuCIO2-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 HE generation from water splitting,while coupled photocatalysts of CuCrO2-W03 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.