Improved Photocatalytic Hydrogen Production by Structure Optimized Nonstoichiometric Y2Ti2O7
Improved Photocatalytic Hydrogen Production by Structure Optimized Nonstoichiometric Y2Ti2O7
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DOI：
10.1002/cctc.201200148
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发表时间：
2012-11
期刊：
影响因子：
4.5
通讯作者：
O. Merka;D. Bahnemann;M. Wark
中科院分区：
文献类型：
--
作者：
O. Merka;D. Bahnemann;M. Wark
采用水相溶胶-凝胶法制备了Ti/Y比为0.95~1.15的非化学计量比的Y2Ti2O7焦绿石，并在不同温度下进行了热处理。用X-射线衍射仪、UV/Vis反射光谱和电子显微镜对合成的催化剂进行了表征。这些样品被负载了作为助催化剂的纳米Rh或Ph，并在甲醇作为牺牲剂的情况下进行了光催化制氢测试。结果表明，Ti/Y比和退火温度对Y2Ti2O7结构中的阳离子晶格畸变率有显著影响。通过对这些参数的优化，最大限度地减少了以Y和Ti晶格位置互换为特征的本征阳离子扭曲。在产氢测试反应中对材料的探测表明，焦绿石复合氧化物的光催化活性明显取决于阳离子晶格扭曲，并且可以进行相当大的调节。
Nonstoichiometric Y2Ti2O7 pyrochlores with Ti/Y ratios ranging from 0.95 to 1.15 were prepared by an aqueous sol–gel method and annealed at different temperatures. These synthesized catalysts were characterized by X‐ray diffraction, UV/Vis reflectance spectroscopy, and electron microscopy. The samples were loaded with nanoparticles of rhodium or platinum acting as co‐catalysts and tested for photocatalytic hydrogen production in the presence of methanol as sacrificial agent. It was found that the cationic lattice distortion in the Y2Ti2O7 structure is significantly influenced by the Ti/Y ratio and the annealing temperature. By optimization of these parameters, the intrinsic cationic distortion characterized by yttrium and titanium interchanging their lattice positions was minimized. Probing the materials in the hydrogen production test reaction revealed that the photocatalytic activity of pyrochlore mixed oxides is clearly determined by the cationic lattice distortion and can be tuned considerably.