Highly efficient formation of visible light tunable TiO2-xNx photocatalysts and their transformation at the nanoscale
Highly efficient formation of visible light tunable TiO2-xNx photocatalysts and their transformation at the nanoscale
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DOI：
10.1021/jp030843n
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发表时间：
2004-01-29
影响因子：
3.3
通讯作者：
Chen, XB
中科院分区：
文献类型：
--
作者：
Gole, JL;Stout, JD;Chen, XB
使用简单的纳米级独家合成路线，可在室温下在几秒钟内生产出可在可见光区域吸收的 TiO2-N-x(x) 光催化剂。该光催化剂是通过使用烷基铵盐直接氮化锐钛矿型 TiO2 纳米结构而形成的。根据 TiO2 纳米颗粒团聚程度，获得具有催化活性的 TiO2-xNx 锐钛矿结构颗粒，其吸收起始点延伸至可见光区域 lambda - 550 nm。引入少量氯化物或硝酸盐形式的钯有利于进一步吸收氮，似乎导致部分相变，与乙酸盐相比显示出抗衡离子效应，并产生良好吸收近红外的材料。通过氯化物引入钯还有助于在整个 TiO2-xNx 晶格中形成小的四面体和八面体钯基微晶。令人惊讶的是，最终的 TiO2-xNx 产品中似乎没有掺入任何有机物。所得的光催化剂很容易光降解亚甲基蓝，并当它们以凝胶形式放置在表面时导致乙烯的催化氧化。与目前在纳米尺度上相当容易的氮化过程相比，我们观察到德固赛 P25 纳米粉末的硝化速度要慢得多，并且微米级锐钛矿或金红石 TiO2 粉末在室温下很少或没有直接氮化。因此，我们展示了一个例子，说明穿越纳米尺度如何极大地提高生产重要亚微米材料的效率。
Using a simple nanoscale exclusive synthesis route, TiO2-N-x(x) photocatalysts that can be tuned to absorb across the visible region are produced in seconds at room temperature. The photocatalysts are formed by employing the direct nitridation of anatase TiO2 nanostructures with alkylammonium salts. Depending on the degree of TiO2 nanoparticle agglomeration, catalytically active TiO2-xNx anatase structured particles are obtained whose absorption onset extends well into the visible region lambda - 550 nm. The introduction of a small quantity of palladium in the form of the chloride or nitrate facilitates further nitrogen uptake, appears to lead to a partial phase transformation, displays a counterion effect when compared also to the acetate, and produces a material absorbing well into the near-infrared. The introduction of palladium via the chloride also facilitates the formation of small tetrahedral and octahedral palladium-based crystallites throughout the TiO2-xNx lattice. Surprisingly, no organics appear to be incorporated into the final TiO2-xNx products. The resulting photocatalysts readily photodegrade methylene blue and lead to the catalytic oxidation of ethylene as they are placed as gels on surfaces. In contrast to the current nitridation process, which is quite facile at the nanoscale, we observe a much slower nitration of Degussa P25 nanopowders and little or no direct nitridation of micrometer-sized anatase or rutile TiO2 powders at room temperature. We thus demonstrate an example of how a traversal to the nanoscale can vastly improve the efficiency for producing important submicron materials.