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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >An effective approach for modifying carbonaceous materials with niobium single sites to improve their catalytic properties
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An effective approach for modifying carbonaceous materials with niobium single sites to improve their catalytic properties

机译：改性含铌单点碳质材料以提高其催化性能的有效方法

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摘要

In this paper we show a very simple route for the incorporation of catalytically active niobium species on the surface of carbon materials, such as graphene oxide, carbon nanotubes and activated carbon. Some existing methods of incorporating a transition metal on a support have involved co-precipitation or wet impregnation, to obtain the corresponding oxides. These methods, however, cause reduction in the specific area of the support and can also form large metal oxide particles with loss of metal exposure. Therefore, here we present a novel way to add catalytically active species on the surfaces of different types of carbon through the formation of interaction complexes between the metal precursor and the functional groups of the carbon matrix. Because of the excellent catalytic properties exhibited by the niobium species we choose the NH4[NbO(C2O4)(2)(H2O)(2)]center dot 2H(2)O salt as the model precursor. The characterization by XPS reveals the presence of the niobium species indicated by the displacement of the peaks between 206-212 eV related to the oxalate species according to the spectrum from pure niobium oxalate. Images obtained by TEM and SEM show the typical morphologies of carbonaceous materials without the niobium oxide formation signal, which indicates the presence of niobium complexes as isolated sites on the carbon surfaces. This new class of materials exhibited excellent properties as catalysts for pollutant oxidation. The presence of Nb promotes the catalytic activation of H2O2 generating hydroxyl radicals in situ, which allows their use in the organic compound oxidation processes. Tests for DBT oxidation indicate that Nb significantly improves the removal of such pollutants in biphasic reactions with removal around 90% under the tested conditions. Theoretical calculations showed that the most favorable adsorption model is an ionic complex presenting Delta G = -108.7 kcal mol(-1) for the whole adsorption process.
机译：在本文中，我们展示了一种非常简单的途径，可将催化活性铌物质掺入碳材料表面，例如氧化石墨烯，碳纳米管和活性炭。将过渡金属掺入到载体上的一些现有方法涉及共沉淀或湿浸渍，以获得相应的氧化物。然而，这些方法引起载体比表面积的减小，并且还可以形成大的金属氧化物颗粒而损失金属暴露。因此，在这里，我们提出了一种通过在金属前驱物和碳基质的官能团之间形成相互作用络合物，在不同类型的碳表面添加催化活性物质的新方法。由于铌物种具有出色的催化性能，我们选择NH4 [NbO（C2O4）（2）（H2O）（2）]中心点2H（2）O盐作为模型前体。 XPS的表征表明，根据纯草酸铌的光谱，与草酸盐物种相关的峰206-212 eV之间的峰位移表明存在铌物质。通过TEM和SEM获得的图像显示了不含铌氧化物形成信号的碳质材料的典型形态，这表明存在铌络合物作为碳表面上的分离位点。这类新型材料具有出色的性能，可作为污染物氧化的催化剂。 Nb的存在促进了H2O2的催化活化，从而原位生成羟基自由基，从而使其可用于有机化合物的氧化过程。 DBT氧化测试表明，Nb可以显着改善双相反应中此类污染物的去除，在测试条件下的去除率约为90％。理论计算表明，最有利的吸附模型是在整个吸附过程中呈现出Delta G = -108.7 kcal mol（-1）的离子络合物。

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