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woshibadchen金虫 (正式写手)
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50金币求助光催化离子掺杂一问题
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在看光催化文献经常看到这样一段话,例如在TiO2中掺入某种离子,对掺杂离子对这种催化剂的活性高低这样解释:当离子的掺杂量低于最佳掺杂量时，由于缺少足够多的电子-空穴的捕获位使催化剂的光催化活性不高;当离子的掺杂量高于最佳掺杂量时，一方面，高浓度的掺杂可能成为电子-空穴对的复合中心；使得光催化活性降低。 请各位高手解释一下,"高浓度的掺杂可能成为电子-空穴对的复合中心"这句话的科学依据是什么,能否解释一下,我看文献都是这样大致解释一下,能否详细的说一下啊.谢谢各位. 各位高手最好能用英语回答,最好能给出相关文献,谢谢 [ Last edited by woshibadchen on 2009-6-7 at 16:24 ] |
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gangqin
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gangqin
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2楼2009-06-07 17:16:46
gangqin
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Abstract: Mesoporous material MCM-41 with several morphologies by self-assembly from the precursor have been controllably synthesized in diluted medium system. Spherical MCM-41silica with an average size from nano-scale to micro-scale was produced through different concentration of the reactant and the kind of the catalysis. In this paper, self-assembly chemistry was used to produce hexagonal mesoscopic nanotube array, periodic nano-wire and TiO2/C nano multilayer film by the combination of the precursor and the traditional ceramic technique. These materials will be the candidate for field emission, quantum interference, hydrogen storage material and Lithium fuel cell. Applying three kinds of template reagents, hexadecylamine, citric acid and collagen molecular, lamellar and nano-crystal calcium phosphate were synthesized under suitable condition respectively. It was found the 16-amine and acidic medium could induce mesoscopic lamellar calcium phosphate, while citric acid and collagen in basic medium to nanocrystal, which is key to insight the biological evolution from invertebrates to vertebrates. Also the synthesis of other functional materials of by self-assembly was done, YBCO nanowire by an inversed micelle and Eu-doped silica microsphere as photonic crystal unit. The cupped gap of photonic crystal was found in Eu-doped silica. Base on the emission and exited spectrum, it can be interpreted as the mixture valets of Euion and the energy transfers. |
3楼2009-06-07 17:17:19
wenxue_j
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Applying three kinds of template reagents, hexadecylamine, citric acid and collagen molecular, lamellar and nano-crystal calcium phosphate were synthesized under suitable condition respectively. It was found the 16-amine and acidic medium could induce mesoscopic lamellar calcium phosphate, while citric acid and collagen in basic medium to nanocrystal, which is key to insight the biological evolution from invertebrates to vertebrates. Also the synthesis of other functional materials of by self-assembly was done, YBCO nanowire by an inversed micelle and Eu-doped silica microsphere as photonic crystal unit. The cupped gap of photonic crystal was found in Eu-doped silica. Base on the emission and exited spectrum, it can be interpreted as the mixture valets of Euion and the energy transfers |
4楼2009-06-07 17:30:45
woshibadchen
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5楼2009-06-07 17:59:36
superman900
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woshibadchen(金币+20,VIP+0):谢谢了,兄弟 6-8 09:49
woshibadchen(金币+20,VIP+0):谢谢了,兄弟 6-8 09:49
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建议看看固体物理化学,掺杂导致能带结构改变,在价带和倒带之间形成很多中间态,电子跃迁后很容易发生热迟豫跳转到这些能带,进一步迟豫或跃迁回到价带跟空穴结合. 很明显,中间态越多,热迟豫发生的机率越大,即电子空穴复合加重. 一定程度内,我们希望有这些中间态,因为中间态使得电子跃迁几率增大;但是浓度过大,跃迁后很快又复合了.这是矛盾. 这种解释是定性的,没见过定量的解释,估计你也查不到任何资料.这似于常识,只要你具备一定的物理知识,很容易理解,因此文献上不做过深解释. |
6楼2009-06-07 22:05:17
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