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求做光催化高手翻译一段话
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| 钛酸锶钡之所以能作为光催化剂，与其自身的光电特性有关。它属N型半导体，其能带是不连续的，在充满电子的低能价带VB和空的高能导带CB之间存在一个禁带。当用能量等于或大于禁带宽度ES的光照射钛酸锶钡时，其价带上的电子(e-)就会被激发，越过禁带跃迁到导带，同时在价带上产生空穴(h+)，形成电子－空穴对。吸附“溶解”在钛酸锶钡表面的氧通过俘获电子形成•O2，而空穴则将吸附在钛酸锶钡表面的OH-和H2O氧化成HO•。生成的原子氧和氢氧自由基有很强的化学活性。HO•基团的氧化能力很强，有机物可以被其氧化分解，最终分解为二氧化碳和水；而原子氧能与多数有机物反应，使得有机物得到降解，同时能氧化细菌内的有机物，生成CO2和H2O，原子氧还能氧化有毒的无机物，使之在短时间内失去毒性。由图可以看出，BaTiO3对亚甲基蓝的降解效果最好，这与其光致发光谱信号最弱和带隙能量较低的结果一致。当BaTiO3中的部分Ba2+被Sr2+取代后，其光催化活性降低，可能是由于Sr的原子半径比Ba小，生成的光生电子与空穴更易复合。在5 mol/L NaOH溶液中比在2 mol/L 和10 mol/L NaOH溶液中制备的Ba0.7Sr0.3TiO3的光催化能力更强，0.5 g催化剂加入到200 ml 10 mg/L的亚甲基蓝溶液中，光催化反应120 min，其降解率达40%，这是由于图2-5(b)中5 mol/L NaOH溶液制得产品粒子的粒径更小，比表面积大，对光的吸收能力强，与被降解物接触更充分的原因。 |
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wypward(金币+2):欢迎新虫，谢谢参与 2010-06-03 17:34:38
xiangshang(金币+5, 翻译EPI+1):谢谢你的参与！ 2010-06-04 10:33:55
wypward(金币+2):欢迎新虫，谢谢参与 2010-06-03 17:34:38
xiangshang(金币+5, 翻译EPI+1):谢谢你的参与！ 2010-06-04 10:33:55
| BST is able to as a photocatalyst because of its own optical characteristics. It is a N-type semiconductor which the energy is not continuous, low-energy electrons in the filled valence band VB and the empty conduction band energy of a band gap between the CB. When using the energy band gap equal to or greater than the light irradiation ES BST, its price band of electronic (e-) will be excited over the band gap transition to the conduction band, while the valence band holes generated (h +), the formation of electron - hole pairs. Adsorption "dissolved" in the BST surface oxygen by trapping electrons • O2, while the hole will be absorbed on the surface of barium strontium titanate OH-and H2O oxidation of HO •. Generation of atomic oxygen and hydroxyl radicals have a very strong chemical activity. HO • a strong group of oxidation, the oxidation decomposition of organic matter can be finally broken down into carbon dioxide and water; the atomic oxygen reaction with most organic compounds, making organic matter are degraded, while the oxidation of organic matter in bacteria to produce CO2 and H2O , atomic oxygen oxidation of toxic inorganic substances can make in a short time to lose toxicity. Can be seen from the chart, BaTiO3 the degradation of methylene blue the best, this photoluminescence signal with the weakest and the band gap energy lower results. As part of BaTiO3 in the Sr2 + Ba2 + was replaced, their photocatalytic activity decreased, probably due to the atomic radius of Sr than Ba is small, light generated electron and hole Gengyi compound. In 5 mol / L NaOH solution than in the 2 mol / L and 10 mol / L NaOH solution prepared photocatalytic stronger Ba0.7Sr0.3TiO3, 0.5 g catalyst to 200 ml 10 mg / L methylene blue solution in the photocatalytic reaction 120 min, the degradation rate of 40%, which is due to map 2-5 (b) in 5 mol / L NaOH solution was prepared products smaller particle size, large surface area, light absorption ability, and the degradation products were more fully the reasons for exposure. |
2楼2010-06-03 17:29:10