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风雨182木虫 (正式写手)
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图5-5是N、S单组分掺杂和N-S共掺杂TiO2与纯TiO2对甲基橙的降解速率比较。由图中可以看出当焙烧温度为450 ℃时，N、S或N-S共掺杂的TiO2对甲基橙的降解率均比纯TiO2高。其中，N-S共掺杂TiO2对甲基橙的降解率最高，N掺杂TiO2对甲基橙的降解率次之。在光照20 min后，N-S共掺杂TiO2对甲基橙的降解率几乎达到100 %；N掺杂TiO2对甲基橙的降解率达到98%左右；S掺杂TiO2对甲基橙的降解率在70 %左右，但光照50 min后，甲基橙的降解率基本都达到100 %，而纯TiO2对甲基橙的降解率只达到85 %。结合样品的XRD图可知，N-S共掺杂和S掺杂TiO2光催化剂的晶型主要是锐钛矿型，N掺杂TiO2主要呈金红石型，纯TiO2中锐钛矿型和金红石型比例相当。一般来说，锐钛矿型TiO2比金红石型TiO2的光催化活性高。这是因为锐钛矿型的TiO2禁带宽度为3.2 eV，金红石型的TiO2的禁带宽度为3.0 eV，锐钛矿型TiO2在光催化过程中产生的电子空穴对的氧化还原能力较强。另外，由于金红石型TiO2由锐钛矿型通过高温灼烧得到，所以金红石型TiO2易于团聚且颗粒较大，比表面积减小，在降解过程中产生的光生电子空穴对减少，从而造成光催化效率的降低。但光催化剂中存在一定比例的金红石相时，可以有效提高光生载流子的分离效率，促进光催化活性的提高。 请不要直接复制翻译软件结果！！！！ |
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哥们，还等呢？看看，成不。确认引号内容。
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风雨182(金币+30,VIP+0):谢谢你啊哥们以后还找你 9-30 16:00
风雨182(金币+30,VIP+0):谢谢你啊哥们以后还找你 9-30 16:00
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The degradation rates of “methyl orange" with the help of four kinds of catalysts, pure TiO2, N-doped TiO2, S-doped TiO2 and N+S co-doped TiO2, are shown in Fig. 5-5 for comparison. From the figure, it can be seen that all degradation rates corresponding to three doped TiO2 catalysts are higher than that corresponding to the pure TiO2 catalyst at the calcination temperature of 450 degree C. The degradation rate corresponding to the N+S co-doped TiO2 catalyst is the highest, and the rate corresponding to the N-doped TiO2 the second among all rates. After being irradiated by light for 20 minutes, the degradation rate corresponding to the N+S co-doped TiO2 catalyst almost reach to 100%, the rate corresponding to the N-doped to about 98%, and the rate corresponding to the S-doped to about 75%. However, after being irradiated by light for 50 minutes, all degradation rates corresponding to three doped TiO2 catalysts roughly reach to 100% and the rate corresponding to the pure TiO2 only to about 85%. X-ray diffraction patterns show us that anatase is the main phase in both N+S co-doped and S-doped TiO2 catalysts, and rutile the main phase in the N-doped TiO2 catalyst. The content of the anatase phase is equal to that of rutile phase in the pure TiO2 catalyst. Generally speaking, the catalyses of anatase TiO2 is stronger than that of rutile TiO2 because the forbidden gap of anatase TiO2, which is equal to 3.2eV, is larger than that of rutile TiO2 which is equal to 3.0 eV. The electron-hole pairs induced during the photocatalytic process of the anatase TiO2 possess a stronger ability of redox than that of rutile TiO2. On the other hand, all grains in the rutile TiO2 are apt to aggregate into larger clusters because the rutile TiO2 is converted from calcinating the anatase TiO2 at the high temperature. In addition, the average grain size is larger in rutile TiO2. Therefore, the number of photon-induced electron-hole pairs during the degradation process will becomes less resulting from the smaller "active surface area ratio", which thus contributes a lower photocatalytic efficiency for the rutile TiO2. However, a certain proportion of the rutile in the anatase TiO2 catalyst will effectively enhance the separation efficiency of photon-induced carriers and promote the improvement of photocatalytic activity. |
2楼2009-09-28 12:18:32
风雨182
木虫 (正式写手)
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3楼2009-09-28 14:34:48
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风雨182(金币+20,VIP+0):谢谢你啊欢迎以后继续参与 9-30 16:01
风雨182(金币+20,VIP+0):谢谢你啊欢迎以后继续参与 9-30 16:01
| Figure 5-5 shows the degradation rates of methyl orange for un-doped TiO2, N-doped TiO2, S-doped TiO2, as well as N-S co-doped TiO2. It can be seen that when the calcination temperature is 450℃, the degradation rates of methyl orange for N-, S-, doped and N-S codoped TiO2 are higher than that for the un-doped TiO2. The degradation rate for N-S co-doped TiO2 is the highest, and the N-doped TiO2 lies second. After being irradiated for 20 minutes, the degradation rate of methyl orange for N-S co-doped TiO2 almost achieves 100%, N-doped one reaches about 98%, and S-doped one reaches about 75%. However, after being irradiated for 50 minutes, all degradation rates for the above three doped TiO2 roughly reach 100%, while the rate for the pure TiO2 only about 85%. With the aid of X-ray diffraction patterns, one can see that the main crystal phases for N-S co-doped and S-doped TiO2 catalysts are anatase phases, S-doped TiO2 catalysts is rutile one, while in un-doped TiO2 catalyst, the content of the anatase phase is equal to rutile phase. Generally, the photocatalytic activity for anatase TiO2 is higher than that of rutile TiO2, since the forbidden gap of anatase TiO2 is 3.2eV, while the rutile TiO2 3.0 eV, resulting in that the ability of redox for electron-hole pairs induced during the photocatalytic process is stronger for the former than that of the latter. On the other hand, as the rutile TiO2 is originated after calcinating the anatase TiO2 at the high temperature, thus, the rutile TiO2 is be prone to aggregate, then the grain size becomes larger, surface area ratio gets smaller, the number of photon-induced electron-hole pairs during the degradation process gets decreased, resulting in the degradation of the photocatalytic efficiency. However, a proportional of the rutile in the anatase TiO2 catalyst will effectively enhance the separation efficiency of Photo-generated Carriers and promote the photocatalytic activity. |
4楼2009-09-29 16:01:27