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hushaozheng金蟲(chóng) (小有名氣)
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[求助]
有關(guān)光催化劑p-n結(jié)問(wèn)題,誰(shuí)能幫解釋一下? 已有2人參與
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最近看文獻(xiàn),是 關(guān)于BiOI-C3N4異質(zhì)結(jié)催化劑的,有這么一段話,原文如下: When p-type BiOI and n-type p-g-C3N4 are in contact, since the CB potential of p-g-C3N4 is more negative than that of BiOI, the electrons will diffusion from p-g-C3N4 to BiOI, resulting in accumulation of negative charges in BiOI close to the junction. At the same time, the holes transfer from BiOI top-g-C3N4, leaving a positive section in p-g-C3N4 near the junction. With equilibration of BiOI and p-g-C3N4 Fermi levels, the diffusion of electrons from p-g-C3N4 to BiOI stops. Meanwhile, the energy bands of BiOI shift upward along the Fermi level (EFp) and those of the p-g-C3N4 shift downward along its Fermi level (EFn), as shown in Fig. 9b. As a result, the CB bottom of BiOI became higher than that of p-g-C3N4. Under visible-light irradiation, both BiOI and p-g-C3N4 absorb photons of energy greater than the corresponding band gap energy, which excite the electrons in the VB to the CB and leave holes in the VB. The electrons in the conduction band of the p-BiOI are then transferred to the n-type p-g-C3N4, and the holes remain in the valence band of BiOI. The migration of photogenerated carriers can be promoted by the inner electric field established at the heterojunction interfaces. 我理解大概是這個(gè)意思:C3N4的導(dǎo)帶比BiOI的導(dǎo)帶更負(fù),電子從C3N4傳遞到BiOI,價(jià)帶BiOI比C3N4更正,所以空穴從BiOI傳向C3N4,當(dāng)達(dá)到某種平衡后,價(jià)帶和導(dǎo)帶位置會(huì)發(fā)生變化,使情況正好相反,電子從BiOI傳遞到C3N4,空穴從C3N4傳向BiOI。這是為什么呢?有沒(méi)有大牛能給系統(tǒng)又簡(jiǎn)明直白的解釋一下,謝謝! |
g-C3N4 |

金蟲(chóng) (小有名氣)
金蟲(chóng) (小有名氣)

木蟲(chóng) (正式寫(xiě)手)
| 當(dāng)二者接觸的時(shí)候,C3N4的導(dǎo)帶比BiOI的導(dǎo)帶更負(fù),電子從C3N4擴(kuò)散至BiOI,從而導(dǎo)致在二者接觸處(異質(zhì)結(jié)處)靠近BiOI的一邊有負(fù)電荷積累;同時(shí),空穴從BiOI擴(kuò)散至C3N4,導(dǎo)致在異質(zhì)結(jié)靠近C3N4的一邊有正電荷積累;當(dāng)二者的費(fèi)米能級(jí)達(dá)到穩(wěn)定/平衡的時(shí)候,這種電荷擴(kuò)散/傳遞停止。與此同時(shí),BiOI的能帶隨其費(fèi)米能級(jí)上升而C3N4的則下降(as shown in Fig. 9b)。因此,BiOI導(dǎo)帶的底端高于了C3N4導(dǎo)帶的底端。在可見(jiàn)光照射下,二者皆可吸收能量大于其相應(yīng)的帶差能量的光子,湊個(gè)熱激發(fā)了價(jià)帶電子向?qū)мD(zhuǎn)移,從而在價(jià)帶產(chǎn)生空穴。這樣,BiOI的導(dǎo)帶電子被傳送至C3N4,而其價(jià)帶則留下了空穴。這種光生載流子的遷移也可以被在異質(zhì)結(jié)形成的內(nèi)部電場(chǎng)所強(qiáng)化。 |
木蟲(chóng) (正式寫(xiě)手)
木蟲(chóng) (正式寫(xiě)手)
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