本文選題：石墨相氮化碳 + 環(huán)境光催化��； 參考：《湖北工業(yè)大學(xué)》2017年碩士論文

【摘要】：作為一種可見(jiàn)光響應(yīng)的非金屬聚合物半導(dǎo)體材料,石墨相氮化碳(g-C3N4)在環(huán)境光催化領(lǐng)域具有廣闊的應(yīng)用前景。然而未經(jīng)修飾的g-C3N4存在著可見(jiàn)光響應(yīng)范圍小、光生電子-空穴容易發(fā)生復(fù)合、可見(jiàn)光光催化活性低等缺陷,不利于實(shí)際應(yīng)用。本論文在貴金屬Au和半導(dǎo)體CdS分別修飾g-C3N4的基礎(chǔ)上,先后采用光還原法和生物分子輔助法制備了具有高效光催化活性的g-C3N4基復(fù)合材料。在此基礎(chǔ)上,采用調(diào)控Au含量和碳包覆的手段進(jìn)一步改善其光催化性能。本論文的具體研究?jī)?nèi)容和結(jié)果如下:(1)采用兩步光還原法制備了CdS/Au/g-C3N4復(fù)合材料。研究發(fā)現(xiàn)CdS/Au/g-C3N4復(fù)合材料中同時(shí)存在兩種結(jié)構(gòu):CdS-g-C3N4異質(zhì)結(jié)與CdS-Au-g-C3N4全固態(tài)Z型結(jié)構(gòu)。光催化降解羅丹明B的結(jié)果表明,CdS/Au/g-C3N4具有比Au/g-C3N4與CdS/g-C3N4更高的光催化活性,這可能是由于CdS/Au/g-C3N4中的全固態(tài)Z型結(jié)構(gòu)具有更高的光生電子-空穴分離效率、高的光催化氧化還原性和可見(jiàn)光吸收能力。(2)利用生物分子半胱氨酸輔助法原位構(gòu)建了Au@CdS/g-C3N4復(fù)合材料。其中CdS與Au之間依靠氨基(-NH2)相互連接,構(gòu)建了Au@CdS核殼結(jié)構(gòu)并負(fù)載在g-C3N4表面,避免了CdS-g-C3N4異質(zhì)結(jié)的出現(xiàn),形成了CdS-Au-g-C3N4全固態(tài)Z型結(jié)構(gòu)以及Au@CdS核殼結(jié)構(gòu)。在光催化降解苯酚和甲基橙的過(guò)程中,Au@CdS/g-C3N4復(fù)合材料體現(xiàn)出了良好的光催化活性及穩(wěn)定性。(3)通過(guò)進(jìn)一步調(diào)控Au含量,抑制了Au@CdS/g-C3N4復(fù)合材料中Au@CdS之間的團(tuán)聚現(xiàn)象,使Au@CdS尺寸更加細(xì)小且均勻分布于g-C3N4表面,形成了單一的CdS-Au-g-C3N4全固態(tài)Z型結(jié)構(gòu),促進(jìn)了光生電子-空穴的分離,有效提高了Au@CdS/g-C3N4的光催化活性。采用水熱碳化法獲得的C/Au@CdS/g-C3N4復(fù)合材料,其表面的非晶碳薄膜具有良好的吸附性能,有利于污染物分子在復(fù)合材料表面的富集,在加速污染物的光催化降解過(guò)程的同時(shí),也加快了光生氧化物物種如空穴、超氧陰離子以及羥基自由基的消耗速率,從而也有效的抑制了Au@CdS的光腐蝕現(xiàn)象。(4)復(fù)合材料光催化性能的對(duì)比結(jié)果表明,在生物分子輔助的基礎(chǔ)上,通過(guò)調(diào)控Au含量和碳包覆獲得的C/Au@CdS/g-C3N4比光還原法所制備的CdS/Au/g-C3N4以及生物分子輔助構(gòu)建的Au@CdS/g-C3N4具有更好的光催化活性及穩(wěn)定性,在環(huán)境光催化領(lǐng)域具有良好的應(yīng)用前景。
[Abstract]:As a visible light-responsive nonmetallic polymer semiconductor material, graphite-phase carbon nitride (G-C _ 3N _ 4) has a broad application prospect in the field of environmental photocatalysis. However, the unmodified g-C3N4 has some defects, such as small range of visible light response, easy recombination of photogenerated electron-hole and low photocatalytic activity of visible light, which is unfavorable for practical application. In this paper, based on noble metal au and semiconductor CdS modified g-C3N4, g-C3N4 matrix composites with high photocatalytic activity were prepared by photoreduction method and biomolecular assistant method respectively. On this basis, the photocatalytic performance was further improved by means of controlling au content and carbon coating. The main contents and results of this paper are as follows: 1) CdS/Au/g-C3N4 composites were prepared by two-step photoreduction method. It is found that there are two kinds of structure in CdS/Au/g-C3N4 composites: 1: CdS-g-C3N4 heterojunction and CdS-Au-g-C3N4 all solid-state Z-type structure. The photocatalytic degradation of Rhodamine B shows that the photocatalytic activity of CDs / Aug-C3N4 is higher than that of Au/g-C3N4 and CdS/g-C3N4, which may be due to the higher efficiency of photoelectron generation and hole separation in the all-solid-state Z-type structure of CdS/Au/g-C3N4. High photocatalytic redox and visible light absorption. 2) Au@CdS/g-C3N4 composites were fabricated in situ by biomolecular cysteine assisted method. The core-shell structure of CdS and au was constructed and loaded on the surface of g-C3N4 by connecting with each other, which avoided the appearance of CdS-g-C3N4 heterojunction and formed the all-solid-state Z-type structure of CdS-Au-g-C3N4 and the structure of Au@CdS core-shell. In the process of photocatalytic degradation of phenol and methyl orange, au @ CdS / g-C _ 3N _ 4 composite showed good photocatalytic activity and stability. The size of Au@CdS is smaller and more evenly distributed on the surface of g-C3N4, resulting in the formation of a single all-solid-state Z-type structure of CdS-Au-g-C3N4, which promotes the separation of photogenerated electrons and holes, and effectively improves the photocatalytic activity of Au@CdS/g-C3N4. The amorphous carbon film on the surface of C/Au@CdS/g-C3N4 composites obtained by hydrothermal carbonization has good adsorption properties, which is beneficial to the enrichment of contaminant molecules on the surface of the composites, and accelerates the photocatalytic degradation of pollutants at the same time. It also accelerates the consumption rate of photogenic oxide species such as holes, superoxide anions and hydroxyl radicals, which effectively inhibits the photocatalytic properties of Au@CdS. On the basis of biomolecular assistance, C/Au@CdS/g-C3N4 obtained by controlling au content and carbon coating has better photocatalytic activity and stability than CdS/Au/g-C3N4 prepared by photoreduction and Au@CdS/g-C3N4 constructed by biomolecules. It has a good application prospect in the field of environmental photocatalysis.
【學(xué)位授予單位】：湖北工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB33;O643.36

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