【摘要】：針對(duì)目前日益嚴(yán)峻的水污染問題,半導(dǎo)體光催化技術(shù)是一種有效的解決方法。通過半導(dǎo)體光催化劑在太陽(yáng)光照射下對(duì)水中有機(jī)污染物的降解,達(dá)到凈化水的目的。在眾多半導(dǎo)體材料中,石墨相氮化碳(g-C_3N_4)由于具有無(wú)毒、合適的帶隙和優(yōu)異的穩(wěn)定性而被廣泛研究。但是純的g-C_3N_4仍存在比表面積較小和光生載流子復(fù)合速率較高等不足,導(dǎo)致其光催化降解性能較低,影響實(shí)際應(yīng)用。為此,本文以g-C_3N_4為研究對(duì)象,通過形貌調(diào)控和物理復(fù)合等手段對(duì)其進(jìn)行改性和修飾以提高光催化性能。重點(diǎn)研究g-C_3N_4納米片、Ag/g-C_3N_4復(fù)合材料和Ag/g-C_3N_4/還原氧化石墨烯(Ag/g-C_3N_4/rGO)三維氣凝膠光催化劑的可控制備方法,通過對(duì)亞甲基藍(lán)(MB)的降解,研究光催化劑的可見光催化性能,并揭示材料結(jié)構(gòu)與性能之間的關(guān)系。具體研究?jī)?nèi)容及結(jié)論如下:(1)采用熱氧化剝離、液相剝離和鹽酸輔助水熱剝離制備g-C_3N_4納米片光催化劑(分別標(biāo)記為T-g-C_3N_4、L-g-C_3N_4和H-g-C_3N_4)�？疾烊N剝離方法對(duì)g-C_3N_4納米片微觀結(jié)構(gòu)和光催化性能的影響。結(jié)合SEM、TEM和AFM的結(jié)果與分析可知,T-g-C_3N_4的片層最厚,而L-g-C_3N_4和H-g-C_3N_4的片層較薄。根據(jù)氮?dú)馕矫摳椒治?T-g-C_3N_4具有最大的比表面積,其余依次是H-g-C_3N_4、L-g-C_3N_4和塊體g-C_3N_4。比表面積的大小直接影響光催化活性,T-g-C_3N_4、L-g-C_3N_4和H-g-C_3N_4在可見光照射60 min內(nèi)對(duì)MB的降解率分別為84%、79%和76%,優(yōu)于塊體g-C_3N_4。但由于T-g-C_3N_4片層較厚,L-g-C_3N_4產(chǎn)率較低,均不適用于后期的改性研究。而H-g-C_3N_4片層較薄和產(chǎn)率較高,可作為后期改性對(duì)象。(2)貴金屬Ag具有局域等離子體共振效應(yīng),能夠有效吸收可見光,提高光催化性能。以H-g-C_3N_4納米片為基底,通過自組裝工藝制備不同納米銀(Ag NPs)負(fù)載量的Ag/g-C_3N_4光催化劑,詳細(xì)考察Ag負(fù)載量對(duì)其光催化性能的影響。結(jié)果表明,Ag NPs的引入,使得復(fù)合材料對(duì)可見光的吸收增強(qiáng),且能夠有效分離光生載流子,從而得到增強(qiáng)的光催化活性。其中,Ag/g-C_3N_4(6:5)復(fù)合材料具有最優(yōu)的光催化活性,60 min內(nèi)MB的降解率達(dá)到99%,且具有良好的光穩(wěn)定性。(3)石墨烯具有大的比表面積和優(yōu)異的電子遷移能力,因此常用石墨烯為光催化劑的載體來(lái)進(jìn)一步提高材料的光催化性能。向Ag/g-C_3N_4復(fù)合材料中引入氧化石墨烯(GO),并通過化學(xué)還原-凝膠化反應(yīng)制備得到Ag/g-C_3N_4/rGO三維氣凝膠。結(jié)果表明,該氣凝膠具有典型的三維網(wǎng)絡(luò)交聯(lián)結(jié)構(gòu)。與Ag/g-C_3N_4復(fù)合材料相比,氣凝膠禁帶寬度降低至2.3 eV,比表面積增大至139.509 m2/g,具有增強(qiáng)的可見光吸收能力、良好的吸附性能和光催化降解性能。吸附平衡后降解30min,復(fù)合材料對(duì)MB的降解率達(dá)到98%,且具有良好的循環(huán)穩(wěn)定性。與復(fù)合粉體相比,三維氣凝膠具有易回收的優(yōu)點(diǎn),因此具有很好的實(shí)際應(yīng)用前景。
[Abstract]:Semiconductor photocatalysis is an effective solution to the increasingly serious problem of water pollution. The degradation of organic pollutants in water by semiconductor photocatalyst under solar irradiation can achieve the purpose of purifying water. Among many semiconductor materials, graphite phase carbon nitride (g-C_3N_4) has been widely studied because of its non-toxic, suitable band gap and excellent stability. However, the pure g-C_3N_4 still has some shortcomings, such as small specific surface area and high photogenerated carrier recombination rate, which leads to the low photocatalytic degradation performance, which affects the practical application. In this paper, g-C_3N_4 was modified and modified by means of morphology regulation and physical recombination to improve its photocatalytic performance. The controllable preparation methods of g-C_3N_4 nanoparticles, Ag/g-C_3N_4 composites and Ag/g-C_3N_4/ reduction graphene oxide (Ag/g-C_3N_4/rGO) three-dimensional gas gel photocatalysts were studied. Through the degradation of methylene blue (MB), the visible light catalytic performance of photocatalysts was studied, and the relationship between the structure and properties of the materials was revealed. The specific research contents and conclusions are as follows: (1) g-C_3N_4 nanoparticles photocatalysts were prepared by thermal oxidation stripping, liquid phase stripping and hydrochloric acid assisted hydrothermal stripping, respectively. (L-g-C_3N_4 and H-g-C_3N_4). The effects of three stripping methods on the microstructure and photocatalysis of g-C_3N_4 nanoparticles were investigated. Combined with the results and analysis of SEM,TEM and AFM, it can be seen that the lamellae of T-g-C_3N_4 is the thickest, while that of L-g-C_3N_4 and H-g-C_3N_4 is thinner. According to the adsorption and desorption analysis of nitrogen, T-g-C_3N_4 has the largest specific surface area, the rest are H 鈮，

本文編號(hào)：2481714