本文關(guān)鍵詞： Bi_2WO_6 溶膠-凝膠法 摻雜 復(fù)合 光催化　出處：《廣西大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：近年來光催化氧化技術(shù)作為一種新興的水污染處理技術(shù)已經(jīng)成為學(xué)者們的研究熱點。其中,具有類鈣鈦礦層狀結(jié)構(gòu)的Bi2WO6引起了人們的廣泛關(guān)注。Bi2WO6帶隙約為2.7eV左右,能夠被可見光激發(fā),能比較好地利用太陽光。同時,Bi2WO6是一種環(huán)境友好型的可見光催化材料,不存在光腐蝕的現(xiàn)象,光穩(wěn)定性良好。研究和開發(fā)Bi2WO6系列光催化材料,在凈化環(huán)境和開發(fā)新材料等領(lǐng)域都具有潛在的意義。本文通過溶膠-凝膠法、水熱法和溶劑熱法,采用金屬摻雜、半導(dǎo)體復(fù)合等改性手段,分別制備出了Bi2WO6?Eu/Bi2WO6/Bi2O2CO3/Bi3.84W0.16O6.24三種鎢酸鉍光催化材料。采用XRD、SEM、DRS、EDS、XPS等技術(shù)對所制備樣品的結(jié)構(gòu)、形貌、光吸收性能進(jìn)行了表征,并通過在可見光下對羅丹明B(RhB)溶液的降解程度來測定所有樣品的光催化活性,獲得了光催化性能良好的改性鎢酸鉍。具體研究內(nèi)容及結(jié)果如下：(1)以檸檬酸(CA)作為絡(luò)合劑,采用溶膠-凝膠法,在CA與金屬離子摩爾比為3：1、分散劑為PEG4000、前驅(qū)液的pH值為1時,于450℃煅燒3h,制備出了微納米結(jié)構(gòu)的Bi2WO6材料。樣品為斜方晶系結(jié)構(gòu),顆粒約為50nm。在可見光照射60min后,樣品對RhB溶液的降解率達(dá)到了87.9%,表現(xiàn)出良好的光催化性能。(2)采用水熱法,在水熱溫度160℃、水熱時間16h、前驅(qū)液的pH值為1、Eu摻雜量為5%的優(yōu)化條件下合成了Eu/Bi2WO6納米材料。在可見光照1h后,Eu/Bi2WO6對RhB降解率達(dá)到了94.2%,優(yōu)于純相Bi2WO6的75.4%。Bi2WO6摻雜Eu后,吸收波長邊緣發(fā)生了紅移,促進(jìn)了樣品對可見光的吸收。隨著Eu摻雜量的增加,樣品發(fā)生了形貌演變,由二維片狀結(jié)構(gòu)轉(zhuǎn)化為三維花球結(jié)構(gòu)最后變成塊狀晶粒。結(jié)合樣品的結(jié)構(gòu)及其光催化性能的分析,可以推斷出,光催化效率明顯提高是因為三維花球結(jié)構(gòu)中超薄的納米片之間開放的空間,為RhB提供了運輸?shù)耐ǖ篮蛷姶蟮膬Υ鎴鏊?3)采用溶劑熱法,以乙二醇作溶劑,Bi3+和W6+的摩爾比為2：1,在反應(yīng)時間為4h、反應(yīng)溫度為160℃、前驅(qū)液的pH值為11的條件下,得到了Bi2O2CO3/Bi3.84W0.16O6.24復(fù)合催化劑�？梢姽庹�15min后,對RhB的降解率已達(dá)到92%。樣品顆粒尺寸約10nm,明顯小于水熱法得到的Bi2WO6花球。樣品的光吸收波長邊緣紅移,帶隙變窄,對可見光吸收增強。根據(jù)Mulliken電負(fù)性理論,可以推斷Bi3.84W0.16O6.24與Bi2O2CO3復(fù)合后,光生電子和空穴分別富集在Bi2O2CO3的導(dǎo)帶與Bi3.84W0.i6O6.24的價帶上,很大程度上降低了光生載流子的復(fù)合率,從而提高樣品的光催化效率。
[Abstract]:In recent years, photocatalytic oxidation technology as a new water pollution treatment technology has become a research hotspot of scholars. Bi2WO6 with perovskite-like layered structure has attracted much attention. The band gap of Bi2WO6 is about 2.7 EV, which can be excited by visible light and make good use of solar light. Bi2WO6 is a kind of environment-friendly visible light catalytic material. There is no photocorrosion phenomenon and the light stability is good. The research and development of Bi2WO6 series photocatalytic materials. In this paper, sol-gel method, hydrothermal method and solvothermal method, metal doping, semiconductor composite and other modification methods are used. Bi2WO6? Three kinds of bismuth tungstate photocatalytic materials were used. The structure, morphology and light absorption properties of the prepared samples were characterized by XPS and the photocatalytic activity of all the samples was determined by the degradation degree of Rhodamine XPS solution under visible light. The modified bismuth tungstate with good photocatalytic activity was obtained. The specific research contents and results are as follows: 1) with citric acid as the complexing agent, the sol-gel method is used. When the molar ratio of CA to metal ion is 3: 1, the dispersant is PEG4000, the pH value of the precursor is 1:00 and calcined at 450 鈩，

本文編號：1486286