| 王辉,李士君,王梅,裴彦博,胡绍争.载银g-C3N4(Ⅰ)/g-C3N4(Ⅱ)同素异质结催化剂的制备及光催化固氮产氨性能[J].材料导报,2018,32(20):3496-3503 |
| 载银g-C3N4(Ⅰ)/g-C3N4(Ⅱ)同素异质结催化剂的制备及光催化固氮产氨性能 |
| Ag-loaded g-C3N4(Ⅰ)/g-C3N4(Ⅱ) Isotype Heterojunction Catalysts with an Application to Photocatalytic N2 Fixation |
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| DOI：10.11896/j.issn.1005-023X.2018.20.002 |
| 中文关键词: 石墨相氮化碳(g-C3N4) 银负载 贵金属 同素异质结 光催化固氮 |
| 英文关键词: graphitic carbon nitride (g-C3N4), silver loading, noble metal, isotype heterojunction, N2 photofixation |
| 基金项目:辽宁省教育厅一般项目(L2014145)；辽宁省自然科学基金(201602467) |
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| 中文摘要: |
| Ag作为助催化剂能够促进光电子的迁移,在光催化分解水制氢气、CO2还原、重金属离子还原等反应中应用颇多,然而,到目前为止未见将Ag单质作为助催化剂用于光催化固氮产氨反应的报道。本工作制备了负载单质Ag的g-C3N4(Ⅰ)/g-C3N4(Ⅱ)同素异质结催化剂,并考察了其光催化固氮产氨的性能。采用X射线衍射(XRD)、透射电镜(TEM)、紫外可见光谱(UV-Vis)、X射线光电子能谱(XPS)、拉曼光谱(Raman)、荧光光谱(PL)、电化学阻抗谱(EIS)、光电流分析等手段对制备的催化剂进行了表征。结果表明,Ag以单质态存在于催化剂表面。所担载的Ag的等离子体效应一方面促进了催化剂对可见光的吸收,使反应体系能产生更多的光生电子-空穴对；另一方面使得光生电子能够在g-C3N4与Ag单质间迁移,提高了催化剂的电子-空穴分离效率。负载Ag后g-C3N4(Ⅰ)/g-C3N4(Ⅱ)同素异质结催化剂的铵离子产生速率为1.36 mg·L-1·h-1·g-1cat,相比未负载Ag时(0.59 mg·L-1·h-1·g-1cat)大幅提高,与Pt负载催化剂相当,并且是由单纯三聚氰胺和尿素制备的g-C3N4的4.9倍和3.4倍。除固氮反应外,制备的载银g-C3N4(Ⅰ)/g-C3N4(Ⅱ)同素异质结催化剂在光催化还原氧气制取双氧水的反应中也表现出优良的催化性能。 |
| 英文摘要: |
| As a cocatalyst, silver can enhance the photoelectrons migration and has found wide application in a variety of photocatalytic reduction reactions such as water splitting hydrogen generation, CO2 reduction, heavy metal ion reduction, etc. However, to the best of our knowledge, no unconcealed work has concerned N2 photofixation by using Ag-loaded catalysts. Our present work aimed to prepare a series of Ag-loaded g-C3N4(Ⅰ)/g-C3N4(Ⅱ) isotype heterojunction catalysts differing in Ag content (Ag(x%)-CN, x=0.5,1,2,4) and estimate their N2 photofixation performance. The means of XRD, TEM, UV-Vis, XPS, Raman, PL, EIS and photocurrent response were involved in the characterization. Our experiment confirmed the existence of silver on the catalyst surface as metal state, and revealed the acting mechanism of the loaded silver cocatalyst:the plasma effect of silver promotes the visible-light absorption so that the reaction system can produce more photogenerated electron-hole pairs, and on the other hand, the photoelectrons migration between g-C3N4 and Ag improves the electron-hole separation efficiency of the composite catalyst. The NH4+ ge-neration rate of the Ag-loaded g-C3N4(Ⅰ)/g-C3N4(Ⅱ) isotype heterojunction composite catalyst was determined to be 1.36 mg·L-1·h-1·g-1cat with a dramatical increment compared to that of g-C3N4(Ⅰ)/g-C3N4(Ⅱ) without silver-loading (MU-CN,0.59 mg·L-1·h-1·g-1cat). This catalytic performance is equivalent to the Pt-loaded catalysts, and moreover, 4.9 or 3.4 times higher than g-C3N4prepared by exclusively using melamine or urea. In addition to nitrogen fixation, the Ag-loaded g-C3N4(Ⅰ)/g-C3N4(Ⅱ) isotype heterojunction catalysts also exhibited excellent catalytic performance in the reaction of photocatalytic reduction of oxygen to hydrogen peroxide. |
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