Fe对NaNbO_3的晶格掺杂和同步异质结改性及其光催化性能  

Doping and Heterojunctional Cooperation of NaNbO_3 by Fe and Their Photocatalytic Properties

作　　者：崔素珍 杨汉培[1] 孙慧华 聂坤[1] 吴俊明[1] Cui Suzhen Yang Hanpei Sun Huihua Nie Kun Wu Junming(Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098)

机构地区：[1]河海大学浅水湖泊综合治理与资源开发教育部重点实验室河海大学环境学院,南京210098

出　　处：《化学学报》2016年第12期995-1002,共8页Acta Chimica Sinica

基　　金：国家重大科学仪器设备开发专项基金(No.2014YQ060773);江苏省高校优势学科建设工程项目资助~~

摘　　要：运用溶剂热法及继之的高温晶化法制备钙钛矿结构NaNbO_3,并在此基础上同步获得了NaNbO_3晶格内Fe^(3+)的掺杂和NaNbO_3晶格外α-Fe_2O_3的异质结复合.观察到了同步改性NaNbO_3对水体罗丹明B(RhB)光催化降解效率的显著提升,最适Fe含量的改性NaNbO_3对罗丹明B 1 h内的降解率可达95%,表观一级动力学速率常数为改性前NaNbO_3的近7倍.运用X射线衍射(XRD)、扫描电子显微(SEM)、X光电子能谱(XPS)、光致发光(PL)光谱、低温N2吸附-脱附(BET法),电子自旋共振光谱(ESR),紫外-可见漫反射光谱(DRS)及光致电流检测等表征和测量探明改性体系的组成及结构,并表明Fe^(3+)对Nb5+的掺杂取代可通过杂质能级形成、电子和空穴捕获以及溶氧吸附的促进从而有利于对罗丹明B的光催化降解;适量α-Fe_2O_3晶格外复合改性NaNbO_3可通过NaNbO_3与α-Fe_2O_3异质结间电子的跃迁和流动提高复合催化剂的光量子效率.Fe对NaNbO_3晶格内外改性促活的实质可能在于光生载流子迁移的促进和对其复合的抑制.The perovskite-type NaNbO_3 were prepared through a solvothermal process under a moderate condition followed by calcinations at high temperature. The Fe^（3＋）-doping inside the NaNbO_3 lattice and the heterojunctions between α-Fe_2O_3 and NaNbO_3 were acquired synchronously in a similar process by treating NaNbO_3 with ferric nitrates. The photocatalytic activity of catalysts was evaluated from the photodegradation of Rhodamine B（Rh B） in aqueous solution under UV light irradiation and the significant enhancement of degradation rate of aqueous Rh B on modified NaNbO_3 was observed, with the degradation ratio of Rh B reached as high as 95% within 1 h, and the quasi-first-grade rate constant of the Rh B degradation reaction over the modified NaNbO_3 reached almost 7 times of the pristine one under the experimental conditions. Characterizations by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, X-ray photoelectron spectroscopy（XPS）, UV-vis diffuse reflectance spectrophotometry（DRS）, adsorption-desorption of N2 at low temperature（BET calculation）, photoluminescence spectroscopy（PL）, electron spin resonance spectroscopy（ESR） and photocurrent measurement were performed. The compositions and structures of the as-prepared raw and modified catalysts were carefully identified. It is found that the optimal mass fraction of Fe in modified catalysts is around 2.5%, with about 30% of it exists as Fe^（3＋） inside the lattice of NaNbO_3 and the remainder as α-Fe_2O_3 outside the NaNbO_3 lattice. The results of characterizations or measurements suggest that a moderate Nb5＋ in NaNbO_3 can be substituted by Fe^（3＋） while the perovskite-type structure of NaNbO_3 remains unchanging. The moderate Fe-doping into the lattice of NaNbO_3 improved the photocatalytic performance of NaNbO_3 by the donor level of impurities, charge capturing and adsorption of dissolved oxygen. A fitting amount of α-Fe_2O_3 cooperates harmoniously with NaNbO_3 in degradation of Rh B by enhancing t

关 键 词：铌酸钠 铁改性 光催化 罗丹明B 促活机制 

分 类 号：O643.36[理学—物理化学]