氢气还原处理对天然金红石可见光吸收的影响机制  

Effects of Hydrogen Heat Treatment on the Visible Light Absorption of Natural Rutile

作　　者：罗泽敏[1] 李艳[1] 鲁安怀[1] 吴婧[1] 秦善[1] 王长秋[1] 

机构地区：[1]造山带与地壳演化教育部重点实验室,北京大学地球与空间学院,北京100871

出　　处：《矿物学报》2011年第4期634-640,共7页Acta Mineralogica Sinica

基　　金：国家重点基础研究发展计划(973)资助项目(2007CB825602)

摘　　要：天然半导体矿物金红石因结构中含有类质同象替代杂质元素V和Fe,具有一定的可见光吸收和光催化活性。为改善金红石的日光光催化性能,在H2还原气氛下,对天然金红石粉末进行500～900℃不同温度的热处理改性研究。紫外-可见漫反射吸收光谱(UV-Vis diffuse reflectance absorption spectra)表明H2还原处理显著改善了金红石在可见光区460～750 nm波段的光吸收,其中900℃处理样品的光吸收提升最为明显。电子顺磁共振(EPR)和X射线光电子能谱(XPS)测试表明,随着还原温度升高,杂质元素V和Fe从高价态(V5+,Fe3+)向较低的价态(V4+,V3+,Fe2+)转化,同时金红石表面的化学吸附水含量也有所增加。本文认为H2还原热处理引起的过渡金属元素价态的改变,尤其是较低氧化态V离子(V4+和V3+)的形成,可能是导致金红石样品可见光吸收显著增加的主要原因。Natural semiconductor mineral rutile-TiO2,containing the main substituting metal ions of vanadium and iron,has potential capability on optical absorption and photocatalytic activity under sunlight.To further enhance its optical absorption,the rutile powder was modified by using hydrogen heat treatment in the temperatures ranging from 500 ℃ to 900 ℃.The Ultra violet-visible（UV-Vis） absorption spectra showed that the visible light absorption of rutile sample in the wavelength from 460 to 750 nm was significantly enhanced,with the biggest increment in sample treated at 900 ℃.Analysis with Electronic Paramagnetic Resonance（EPR） and X-ray Photoelectron Spectroscopy（XPS） indicated that hydrogen heat treatments induced transformation from V5＋ to V4＋ and V3＋,as well as from Fe3＋ to Fe2＋ in rutile samples,and the atom percentages of chemical absorbed water was gradually increased with increasing temperature.Changes of transition metals,especially the formation of V4＋ and V3＋,were regarded as the main reason for the substantial improved optical absorption in this work.

关 键 词：天然金红石 氢气还原 可见光吸收 电子顺磁共振 

分 类 号：P574[天文地球—矿物学] P578.4[天文地球—地质学]