纳米赤铁矿电极光电催化特性及苯酚降解活性研究

Photoelectrochemical performance of nano-hematite electrode and photoelectrocatalytic activity toward oxidation of phenol

伴随环境污染问题日益加剧,借助半导体材料实现光能的光电转化在催化及环境领域引起广泛关注。本文借助电化学方法快速高效地合成不同沉积时间纳米赤铁矿薄膜电极。X射线衍射(XRD)、Raman光谱测试表明其成分为赤铁矿物相;原子力显微镜(AFM)观测颗粒尺寸约52.1(±1.48)nm×50.5(±1.49)nm,表面高度起伏分布于70~100 nm,且分布特征符合正态分布规律。紫外可见漫反射吸收谱显示电极可显著吸收350~600 nm波长范围可见光,计算得禁带宽度约2.0~2.1 e V。光电化学实验光电流密度-时间曲线及电流-电压曲线表明电极有良好的可见光光电催化活性,且反应符合Langmuir-Hinshelwood多相反应动力学模型。进一步选取效果较显著的沉积时间10 min电极研究其光电催化降解苯酚活性,0.65 V vs.SCE(饱和甘汞电极)恒电势光照条件下6 h苯酚降解率达62%,拟合一级动力学反应模型可知,反应速率常数k为0.16 h-1(R2=0.996)。综上,本文研究结果显示电化学法简单高效合成的纳米赤铁矿具有良好半导体性能且能够可见光光电催化降解苯酚等有机污染物。

As the problem of environmental pollution has become increasingly aggr avated,the conversion of solar energy catalyzed by semiconductor material has c aused much concern in the field of catalytic and environmental protection.Nano-hematite electrodes with different deposition time were synthesized by electroch emical method more quickly and effectively in this paper.X-ray Diffraction （XRD） and Raman spectroscopy confirmed that the electrode had single phase of hemati te.Morphology information was obtained by Atomic Force Microscope （AFM）.The na no-hematite had a particle size of 52.1（±1.48） nm×50.5（±1.49） nm,and the su rface height was concentrated in the range of 70~100 nm,which was consistent with the normal distribution law.Moreover,the UV-Vis Diffuse Reflectance spectr a illustrated the significant absorption of visible light from 350 nm to 600 nm, and the calculating result of band gap was about 2.0~2.1 eV.In photoelectro ch emical experiments,the photocurrent density-time curve and I-V curves indicated that the electrode had great photoelectrocatalysis activity and the reaction pr ocess accorded with the Langmuir-Hinshelwood kinetics model.Furthermore, 10-minute-deposited hematite electrode was used to investigate the activity of photoelectrocatalytic degradation of phenol.The results showed that degradation rate o f phenol reached 62% after 6 h under a constant potential of 0.65 V versus SCE （Saturated Calomel Electrode） and the constant of reaction rate k was 0.16 h-1 （R2=0.996） when the first-order kinetics reaction model was fitted. It is thus s hown that the electrochemically deposited nano-hematite possesses satisfying con ductive properties and the capability of degrading phenol and other organic poll utions.