纳米水钠锰矿可见光光电化学响应与甲基橙降解活性

发布时间：2019-01-23 15:40

【摘要】：伴随环境污染问题日益加剧,光能的光电转化在催化及环境领域引起广泛关注。水钠锰矿是地表常见锰矿物之一,本文借助电化学电量控制法快速高效制备了纳米水钠锰矿电极。X射线衍射(XRD)、Raman光谱测试表明物相单一为水钠锰矿;原子力显微镜(AFM)观察电极微观形貌可见表面分布有不规则多边形格子状空隙,测定沉积电量为0.5、1.0、1.5 C水钠锰矿厚度分别约为30、200、450 nm。紫外可见漫反射吸收谱显示电极可显著吸收300~600 nm波长可见光,Tauc方程计算电极间接带隙约0.8~1.3 eV,直接带隙约2.0~2.3 eV,Mott-Schottky曲线计算平带电位约1.15 V,三电极载流子浓度分别为3.26×10~(19)、4.63×10~(19)、2.70×1020 cm~(-3)。光电流密度-时间曲线及线性扫描伏安曲线表明电极有良好光电化学响应活性Evs.SCE=1.0 V(饱和甘汞电极)恒电势光照条件下,150 min后0.5、1.0、1.5 C水钠锰矿电极对5 mg/L甲基橙降解率分别为66.3%,70.0%,67.5%,拟合反应速率常数k分别为0.44 h~(-1)、0.48 h~(-1)、0.46 h~(-1)(R20.996)。综上,本文研究表明纳米水钠锰矿电极能有效可见光光电催化降解甲基橙等有机污染物。
[Abstract]:With the worsening of environmental pollution, photovoltaic conversion of light energy has attracted wide attention in the field of catalysis and environment. Sodium manganite is one of the most common manganese minerals on the surface. Nanocrystalline sodium manganite electrodes have been prepared rapidly and efficiently by means of electrochemical electricity control method. X-ray diffraction (XRD), Raman) spectra show that the phase of the nanocrystalline manganite is a single sodium manganite. Atomic force microscope (AFM) (AFM) was used to observe the microcosmic morphology of electrode with irregular polygonal lattice voids. The thickness of sodium manganite was about 30200450 nm.. UV-Vis diffuse reflectance spectroscopy showed that the electrode could significantly absorb the visible light at the wavelength of 300,600 nm. The indirect band gap of the electrode was calculated by Tauc equation. The indirect band gap of the electrode was about 0.81.3 eV, and the direct band gap was 2.02.3V. the flat band potential of the electrode was estimated to be about 1.15V. The carrier concentrations of three electrodes are 3.26 脳 10 ~ (19), 4.63 脳 10 ~ (19) and 2.70 脳 1020 cm~ (-3), respectively. The photocurrent density-time curve and the linear scanning voltammetry curve show that the electrode has a good photochemical response under the constant potential illumination of Evs.SCE=1.0 V (saturated calomel electrode). After 150 min, the degradation rate of 5 mg/L methyl orange was 66.3- 70.0 and 0.44 h-1, 0.48 h ~ (-1), respectively, and the degradation rate of 5 mg/L methyl orange was 0.44 h ~ (-1) and 0.48 h ~ (-1), respectively, and the corresponding reaction rate constants were 0.44 h ~ (-1) and 0.48 h ~ (-1), respectively. 0.46 h-1 (R20.996). In summary, it is shown that nanocrystalline sodium manganite electrode can effectively photocatalyze the degradation of organic pollutants such as methyl orange by visible light.
【作者单位】：造山带与地壳演化教育部重点实验室矿物环境功能北京市重点实验室北京大学地球与空间科学学院;
【基金】：973计划(2014CB846001) 国家自然科学基金(批准号:41230103;41272003;41402032) 博士后基金(2014M550552)
【分类号】：P579;X703

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