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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)(R2>0.996)。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。
With the worsening of environmental pollution, the photoelectric conversion of light energy has drawn wide attention in the field of catalysis and the environment. Birnessite is one of the common manganese minerals on the surface. In this paper, a nano-birnessite electrode was prepared rapidly and efficiently by electrochemical charge control method. X-ray diffraction (XRD) and Raman spectroscopy showed that the phase was single as birnessite. AFM microscopic morphology of the electrode surface showed irregular polygonal lattice-like voids, and the deposition power was 0.5,1.0,1.5 C The birnessite thickness is about 30,200,450 nm respectively. UV-visible diffuse reflectance absorption spectra show that the electrode can absorb visible light with a wavelength of 300-600 nm. The Tauc equation calculates the indirect bandgap of the electrode about 0.8-1.3 eV and the direct band gap of about 2.0-2.3 eV. The Mott-Schottky curve calculates the band potential of about 1.15 V, and the three electrode carrier concentration were 3.26 × 10 ~ (19), 4.63 × 10 ~ (19) and 2.70 × 1020 cm ~ (-3), respectively. Photocurrent density-time curve and linear sweep voltammetry showed that the electrode has a good photoelectrochemical response Evs.SCE = 1.0 V (saturated calomel electrode) constant potential illumination conditions, 150 min 0.5,1.0,1.5 C birnessite The degradation rates of 5 mg / L methyl orange electrode were 66.3%, 70.0% and 67.5%, respectively. The reaction rate constants k were 0.44 h -1, 0.48 h -1, 0.46 h ~ -1) (R2> 0.996). In summary, this study shows that nano birnessite electrode can effectively visible light photo-catalytic degradation of organic pollutants such as methyl orange.