地表“矿物膜”中锐钛矿-β-胡萝卜素协同增强日光响应特性研究

A Study on the Synergistic Effect of Solar Light Response Enhancement of the Anatase and β-carotene in “Mineral Coatings”

为探究"矿物膜"中半导体矿物与光合色素间的日光响应协同作用,对采自安徽潜山市郊的"矿物膜"样品进行了矿物组成和色素组成分析。同步辐射X射线粉末衍射测定表明,样品富含锐钛矿、赤铁矿等半导体矿物;拉曼光谱证实其中存在地表广泛分布的光合色素:β-胡萝卜素。在此基础上开展锐钛矿-β-胡萝卜素协同增强日光响应模拟实验。合成锐钛矿电极并对其进行系统的矿物学表征,紫外-可见漫反射吸收谱计算其禁带宽度约为3.07 eV;莫特-肖特基计算得到的平带电位约为-0.16 V,载流子浓度约为3.25×1026 cm-3;光电化学测试结果显示其具有一定可见光光电转化能力。经β-胡萝卜素敏化处理后,锐钛矿电极平均光电流密度提升了400%,在425~550 nm间光吸收值提高,该波段位于日光辐射能量集中的波长范围内,且与β-胡萝卜素吸收范围吻合,表明二者间存在日光吸收及光电响应协同增强作用。

In order to explore the synergistic effect of solar light response enhancement of semiconducting minerals and photosynthetic pigments in "mineral coating" system, the mineral components and pigment compositions of "mineral coating" samples collected from suburb of Qianshan City in Anhui Province of China have been analyzed by using the synchrotron radiation X-ray powder diffraction and Raman spectroscopy methods in this paper. The results show that those "mineral coating" samples are rich in semiconducting minerals such as anatase and hematite. Meanwhile, β-carotene, a widely distributed photosynthetic pigment on the earth’s surface, was also detected. Then a simulation experiment for studying the synergistic effect of solar light response enhancement of anatase and β-carotene has been carried out on the basis of above study. The synthesized anatase electrodes were systematic mineralogically characterized. An allowed band gap of 3.07 eV was extrapolated by using the UV-Vis diffuse reflection spectroscopy. The flat band potential was-0.16 V and the carrier concentration was 3.25×1026 cm-3 as evaluated by using the Mott-Schottky analysis. Moreover, limited photoelectric conversion capability of the anatase under visible light was available based on the photoelectrochemical tests. After the sensitizing treatment by using β-carotene, the average photocurrent density of the sensitized anatase electrode was increased significantly by 400%. Moreover, the absorbance of the sensitized anatase electrode was improved for light with wavelengths varying from 425 nm to 550 nm, within the range of concentrated solar radiation which is consistent with that of the β-carotene absorption. These confirm that there is synergistic effect of the solar light response enhancement between anatase and β-carotene.