Cs_(x)WO_(3)/TiO_(2) composites with full-spectrum catalytic activity were prepared by solvothermal reaction.The composites were characterized using X-ray diffraction(XRD)analysis,scanning electron microscopy(SEM),tra...Cs_(x)WO_(3)/TiO_(2) composites with full-spectrum catalytic activity were prepared by solvothermal reaction.The composites were characterized using X-ray diffraction(XRD)analysis,scanning electron microscopy(SEM),transmission electron microscopy(TEM),specific surface area testing,X-ray photoelectron spectroscopy(XPS),and UV-Vis diffuse reflectance spectra(UV-Vis DRS).Cs_(x)WO_(3) and TiO_(2) were uniformly bonded together in the compos-ites.The heterojunction structure was formed.The band gap was reduced from 2.75 to 2.65 eV.The photocatalytic property of Cs_(x)WO_(3)/TiO_(2)was demonstrated by the degradation rates of 20 mg·L^(-1) methylene blue dye,which were 99.7%,91.4%,and 70.7%under irradiation from a 300 W high-pressure mercury lamp,a 500 W xenon lamp,and a 400 W infrared lamp,respectively.After five cycles of photocatalytic degradation,the composite photocatalyst still showed a degradation efficiency of 87.6%.This indicates that Cs_(x)WO_(3)/TiO_(2) has good photocatalytic degradability and cyclic stability.The photocatalytic mechanism of Cs_(x)WO_(3)/TiO_(2)was investigated.The trapping experiments of the active species showed that the main active substances were the empty hole(h+)and hydroxyl radical(·OH).展开更多
文摘应用全光谱测量水体化学需氧量(chemical oxygen demand,COD)、硝酸盐氮(NO_(3)-N)浓度等水环境质量指标容易受水质环境影响,检测模型与特征波长一直是全光谱检测推广关注重点。该文提出一种基于遗传算法-径向基神经网络(genetic algorithm-radial basis function neural network,GA-RBFNN)全光谱水体COD与NO_(3)-N浓度检测方法,鉴于GA搜索能力强、随机性高的特点,对预处理后全光谱吸收数据应用GA进行特征波长选取,以RBFNN神经网络留K法训练过程中平均决定系数作为适应度函数,输出最优特征波长与RBFNN神经网络参数进行部署,从而实现水体COD、NO_(3)-N浓度准确测量。最后,开展GA-RBFNN、偏最小二乘(partial least squares,PLS)、GA-PLS、RBFNN四种模型对160组水样的COD、NO_(3)-N浓度检测实验,结果表明GA-RBFNN模型对COD、NO_(3)-N检测平均决定系数、最大误差分别为0.9964、0.9950和3.9%、4.9%,均优于其他模型,方法具有重要推广价值。
文摘Cs_(x)WO_(3)/TiO_(2) composites with full-spectrum catalytic activity were prepared by solvothermal reaction.The composites were characterized using X-ray diffraction(XRD)analysis,scanning electron microscopy(SEM),transmission electron microscopy(TEM),specific surface area testing,X-ray photoelectron spectroscopy(XPS),and UV-Vis diffuse reflectance spectra(UV-Vis DRS).Cs_(x)WO_(3) and TiO_(2) were uniformly bonded together in the compos-ites.The heterojunction structure was formed.The band gap was reduced from 2.75 to 2.65 eV.The photocatalytic property of Cs_(x)WO_(3)/TiO_(2)was demonstrated by the degradation rates of 20 mg·L^(-1) methylene blue dye,which were 99.7%,91.4%,and 70.7%under irradiation from a 300 W high-pressure mercury lamp,a 500 W xenon lamp,and a 400 W infrared lamp,respectively.After five cycles of photocatalytic degradation,the composite photocatalyst still showed a degradation efficiency of 87.6%.This indicates that Cs_(x)WO_(3)/TiO_(2) has good photocatalytic degradability and cyclic stability.The photocatalytic mechanism of Cs_(x)WO_(3)/TiO_(2)was investigated.The trapping experiments of the active species showed that the main active substances were the empty hole(h+)and hydroxyl radical(·OH).
