Facile and fast combustion method was used to synthesize Zn O and Ce-doped Zn O（CZO） nanocrystalline powders photocatalysts with different cerium concentrations（0.5 wt.%–10.0 wt.%） followed by calcination at 700 ...Facile and fast combustion method was used to synthesize Zn O and Ce-doped Zn O（CZO） nanocrystalline powders photocatalysts with different cerium concentrations（0.5 wt.%–10.0 wt.%） followed by calcination at 700 oC for 3 h. The prepared samples were characterized by a variety of characterization techniques such as X-ray diffraction（XRD）, scanning electron microscopy（SEM） combined with energy dispersive X-ray diffraction（EDX）, transmission electron microscopy（TEM）, UV-visible spectroscopy, BET surface area analyser and photoluminescence spectroscopy（PL）, to study the crystal structure, surface morphology, chemical composition and optical properties. It was observed from XRD results that synthesized powders had hexagonal wurtzite structure with the smallest crystallite size about 13 nm. Absorption spectra showed that cerium doping enhanced the light absorption properties towards the visible light region. Photoluminescence spectra for Ce-doped Zn O samples exhibited relatively weak near band edge（NBE） emission peaks as compared to that of pristine Zn O. The photocatalytic activities of the prepared samples were evaluated by photocatalytic degradation of Rhodamine B（Rh B） under UV light and visible light（λ≥420 nm） irradiation. The textile mill effluent containing organic matters was also treated under sunlight using photocatalysis and the reduction in the chemical oxygen demand（COD） of the treated effluent revealed a complete destruction of the organic molecules along with colour removal. The results showed that the CZO photocatalyst doped with 3.0 wt.% cerium exhibited four times enhanced photocatalytic activity compared to pure Zn O. The enhanced photocatalytic activity could be attributed to extended visible light absorption and inhibition of the electron-hole pair＇s recombination.展开更多
Particle size, textural and surface characteristics influence some major technological properties of high siliceous aluminosilicate zeolite and sillicoaluminophosphate （SAPO） microporous materials. A comparative stu...Particle size, textural and surface characteristics influence some major technological properties of high siliceous aluminosilicate zeolite and sillicoaluminophosphate （SAPO） microporous materials. A comparative study was furnished for measuring surface characteristics, particle size and particle size distribution using particle size analyzer （PSA） and scanning electron microscope （SEM）. The PSA is capable of measuring particle diameter in micron range. The results of these techniques for estimation of particle size were compared and correlated statistically. Student t-test and variance ratio test （F-test） methods were performed for the significance of results by the analysis of variance （ANONA） and multiple-range tests. Textural and surface characteristics were evaluated by Brunauer, Emmett ＆ Teller （BET） volumetric technique and v-αs plotting method. The textural results shows that the external surface area and micropore volume of microporous materials were higher than those of the high siliceous zeolites and its zeotype materials.展开更多
基金Project supported by Higher Education Commission(HEC)of Pakistan through IRSIP scholarship program
文摘Facile and fast combustion method was used to synthesize Zn O and Ce-doped Zn O（CZO） nanocrystalline powders photocatalysts with different cerium concentrations（0.5 wt.%–10.0 wt.%） followed by calcination at 700 oC for 3 h. The prepared samples were characterized by a variety of characterization techniques such as X-ray diffraction（XRD）, scanning electron microscopy（SEM） combined with energy dispersive X-ray diffraction（EDX）, transmission electron microscopy（TEM）, UV-visible spectroscopy, BET surface area analyser and photoluminescence spectroscopy（PL）, to study the crystal structure, surface morphology, chemical composition and optical properties. It was observed from XRD results that synthesized powders had hexagonal wurtzite structure with the smallest crystallite size about 13 nm. Absorption spectra showed that cerium doping enhanced the light absorption properties towards the visible light region. Photoluminescence spectra for Ce-doped Zn O samples exhibited relatively weak near band edge（NBE） emission peaks as compared to that of pristine Zn O. The photocatalytic activities of the prepared samples were evaluated by photocatalytic degradation of Rhodamine B（Rh B） under UV light and visible light（λ≥420 nm） irradiation. The textile mill effluent containing organic matters was also treated under sunlight using photocatalysis and the reduction in the chemical oxygen demand（COD） of the treated effluent revealed a complete destruction of the organic molecules along with colour removal. The results showed that the CZO photocatalyst doped with 3.0 wt.% cerium exhibited four times enhanced photocatalytic activity compared to pure Zn O. The enhanced photocatalytic activity could be attributed to extended visible light absorption and inhibition of the electron-hole pair＇s recombination.
文摘Particle size, textural and surface characteristics influence some major technological properties of high siliceous aluminosilicate zeolite and sillicoaluminophosphate （SAPO） microporous materials. A comparative study was furnished for measuring surface characteristics, particle size and particle size distribution using particle size analyzer （PSA） and scanning electron microscope （SEM）. The PSA is capable of measuring particle diameter in micron range. The results of these techniques for estimation of particle size were compared and correlated statistically. Student t-test and variance ratio test （F-test） methods were performed for the significance of results by the analysis of variance （ANONA） and multiple-range tests. Textural and surface characteristics were evaluated by Brunauer, Emmett ＆ Teller （BET） volumetric technique and v-αs plotting method. The textural results shows that the external surface area and micropore volume of microporous materials were higher than those of the high siliceous zeolites and its zeotype materials.
