Europium doped ZnO/SnO2 nanocomposite phosphors were synthesized via room temperature co-precipitation method. In this work structural changes, optical properties and the associated photoluminescence response were inv...Europium doped ZnO/SnO2 nanocomposite phosphors were synthesized via room temperature co-precipitation method. In this work structural changes, optical properties and the associated photoluminescence response were investigated for different compositions of ZnO and SnO2 activated with Eu3＋ ions. The prepared samples were systematically characterized by means of X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, field emission scanning electron microscopy for obtaining the structural information about the prepared materials. Diffuse reflectance （DR） UV-Vis spectrometer and photoluminescence （PL） spectroscopy technique were employed for studying the optical properties of prepared materials. XRD results confirmed the presence of both phases, hexagonal ZnO as well as tetragonal SnO2 simultaneously and further using Debye Scherrer＇s and Hall-Williamson relations, crystallite size were estimated and it was found to be in the range of 8-14 nm. The FTIR studies revealed the presence of different stretching and bending modes of Zn-O and Sn-O with an additional stretching and bending vibration of absorbed water （O-H） molecules. FESEM images suggested that the particle size lied in the range of 50 to 70 nm, which were almost spherical in shapes. A long range multi colour emission from blue to red region was observed for the 320 nm excitation wavelength. The observed emission involved sharp emission due to 5D0→7F1 transition that corresponded to the magnetic dipole transition. The study showed that the Eu3＋ doped nanocomposite was more suitable material than singly Eu3＋ doped ZnO and Eu3＋ doped SnO2 with enhanced opto-eleetronic and luminescence properties and potential applications in display devices.展开更多
Ag/TiO2/freeze-dried graphene nanocomposites have been prepared via a facile one-step solvothermal method for the photocatalytic degradation of Rh B under visible light irradiation. During the solvothermal process, re...Ag/TiO2/freeze-dried graphene nanocomposites have been prepared via a facile one-step solvothermal method for the photocatalytic degradation of Rh B under visible light irradiation. During the solvothermal process, reduction of graphene oxide and loading of Ag/TiO2nanoparticles on graphene sheets were achieved. Investigation of chemical state of products showed that covering of Ag/TiO2surface with higher weight ratio of graphene resulting in that Ag metals in Ag/TiO2were oxidized to Ag2 O in nanocomposite structure after solvothermal process. Degree of photocatalytic activity enhancement strongly depends on the coverage of Ag/TiO2surface by porous graphene. The sample of 1 wt% porous graphene hybridized Ag/TiO2showed the highest photocatalytic activity, which is related to high migration efficiency of photoinduced of electrons and reduction of electron–hole recombination rate due to high electrical conductivity of graphene. Expanding of absorption to visible light region was ascribed to surface plasmon resonance effect of Ag metals and presence of graphene. Investigation of photocatalytic performance of formic acid as a dye-less organic pollutant showed that dye sensitization effect of Rh B molecules during evaluation of photocatalytic performance was negligible.展开更多
Nanocomposites composed of SnO2 and CuO were prepared by hydrothermal method. The microstructures of obtained SnO2-CuO powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electr...Nanocomposites composed of SnO2 and CuO were prepared by hydrothermal method. The microstructures of obtained SnO2-CuO powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption test. The results show that the nanocomposites exhibited coral-like nanostructure, and the average crystalline size of SnO2 was 12 nm. The specific surface area of the four samples, SnO2- 0.2CuO, SnO2-0.5CuO, SnO2-1.0CuO and SnO2-2.0CuO are 72.97, 58.77, 49.72 and 54.95 m2/g, respectively. The gas sensing performance of the four samples to ethanol, formaldehyde and H2S was studied. The sensor of SnOa-0.5CuO exhibited high response to hydrogen sulfide （4173 to 10 ppm H2S, where ppm represent 10-6）, and low response to ethanol and formaldehyde. The good selectivity exhibited that the SnO2-0.5CuO nanocomposite can be a promising candidate for highly sensitive and selective gas-sensing material to H2S.展开更多
Developing anatase/rutile phase-junction in Ti O_(2)to construct Z-scheme system is quite effective to improve its photoelectrochemical activity.In this work,the anatase/rutile phase-junction Ag/Ti O_(2)nanocomposites...Developing anatase/rutile phase-junction in Ti O_(2)to construct Z-scheme system is quite effective to improve its photoelectrochemical activity.In this work,the anatase/rutile phase-junction Ag/Ti O_(2)nanocomposites are developed as photocathodes for hydrogen production.The optimized Ag/Ti O_(2)nanocomposite achieves a high current density of 1.28 m A cm-2,an incident photon-to-current conversion efficiency(IPCE)of 10.8%,an applied bias photon-to-current efficiency(ABPE)of 0.32 at 390 nm and a charge carriers’lifetime up to 2000 s.Such enhancement on photoelectrochemical activity can be attributed to:(ⅰ)the generated Z-scheme system in the anatase/rutile phase-junction Ag/Ti O_(2)photocathode enhances the separation,diffusion and transformation of electron/hole pairs inside the structure,(ⅱ)Ag nanodots modification in the anatase/rutile phases leading to the tuned band gap with enhanced light absorption and(ⅲ)the formed Schottky barrier after Ag nanodots surface modification provides enough electron traps to avoid the recombination of photogenerated electrons and holes.Our results here suggest that developing phase-junction nanocomposite as photocathode will provide a new vision for their enhanced photoelectrochemical generation of hydrogen.展开更多
基金supported by ISM research scholars funding by Government of India
文摘Europium doped ZnO/SnO2 nanocomposite phosphors were synthesized via room temperature co-precipitation method. In this work structural changes, optical properties and the associated photoluminescence response were investigated for different compositions of ZnO and SnO2 activated with Eu3＋ ions. The prepared samples were systematically characterized by means of X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, field emission scanning electron microscopy for obtaining the structural information about the prepared materials. Diffuse reflectance （DR） UV-Vis spectrometer and photoluminescence （PL） spectroscopy technique were employed for studying the optical properties of prepared materials. XRD results confirmed the presence of both phases, hexagonal ZnO as well as tetragonal SnO2 simultaneously and further using Debye Scherrer＇s and Hall-Williamson relations, crystallite size were estimated and it was found to be in the range of 8-14 nm. The FTIR studies revealed the presence of different stretching and bending modes of Zn-O and Sn-O with an additional stretching and bending vibration of absorbed water （O-H） molecules. FESEM images suggested that the particle size lied in the range of 50 to 70 nm, which were almost spherical in shapes. A long range multi colour emission from blue to red region was observed for the 320 nm excitation wavelength. The observed emission involved sharp emission due to 5D0→7F1 transition that corresponded to the magnetic dipole transition. The study showed that the Eu3＋ doped nanocomposite was more suitable material than singly Eu3＋ doped ZnO and Eu3＋ doped SnO2 with enhanced opto-eleetronic and luminescence properties and potential applications in display devices.
文摘Ag/TiO2/freeze-dried graphene nanocomposites have been prepared via a facile one-step solvothermal method for the photocatalytic degradation of Rh B under visible light irradiation. During the solvothermal process, reduction of graphene oxide and loading of Ag/TiO2nanoparticles on graphene sheets were achieved. Investigation of chemical state of products showed that covering of Ag/TiO2surface with higher weight ratio of graphene resulting in that Ag metals in Ag/TiO2were oxidized to Ag2 O in nanocomposite structure after solvothermal process. Degree of photocatalytic activity enhancement strongly depends on the coverage of Ag/TiO2surface by porous graphene. The sample of 1 wt% porous graphene hybridized Ag/TiO2showed the highest photocatalytic activity, which is related to high migration efficiency of photoinduced of electrons and reduction of electron–hole recombination rate due to high electrical conductivity of graphene. Expanding of absorption to visible light region was ascribed to surface plasmon resonance effect of Ag metals and presence of graphene. Investigation of photocatalytic performance of formic acid as a dye-less organic pollutant showed that dye sensitization effect of Rh B molecules during evaluation of photocatalytic performance was negligible.
基金financially supported by the National Natural Science Foundation of China (No. 51072141)the scientific research projects of Education Department of Hubei province (D20141503)the President Foundation of Wuhan Institute of Technology (No. 2014029)
文摘Nanocomposites composed of SnO2 and CuO were prepared by hydrothermal method. The microstructures of obtained SnO2-CuO powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption test. The results show that the nanocomposites exhibited coral-like nanostructure, and the average crystalline size of SnO2 was 12 nm. The specific surface area of the four samples, SnO2- 0.2CuO, SnO2-0.5CuO, SnO2-1.0CuO and SnO2-2.0CuO are 72.97, 58.77, 49.72 and 54.95 m2/g, respectively. The gas sensing performance of the four samples to ethanol, formaldehyde and H2S was studied. The sensor of SnOa-0.5CuO exhibited high response to hydrogen sulfide （4173 to 10 ppm H2S, where ppm represent 10-6）, and low response to ethanol and formaldehyde. The good selectivity exhibited that the SnO2-0.5CuO nanocomposite can be a promising candidate for highly sensitive and selective gas-sensing material to H2S.
基金supported financially by the Academy of Scientific Research and Technology(No.6618,ASRT,Egypt)the National Key R&D Program of China(No.2016YFA0202602),the National Natural Science Foundation of China(Nos.U1663225 and 21805220)+2 种基金the Fundamental Research Funds for the Central Universities(WUT:Nos.2019Ⅲ012GX and 2020Ⅲ002GX)the Hubei Provincial Natural Science Foundation(No.2018CFB242 and 2020CFB416)supported by the State Key Laboratory of Silicate Materials for Architectures and Center for Materials Research and Analysis at Wuhan University of Technology。
文摘Developing anatase/rutile phase-junction in Ti O_(2)to construct Z-scheme system is quite effective to improve its photoelectrochemical activity.In this work,the anatase/rutile phase-junction Ag/Ti O_(2)nanocomposites are developed as photocathodes for hydrogen production.The optimized Ag/Ti O_(2)nanocomposite achieves a high current density of 1.28 m A cm-2,an incident photon-to-current conversion efficiency(IPCE)of 10.8%,an applied bias photon-to-current efficiency(ABPE)of 0.32 at 390 nm and a charge carriers’lifetime up to 2000 s.Such enhancement on photoelectrochemical activity can be attributed to:(ⅰ)the generated Z-scheme system in the anatase/rutile phase-junction Ag/Ti O_(2)photocathode enhances the separation,diffusion and transformation of electron/hole pairs inside the structure,(ⅱ)Ag nanodots modification in the anatase/rutile phases leading to the tuned band gap with enhanced light absorption and(ⅲ)the formed Schottky barrier after Ag nanodots surface modification provides enough electron traps to avoid the recombination of photogenerated electrons and holes.Our results here suggest that developing phase-junction nanocomposite as photocathode will provide a new vision for their enhanced photoelectrochemical generation of hydrogen.
