This paper adopted the hydrothermal method to prepare tungsten oxide(WO_(3))nanorod films and studied the effects of precursor solution concentration(0.02,0.03,0.06 mol/L peroxytungstic acid)and annealing temperature(...This paper adopted the hydrothermal method to prepare tungsten oxide(WO_(3))nanorod films and studied the effects of precursor solution concentration(0.02,0.03,0.06 mol/L peroxytungstic acid)and annealing temperature(200,300,400℃)on their electrochromic properties.The microstructure characterization of WO_(3) films were performed using scanning electron microscope(SEM),X-ray diffraction(XRD),and transmission electron microscope(TEM),and their electrochromic properties were tested by combining an electrochemical workstation with an ultraviolet-visible spectrophotometer.The results showed that the precursor solution concentration directly affected the thickness(290,560,990 nm)and microstructure of WO_(3) films,significantly impacting their electrochromic properties.However,the annealing temperature had a negligible effect.As the precursor solution concentration increased,the optical modulation of WO_(3) films gradually decreased,reaching 51.1%,43.8%,and 35.1%,respectively.The switching time first increased and then stabilized,with coloring times of 7.3,7.7,and 7.7 s,respectively,and bleaching times of 3.8,6.5,and 6.5 s,respectively.The coloration efficiency gradually increased but the increase was relatively small,reaching 41.8,44.4,and 44.8 cm^(2)/C,respectively.Moreover,the cycling stability of WO_(3) films was poor,with the ratios of the final value of optical modulation to the initial value 0.33,0.26,and 0.34,respectively.Additionally,there were bigger differences in the bleached state transmittance,while the colored state transmittance showed smaller variations.However,the former has better cycling stability than the latter.In summary,to obtain better electrochromic properties,the thickness of WO_(3) films should not exceed 290 nm.展开更多
Amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))thin films were prepared on flexible polyimide,rigid quartz glass,and Si substrates via radio frequency magnetron sputtering at room temperature.The effect of oxygen/Ar flow rate ra...Amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))thin films were prepared on flexible polyimide,rigid quartz glass,and Si substrates via radio frequency magnetron sputtering at room temperature.The effect of oxygen/Ar flow rate ratio on the structure,optical property,surface morphology,and chemical bonding properties of the a-Ga_(2)O_(3) films was investigated.Results show that the average optical transmittance of the a-Ga_(2)O_(3) films is over 80%within the wavelength range of 300-2000 nm.The extracted optical band gap of the a-Ga_(2)O_(3) films is increased from 4.97 eV to 5.13 eV with the increase in O_(2)/Ar flow rate ratio from 0 to 0.25,due to the decrease in concentration of oxygen vacancy defects in the film.Furthermore,the optical refractive index and surface roughness of the a-Ga_(2)O_(3) films are optimized when the O_(2)/Ar flow rate ratio reaches 0.25.X-ray photoelectron spectroscopy analysis also shows that the proportion of oxygen vacancies(VO)and Ga-O chemical bonds in the O 1s peak is gradually decreased with the increase in O_(2)/Ar flow rate ratio from 0 to 0.25,proving that increasing the O_(2)/Ar flow rate ratio during film growth can reduce the concentration of oxygen vacancy defects in a-Ga_(2)O_(3) films.In this case,a-Ga_(2)O_(3) with optimal properties can be obtained.This work provides a research basis for high-performance flexible and rigid deep ultraviolet solar-blind detection devices based on a-Ga_(2)O_(3) films.展开更多
As essential electrochromic（EC） materials are related to energy savings in fenestration technology,tungsten oxide（WO3） films have been intensively studied recently.In order to achieve better understanding of the m...As essential electrochromic（EC） materials are related to energy savings in fenestration technology,tungsten oxide（WO3） films have been intensively studied recently.In order to achieve better understanding of the mechanism of EC properties,and thus facilitate optimization of device performance,clarification of the correlation between cation storage and transfer properties and the coloration performance is needed.In this study,transparent polycrystalline and amorphous WO3 thin films were deposited on SnO2：F-coated glass substrates by the pulsed laser deposition technique.Investigation into optical transmittance in a wavelength range of 400-800 nm measured at a current density of 130 μA·cm-2 with the applied potential ranging from 3.2 to 2.2 V indicates that polycrystalline films have a larger optical modulation of ～ 30% at 600 nm and a larger coloration switch time of 95 s in the whole wavelength range compared with amorphous films（～ 24% and 50 s）.Meanwhile,under the same conditions,polycrystalline films show a larger lithium storage capacity corresponding to a Li/W ratio of 0.5,a smaller lithium diffusion coefficient（2×10-12cm2·s-1 for Li/W=0.24） compared with the amorphous ones,which have a Li/W ratio of 0.29 and a coefficient of ～2.5×10-11cm2·s-1 as Li/W=0.24.These results demonstrate that the large optical modulation relates to the large lithium storage capacity,and the fast coloration transition is associated with fast lithium diffusion.展开更多
A novel WO3-x/TiO2 film as photoanode was synthesized for photoelectrocatalytic（PEC） reduction of CO2 into formic acid（HCOOH）. The films prepared by doctor blade method were characterized with X-ray diffractometer...A novel WO3-x/TiO2 film as photoanode was synthesized for photoelectrocatalytic（PEC） reduction of CO2 into formic acid（HCOOH）. The films prepared by doctor blade method were characterized with X-ray diffractometer（XRD）, scanning electron microscope（SEM） and transmission electron microscope（TEM）. The existence of oxygen vacancies in the WO3-x was confirmed with an X-ray photoelectron spectroscopy（XPS）, and the accurate oxygen index was determined by a modified potentiometric titrimetry method. After 3h of photoelectrocatalytic reduction, the formic acid yield of the WO3-x/TiO2 film is 872 nmol/cm^2, which is 1.83 times that of the WO3/TiO2 film. The results of PEC performance demonstrate that the introduction of WO3-x nanoparticles can improve the charge transfer performance so as to enhance the performance of PEC reduction of CO2 into formic acid.展开更多
La0.72Ca0.28MnO3 thin films were deposited on untilted and 15° tilted LaAlO_3 （100） single crystalline substrates by pulsed laser deposition. The polycrystalline targets used in the deposition process were synt...La0.72Ca0.28MnO3 thin films were deposited on untilted and 15° tilted LaAlO_3 （100） single crystalline substrates by pulsed laser deposition. The polycrystalline targets used in the deposition process were synthesized by sol-gel and coprecipitation methods, respectively. The structure, electrical transport properties and surface morphology of the targets and films were studied. It is found that, compared with coprecipitation method, the sol-gel target has more homogeneous components and larger density and grain size, thus the higher insulator-metal transition temperature and larger temperature coefficient of resistivity. The thin film prepared by sol-gel target has a uniform grain size and higher quality. The metal-insulator transition temperature is higher and the laser induced voltage signal is larger. Preparing the target by sol-gel method can largely improve the properties of corresponding thin films in pulsed laser deposition process.展开更多
基金the National Natural Science Foundation of China(No.52272009)the Henan Provincial Science and Technology Research Project(No.242102230151)+1 种基金the Henan Provincial University Science and Technology Innovation Team(No.25IRTSTHN009)the Key Scientific Research Projects of Colleges and Universities in Henan Province(Nos.24B560021,25B560020,25B560023)。
文摘This paper adopted the hydrothermal method to prepare tungsten oxide(WO_(3))nanorod films and studied the effects of precursor solution concentration(0.02,0.03,0.06 mol/L peroxytungstic acid)and annealing temperature(200,300,400℃)on their electrochromic properties.The microstructure characterization of WO_(3) films were performed using scanning electron microscope(SEM),X-ray diffraction(XRD),and transmission electron microscope(TEM),and their electrochromic properties were tested by combining an electrochemical workstation with an ultraviolet-visible spectrophotometer.The results showed that the precursor solution concentration directly affected the thickness(290,560,990 nm)and microstructure of WO_(3) films,significantly impacting their electrochromic properties.However,the annealing temperature had a negligible effect.As the precursor solution concentration increased,the optical modulation of WO_(3) films gradually decreased,reaching 51.1%,43.8%,and 35.1%,respectively.The switching time first increased and then stabilized,with coloring times of 7.3,7.7,and 7.7 s,respectively,and bleaching times of 3.8,6.5,and 6.5 s,respectively.The coloration efficiency gradually increased but the increase was relatively small,reaching 41.8,44.4,and 44.8 cm^(2)/C,respectively.Moreover,the cycling stability of WO_(3) films was poor,with the ratios of the final value of optical modulation to the initial value 0.33,0.26,and 0.34,respectively.Additionally,there were bigger differences in the bleached state transmittance,while the colored state transmittance showed smaller variations.However,the former has better cycling stability than the latter.In summary,to obtain better electrochromic properties,the thickness of WO_(3) films should not exceed 290 nm.
基金Research Project of Shenzhen Science and Technology Innovation Committee(JCYJ20180306170801080)。
文摘Amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))thin films were prepared on flexible polyimide,rigid quartz glass,and Si substrates via radio frequency magnetron sputtering at room temperature.The effect of oxygen/Ar flow rate ratio on the structure,optical property,surface morphology,and chemical bonding properties of the a-Ga_(2)O_(3) films was investigated.Results show that the average optical transmittance of the a-Ga_(2)O_(3) films is over 80%within the wavelength range of 300-2000 nm.The extracted optical band gap of the a-Ga_(2)O_(3) films is increased from 4.97 eV to 5.13 eV with the increase in O_(2)/Ar flow rate ratio from 0 to 0.25,due to the decrease in concentration of oxygen vacancy defects in the film.Furthermore,the optical refractive index and surface roughness of the a-Ga_(2)O_(3) films are optimized when the O_(2)/Ar flow rate ratio reaches 0.25.X-ray photoelectron spectroscopy analysis also shows that the proportion of oxygen vacancies(VO)and Ga-O chemical bonds in the O 1s peak is gradually decreased with the increase in O_(2)/Ar flow rate ratio from 0 to 0.25,proving that increasing the O_(2)/Ar flow rate ratio during film growth can reduce the concentration of oxygen vacancy defects in a-Ga_(2)O_(3) films.In this case,a-Ga_(2)O_(3) with optimal properties can be obtained.This work provides a research basis for high-performance flexible and rigid deep ultraviolet solar-blind detection devices based on a-Ga_(2)O_(3) films.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10979069)the "Hundred Talent Program" of Chinese Academy of Sciences
文摘As essential electrochromic（EC） materials are related to energy savings in fenestration technology,tungsten oxide（WO3） films have been intensively studied recently.In order to achieve better understanding of the mechanism of EC properties,and thus facilitate optimization of device performance,clarification of the correlation between cation storage and transfer properties and the coloration performance is needed.In this study,transparent polycrystalline and amorphous WO3 thin films were deposited on SnO2：F-coated glass substrates by the pulsed laser deposition technique.Investigation into optical transmittance in a wavelength range of 400-800 nm measured at a current density of 130 μA·cm-2 with the applied potential ranging from 3.2 to 2.2 V indicates that polycrystalline films have a larger optical modulation of ～ 30% at 600 nm and a larger coloration switch time of 95 s in the whole wavelength range compared with amorphous films（～ 24% and 50 s）.Meanwhile,under the same conditions,polycrystalline films show a larger lithium storage capacity corresponding to a Li/W ratio of 0.5,a smaller lithium diffusion coefficient（2×10-12cm2·s-1 for Li/W=0.24） compared with the amorphous ones,which have a Li/W ratio of 0.29 and a coefficient of ～2.5×10-11cm2·s-1 as Li/W=0.24.These results demonstrate that the large optical modulation relates to the large lithium storage capacity,and the fast coloration transition is associated with fast lithium diffusion.
基金Project(21471054)supported by the National Natural Science Foundation of China
文摘A novel WO3-x/TiO2 film as photoanode was synthesized for photoelectrocatalytic（PEC） reduction of CO2 into formic acid（HCOOH）. The films prepared by doctor blade method were characterized with X-ray diffractometer（XRD）, scanning electron microscope（SEM） and transmission electron microscope（TEM）. The existence of oxygen vacancies in the WO3-x was confirmed with an X-ray photoelectron spectroscopy（XPS）, and the accurate oxygen index was determined by a modified potentiometric titrimetry method. After 3h of photoelectrocatalytic reduction, the formic acid yield of the WO3-x/TiO2 film is 872 nmol/cm^2, which is 1.83 times that of the WO3/TiO2 film. The results of PEC performance demonstrate that the introduction of WO3-x nanoparticles can improve the charge transfer performance so as to enhance the performance of PEC reduction of CO2 into formic acid.
基金Project(50902062)supported by the National Natural Science Foundation of ChinaProject(KKZ1200927002)supported by Key Programme of Kunming University of Science and Technology,China
文摘La0.72Ca0.28MnO3 thin films were deposited on untilted and 15° tilted LaAlO_3 （100） single crystalline substrates by pulsed laser deposition. The polycrystalline targets used in the deposition process were synthesized by sol-gel and coprecipitation methods, respectively. The structure, electrical transport properties and surface morphology of the targets and films were studied. It is found that, compared with coprecipitation method, the sol-gel target has more homogeneous components and larger density and grain size, thus the higher insulator-metal transition temperature and larger temperature coefficient of resistivity. The thin film prepared by sol-gel target has a uniform grain size and higher quality. The metal-insulator transition temperature is higher and the laser induced voltage signal is larger. Preparing the target by sol-gel method can largely improve the properties of corresponding thin films in pulsed laser deposition process.
