Nitrogen-doped TiO2 nanotubes array were synthesized to improve the photocatalytic efficiency by annealing the anodized titania nanotubes with ammonia at 500℃.Detailed structural analysis revealed that the nitrogen-d...Nitrogen-doped TiO2 nanotubes array were synthesized to improve the photocatalytic efficiency by annealing the anodized titania nanotubes with ammonia at 500℃.Detailed structural analysis revealed that the nitrogen-doped titania nanotubes are of highly ordered structure,and exhibit a decreased phase transformation temperature compared with those that are not doped,as evidenced by the decrease in full width at half maximum(FWHM)of the(110)peak of rutile phase and the occurrence of the typical Raman peaks of rutile phase at 196,235,442,610 cm -1 .According to the photocatalytic degradation of methyl orange under visible light irradiation,the nitrogen-doped TiO2 nanotubes exhibit enhanced photocatalytic efficiency compared with their non-doped nanotubes,which might be a result of either the nitrogen doping induced band gap narrowing or the synergistic effect produced by both nitrogen and fluorine dopants.展开更多
The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current ...The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current perovskite solar cells suffer from some obstacles such as non-radiative charge recombination, mismatched absorption, light induced degradation for the further improvement of the power conversion efficiency and operational stability towards practical application. The rare-earth elements have been recently employed to effectively overcome these drawbacks according to their unique photophysical properties. Herein, the recent progress of the application of rare-earth ions and their functions in perovskite solar cells were systematically reviewed. As it was revealed that the rare-earth ions can be coupled with both charge transport metal oxides and photosensitive perovskites to regulate the thin film formation, and the rare-earth ions are embedded either substitutionally into the crystal lattices to adjust the optoelectronic properties and phase structure, or interstitially at grain boundaries and surface for effective defect passivation. In addition, the reversible oxidation and reduction potential of rare-earth ions can prevent the reduction and oxidation of the targeted materials. Moreover, owing to the presence of numerous energetic transition orbits, the rare-earth elements can convert low-energy infrared photons or high-energy ultraviolet photons into perovskite responsive visible light, to extend spectral response range and avoid high-energy light damage. Therefore, the incorporation of rare-earth elements into the perovskite solar cells have demonstrated promising potentials to simultaneously boost the device efficiency and stability.展开更多
Chopped and spread maize stalks improve soil structure and fertility. However, because of the absence of research on airflow distribution in the chopping chamber, improvement of the spreading uniformity of chopped sta...Chopped and spread maize stalks improve soil structure and fertility. However, because of the absence of research on airflow distribution in the chopping chamber, improvement of the spreading uniformity of chopped stalks has been limited. Therefore, in this study, computational fluid dynamics (CFD) technology was applied to analyze the influence of structural and operational parameters of the chopping and spreading machine on the velocity, pressure, and turbulent kinetic energy distribution of airflow in the chopping chamber. The experimental factors considered were the relative position angle (RPA) between the collecting-chopping shaft and the sliding-supporting shaft, working velocity (WV) of the chopping chamber, and rotational velocity of the collecting-chopping blade (RVCCB). The results revealed that RPA and RVCCB had a significant influence on the maximum negative pressure in the inlet (MNPI), the proportion of negative pressure area at inlet (PNPAI), and the maximum pressure drop at inlet and outlet (MPDIO). Additionally, RVCCB had a strong influence on the maximum velocity, average velocity, and velocity variation coefficient of airflow at the outlet. Moreover, maximum turbulence (MT) and maximum turbulent kinetic energy dissipation rate (MTKEDR) showed a positive relationship with RVCCB. To determine the values of RPA, RVCCB, and WV, a multivariate parameters optimization regression model was constructed, which yielded the optimal values of 15°, 1800 r/min, and 0.50 m/s, respectively. Subsequently, a hyperbolic spiral-type guiding shell with an arc length of 90° was designed to enhance the uniform distribution of airflow in the chopping chamber. Finally, a validation experiment of airflow distribution was conducted. The results showed that the velocity difference between the simulation and the validation experiment was less than 15%, indicating the accuracy of CFD simulation, and the spreading uniformities of the chopped stalks were better than national standards. These findings can serve as technical and theoretical support for the design and optimization of chopping and spreading machines.展开更多
基金Project(2008A430016)supported by the Foundation of Henan Education Department,Chinaprojects(50902125+1 种基金50872125)supported by the National Natural Science Foundation of Chinaproject supported by the China Postdoctoral Science Foundation
文摘Nitrogen-doped TiO2 nanotubes array were synthesized to improve the photocatalytic efficiency by annealing the anodized titania nanotubes with ammonia at 500℃.Detailed structural analysis revealed that the nitrogen-doped titania nanotubes are of highly ordered structure,and exhibit a decreased phase transformation temperature compared with those that are not doped,as evidenced by the decrease in full width at half maximum(FWHM)of the(110)peak of rutile phase and the occurrence of the typical Raman peaks of rutile phase at 196,235,442,610 cm -1 .According to the photocatalytic degradation of methyl orange under visible light irradiation,the nitrogen-doped TiO2 nanotubes exhibit enhanced photocatalytic efficiency compared with their non-doped nanotubes,which might be a result of either the nitrogen doping induced band gap narrowing or the synergistic effect produced by both nitrogen and fluorine dopants.
基金Project supported by the National Key R&D Program of China (Grant No. 2020YFA07099003)Six Talent Peaks Project of Jiangsu Province, China (Grant No. 2019-XNY-013)a fellowship from the China Postdoctoral Science Foundation (Grant No. 2020M672181)。
文摘The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current perovskite solar cells suffer from some obstacles such as non-radiative charge recombination, mismatched absorption, light induced degradation for the further improvement of the power conversion efficiency and operational stability towards practical application. The rare-earth elements have been recently employed to effectively overcome these drawbacks according to their unique photophysical properties. Herein, the recent progress of the application of rare-earth ions and their functions in perovskite solar cells were systematically reviewed. As it was revealed that the rare-earth ions can be coupled with both charge transport metal oxides and photosensitive perovskites to regulate the thin film formation, and the rare-earth ions are embedded either substitutionally into the crystal lattices to adjust the optoelectronic properties and phase structure, or interstitially at grain boundaries and surface for effective defect passivation. In addition, the reversible oxidation and reduction potential of rare-earth ions can prevent the reduction and oxidation of the targeted materials. Moreover, owing to the presence of numerous energetic transition orbits, the rare-earth elements can convert low-energy infrared photons or high-energy ultraviolet photons into perovskite responsive visible light, to extend spectral response range and avoid high-energy light damage. Therefore, the incorporation of rare-earth elements into the perovskite solar cells have demonstrated promising potentials to simultaneously boost the device efficiency and stability.
基金supported by Natural Science Foundation of Henan Province(Grant No.242300421560)Science and Technology Research Project of Henan(Grant No.232102110273)+2 种基金the Scientific Research Foundation for Advanced Talents of Henan University of Technology(Grant No.2022BS077)Training Plan of Young Backbone Teachers in Colleges and Universities in Henan Province(Grant No.2020GGJS088)the Cultivation Programme for Young Backbone Teachers in Henan University of Technology(Grant No.0503/21420191).
文摘Chopped and spread maize stalks improve soil structure and fertility. However, because of the absence of research on airflow distribution in the chopping chamber, improvement of the spreading uniformity of chopped stalks has been limited. Therefore, in this study, computational fluid dynamics (CFD) technology was applied to analyze the influence of structural and operational parameters of the chopping and spreading machine on the velocity, pressure, and turbulent kinetic energy distribution of airflow in the chopping chamber. The experimental factors considered were the relative position angle (RPA) between the collecting-chopping shaft and the sliding-supporting shaft, working velocity (WV) of the chopping chamber, and rotational velocity of the collecting-chopping blade (RVCCB). The results revealed that RPA and RVCCB had a significant influence on the maximum negative pressure in the inlet (MNPI), the proportion of negative pressure area at inlet (PNPAI), and the maximum pressure drop at inlet and outlet (MPDIO). Additionally, RVCCB had a strong influence on the maximum velocity, average velocity, and velocity variation coefficient of airflow at the outlet. Moreover, maximum turbulence (MT) and maximum turbulent kinetic energy dissipation rate (MTKEDR) showed a positive relationship with RVCCB. To determine the values of RPA, RVCCB, and WV, a multivariate parameters optimization regression model was constructed, which yielded the optimal values of 15°, 1800 r/min, and 0.50 m/s, respectively. Subsequently, a hyperbolic spiral-type guiding shell with an arc length of 90° was designed to enhance the uniform distribution of airflow in the chopping chamber. Finally, a validation experiment of airflow distribution was conducted. The results showed that the velocity difference between the simulation and the validation experiment was less than 15%, indicating the accuracy of CFD simulation, and the spreading uniformities of the chopped stalks were better than national standards. These findings can serve as technical and theoretical support for the design and optimization of chopping and spreading machines.
