The adsorption and reaction of O + CN → OCN on Cu(100) are studied by using density functional theory and cluster model. Cu14 cluster model is used to simulate the surface. The calculated results show that the OCN...The adsorption and reaction of O + CN → OCN on Cu(100) are studied by using density functional theory and cluster model. Cu14 cluster model is used to simulate the surface. The calculated results show that the OCN species with the molecule perpendicular to the surface via N atom (N-down) is more favorable than other adsorption models, and the N-down at the bridge site is the most favorable. For N-down, calculated OCN symmetric and asymmetric stretching frequencies are all blue-shifted compared with the calculated values of free and in good agreement with the experiments. The charge transfer from the surface to the OCN species leads to that the bonding of OCN to the metal surface is largely ionic. The present studies also show that CN with the molecule perpendicular to the surface via C atom (NC-down) at the top site is the most stable. Except NC-down at the top site, the calculated CN stretching frequencies are all red-shifted. With O coadsorbed at the hollow site, the adsorption of NC-down at the next nearest bridge or top site is energetically more favorable than that at the adjacent hollow site. The reaction of O + CN → OCN on Cu(100) has no energy barrier via both Eley-Rideal and Langmuir-Hinshelwood processes.展开更多
The equations of the second and third order derivative curves of time with respect to potential for a reversible process in adsorption chronopotentiometry are derived and experimentally verified.
The nanowires-reticulated calcium silicate with a specific surface area more than 100 m^2/g was prepared by a hydrothermalprocess using hydrated lime(Ca(OH)_2,HL)and silica containing soluble fluoride,which was a ...The nanowires-reticulated calcium silicate with a specific surface area more than 100 m^2/g was prepared by a hydrothermalprocess using hydrated lime(Ca(OH)_2,HL)and silica containing soluble fluoride,which was a by-product of fluorine industry,and the soluble fluoride in raw silica was fixed as CaSiF_6 at the same time.The kinetic characteristics and mechanism of adsorbing phosphate by fluorine-containing calcium silicate were investigated in the experiments of phosphorus(P)removalfrom aqueous solution.The results show that the prepared fluorine-containing calcium silicate has excellent performance for adsorbing phosphate,the adsorption process appears to follow pseudo-second-order reaction kinetics and the process is mainly controlled by chemisorption.The product resulted from P adsorption is mainly composed of hydroxyapatite(HAP)and fluorapatite(FAP),which are further used as adsorbents of heavy metalion Cd^(2+) in aqueous solution and display excellent performance.展开更多
CdS quantum dots(QDs) sensitized TiO2 nanotube arrays photoelectrodes were investigated for their photovoltaic performance of quantum dots-sensitized solar cells. The highly ordered TiO2 nanotube arrays(TNAs) were...CdS quantum dots(QDs) sensitized TiO2 nanotube arrays photoelectrodes were investigated for their photovoltaic performance of quantum dots-sensitized solar cells. The highly ordered TiO2 nanotube arrays(TNAs) were synthesized on Ti foils by anodic oxidation method. Then CdS quantum dots were deposited onto the TiO2 nanotube arrays by successive ionic layer absorption and reaction(SILAR) method to serve as the sensitizers. Cd(NO3)2 and Na2S were used as the precursor materials of Cd+ and S2- ions, respectively. It is found that the CdS QDs sensitizer may significantly increase the light response of TiO2 nanotube arrays. With increasing CdS QDs deposition cycles, the visible light response increases. Maximum photocurrent was obtained for the QDs that have an absorption peak at about 500 nm. Under AM 1.5 G illuminations(100 mW cm^-2), a 4.85 mA/cm^2 short circuit current density was achieved, and the maximium energy conversion efficiency of the asprepared CdS QDs-sensitized TNAs solar cells was obtained as high as 0.81% at five SILAR cycles.展开更多
The geopolymer synthesized by alkali-activated fly ash was firstly used as a novel photocatalyst for degradation of methylene blue (MB) dye from wastewater. The geopolymer is composed of nanoparticulates with an ave...The geopolymer synthesized by alkali-activated fly ash was firstly used as a novel photocatalyst for degradation of methylene blue (MB) dye from wastewater. The geopolymer is composed of nanoparticulates with an average particle size of about 50 nm, More than 90% of pore volume in the fly ash-based geopolymet predominately centralized on the pore size in the range of 17-700 nm. The degradation efficiency of MB dye by fly ash-based geopolymer catalyst was up to 92.79% under UV irradiation due to the synergistic effect of adsorption and semiconductor photocatalysis. The pseudo-first-order and pseudo-second-order rate equations as well as intra-particle diffusion rate equation were employed to correlate analysis for the adsorption kinetics of MB dye, The experimental data agreed well with pseudo-second-order rate equation in both cases of with UV and without UV irradiations. The intra-particle diffusion process is not the rate determining step. The photocatalytic degradation of MB dye in solution obeys third-order reaction kinetics.展开更多
基金This research was supported by the National Natural Science Foundation of China (20273013, 20303002), the Educational Foundation of Fujian Province (2002F010), and the Foundation of State Key Laboratory of Structural Chemistry (020051) and Fuzhou University (2004XY04)
文摘The adsorption and reaction of O + CN → OCN on Cu(100) are studied by using density functional theory and cluster model. Cu14 cluster model is used to simulate the surface. The calculated results show that the OCN species with the molecule perpendicular to the surface via N atom (N-down) is more favorable than other adsorption models, and the N-down at the bridge site is the most favorable. For N-down, calculated OCN symmetric and asymmetric stretching frequencies are all blue-shifted compared with the calculated values of free and in good agreement with the experiments. The charge transfer from the surface to the OCN species leads to that the bonding of OCN to the metal surface is largely ionic. The present studies also show that CN with the molecule perpendicular to the surface via C atom (NC-down) at the top site is the most stable. Except NC-down at the top site, the calculated CN stretching frequencies are all red-shifted. With O coadsorbed at the hollow site, the adsorption of NC-down at the next nearest bridge or top site is energetically more favorable than that at the adjacent hollow site. The reaction of O + CN → OCN on Cu(100) has no energy barrier via both Eley-Rideal and Langmuir-Hinshelwood processes.
文摘The equations of the second and third order derivative curves of time with respect to potential for a reversible process in adsorption chronopotentiometry are derived and experimentally verified.
基金Funded by the Science and Technology-oriented Mid and Small-scale Enterprises Innovational Foundation of Ministry of Science and Technology of China(11C26216406395)
文摘The nanowires-reticulated calcium silicate with a specific surface area more than 100 m^2/g was prepared by a hydrothermalprocess using hydrated lime(Ca(OH)_2,HL)and silica containing soluble fluoride,which was a by-product of fluorine industry,and the soluble fluoride in raw silica was fixed as CaSiF_6 at the same time.The kinetic characteristics and mechanism of adsorbing phosphate by fluorine-containing calcium silicate were investigated in the experiments of phosphorus(P)removalfrom aqueous solution.The results show that the prepared fluorine-containing calcium silicate has excellent performance for adsorbing phosphate,the adsorption process appears to follow pseudo-second-order reaction kinetics and the process is mainly controlled by chemisorption.The product resulted from P adsorption is mainly composed of hydroxyapatite(HAP)and fluorapatite(FAP),which are further used as adsorbents of heavy metalion Cd^(2+) in aqueous solution and display excellent performance.
基金Funded by Major State Basic Research Development Program of China (973 Program) (No.2009CB939704)Key Project of Chinese Ministry of Education (No.309021)
文摘CdS quantum dots(QDs) sensitized TiO2 nanotube arrays photoelectrodes were investigated for their photovoltaic performance of quantum dots-sensitized solar cells. The highly ordered TiO2 nanotube arrays(TNAs) were synthesized on Ti foils by anodic oxidation method. Then CdS quantum dots were deposited onto the TiO2 nanotube arrays by successive ionic layer absorption and reaction(SILAR) method to serve as the sensitizers. Cd(NO3)2 and Na2S were used as the precursor materials of Cd+ and S2- ions, respectively. It is found that the CdS QDs sensitizer may significantly increase the light response of TiO2 nanotube arrays. With increasing CdS QDs deposition cycles, the visible light response increases. Maximum photocurrent was obtained for the QDs that have an absorption peak at about 500 nm. Under AM 1.5 G illuminations(100 mW cm^-2), a 4.85 mA/cm^2 short circuit current density was achieved, and the maximium energy conversion efficiency of the asprepared CdS QDs-sensitized TNAs solar cells was obtained as high as 0.81% at five SILAR cycles.
基金financially supported by Industrial Key Project of Shaanxi Province(No.2010K01-080)Open Fund of State Key Laboratory of Architecture Science and Technology in West China(XAUAT)+1 种基金Xi'an University of Architecture and Technology(No.10KF05)Scientific Research Program Funded by Shaanxi Provincial Education Department(No.12JK0579)
文摘The geopolymer synthesized by alkali-activated fly ash was firstly used as a novel photocatalyst for degradation of methylene blue (MB) dye from wastewater. The geopolymer is composed of nanoparticulates with an average particle size of about 50 nm, More than 90% of pore volume in the fly ash-based geopolymet predominately centralized on the pore size in the range of 17-700 nm. The degradation efficiency of MB dye by fly ash-based geopolymer catalyst was up to 92.79% under UV irradiation due to the synergistic effect of adsorption and semiconductor photocatalysis. The pseudo-first-order and pseudo-second-order rate equations as well as intra-particle diffusion rate equation were employed to correlate analysis for the adsorption kinetics of MB dye, The experimental data agreed well with pseudo-second-order rate equation in both cases of with UV and without UV irradiations. The intra-particle diffusion process is not the rate determining step. The photocatalytic degradation of MB dye in solution obeys third-order reaction kinetics.