The mechanism of CO 2 methanation over Ru/ZrO 2 catalyst has been studied by means of diffuse reflectance infrared Fourier-transform spectroscopy. The results indicate that the formation of carbon-containing species o...The mechanism of CO 2 methanation over Ru/ZrO 2 catalyst has been studied by means of diffuse reflectance infrared Fourier-transform spectroscopy. The results indicate that the formation of carbon-containing species on the surface of catalyst is involved in the catalytic process. The adsorbed carbonate, formate and carbon monoxide can be detected on the surface of Ru/ZrO 2 catalyst. The surface carbonate and formate are much more abundant than the surface carbon monoxide. The surface carbonate and formate are main intermediates for the catalytic methanation of CO 2 over Ru/ZrO 2 catalyst, which can be directly hydrogenated to methane in the presence of hydrogen.展开更多
A series of Ni/ZrO_2 catalysts were synthesized by urea combustion method for CO_2 methanation.The effects of zirconium precursors and urea dosage on the structure and catalytic performance of the catalysts were teste...A series of Ni/ZrO_2 catalysts were synthesized by urea combustion method for CO_2 methanation.The effects of zirconium precursors and urea dosage on the structure and catalytic performance of the catalysts were tested.Results showed that the Ni/ZrO_2–O catalyst derived from zirconium oxynitrate hydrate exhibited better catalytic activity than the Ni/ZrO_2 catalyst because of its higher Ni dispersion and smaller Ni particle size.In addition,the urea dosage significantly influenced the low-temperature activity of the catalysts by affecting the metal–support interaction,Ni dispersion,and Ni particle size.The Ni/ZrO_2–O-0.4 catalyst with a urea-to-nitrate molar ratio of 0.4 exhibited the best catalytic activity owing to its moderate metal–support interaction,highest Ni dispersion,and smallest Ni particle size,achieving 69.2% CO_2 conversion and 100% CH_4 selectivity at 300℃,0.1 MPa,and a weight hour space velocity(WHSV)of 50,000 mL/(g·h).Moreover,the urea combustion method can lead to the entire phase transformation from monoclinic ZrO_2 to tetragonal ZrO_2 accompanied by the incorporation of oxygen vacancies in the ZrO_2 lattice.This phenomenon can also be related to the high catalytic activity of the as-prepared catalysts.展开更多
Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics;nevertheless,its fast degradation rate at the initial stage after implantation remains as one of the main ...Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics;nevertheless,its fast degradation rate at the initial stage after implantation remains as one of the main challenges to be resolved.ZrO_(2)-based coatings to reduce the degradation rate of the Mg-implants are an attractive solution since they show high biocompatibility and stability.In this work,the degradation,cytotoxicity,and antibacterial performance of ZrO_(2)thin films deposited by magnetron sputtering on a Mg-Zn-Ca alloy was evaluated.Short-term degradation of ZrO_(2)-coated and uncoated samples was assessed considering electrochemical techniques and H_(2)evolution(gas chromatography).Additionally,long term degradation was assessed by mass-loss measurements.The results showed that a 380 nm ZrO_(2)coating reduces the degradation rate and H_(2)evolution of the alloy during the initial 3 days after immersion but allows the degradation of the bare alloy for the long-term.The ZrO_(2)coating does not compromise the biocompatibility of the alloy and permits better cell adhesion and proliferation of mesenchymal stem cells directly on its surface,in comparison to the bare alloy.Finally,the ZrO_(2)coating prevents the adhesion and biofilm formation of S.aureus.展开更多
Energy consumption is increasing yearly all over the world due to the increase in population and demand of energy. The world largely depends on a hydroelectric energy supply, thermal electric energy supply which is al...Energy consumption is increasing yearly all over the world due to the increase in population and demand of energy. The world largely depends on a hydroelectric energy supply, thermal electric energy supply which is all non-renewable energy resources. Nevertheless, non-renewable energy resources are rapidly decreasing per year due to increasing rate of energy consumption. The quest for the discovery of another abundant resource of energy has attracted many scientists into development of renewable energy technologies like photovoltaic energy which are the technology that convert solar radiation into electricity. For the past several years, different photovoltaic devices like inorganic, organic, and hybrid solar cells have been invented using different methods for different application purposes. Moreover, high conversion efficiency of silicon solar cells, the high cost of module and complicated production processes involved in the production restricted commercialization of photovoltaic solar cells as a means of electricity supply. Among all organic solar cells, Dye-Sensitized Solar Cells (DSSCs) are the most efficient, low cost and easily implemented technology. This review paper focuses on clarifying the technological meaning of the structure of DSSCs, Various types of DSSCs materials, working electrode and working mechanism of DSSC, transparent and conductive substrate, nanocrystalline semiconductor film electrode, photosensisitizer (dye), electrolyte, carbon layer electrode, zinc oxide (ZnO) layer, zirconium dioxide (ZrO2) layer, benefits of DSSCs and application, the efficiency and challenges for research and development of DSSCs to upgrade the current efficiency.展开更多
Zirconium metal-organic frameworks ZrOBDC(where BDC=C6H4(COOH)2,terephthalic acid)doped and co-doped with rare earth ions Ln(ZrOBDC:Ln^3+,where Ln^3+=Eu3+and Tb^3+as well as Er^3+and Yb^3+)were used as precursors for ...Zirconium metal-organic frameworks ZrOBDC(where BDC=C6H4(COOH)2,terephthalic acid)doped and co-doped with rare earth ions Ln(ZrOBDC:Ln^3+,where Ln^3+=Eu3+and Tb^3+as well as Er^3+and Yb^3+)were used as precursors for the design of tetragonal rare earth doped zirconia nanoparticles(t-ZrO2:Ln^3+NPs)through annealing process.Preparation,characterization and luminescence properties of ZrOBDC:Ln^3+and ZrO2:Ln^3+NPs were investigated.The as-obtained t-ZrO2:Ln^3+NPs have high purity with an average size of 20-30 nm.The luminescence spectra of ZrOBDC:Tb^3+and ZrOBDC:Eu3+display strong green and red emission at around 544 and 611 nm which correspond to 5D4→7F5 and 5D0→7F2 transitions of Tb^3+and Eu3+ions,respectively.The green and red up-conversion emissions of ZrO2:Er^3+,Yb^3+NPs due to 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of the Er^3+ions are observed under 976 nm laser excitation.展开更多
文摘The mechanism of CO 2 methanation over Ru/ZrO 2 catalyst has been studied by means of diffuse reflectance infrared Fourier-transform spectroscopy. The results indicate that the formation of carbon-containing species on the surface of catalyst is involved in the catalytic process. The adsorbed carbonate, formate and carbon monoxide can be detected on the surface of Ru/ZrO 2 catalyst. The surface carbonate and formate are much more abundant than the surface carbon monoxide. The surface carbonate and formate are main intermediates for the catalytic methanation of CO 2 over Ru/ZrO 2 catalyst, which can be directly hydrogenated to methane in the presence of hydrogen.
文摘A series of Ni/ZrO_2 catalysts were synthesized by urea combustion method for CO_2 methanation.The effects of zirconium precursors and urea dosage on the structure and catalytic performance of the catalysts were tested.Results showed that the Ni/ZrO_2–O catalyst derived from zirconium oxynitrate hydrate exhibited better catalytic activity than the Ni/ZrO_2 catalyst because of its higher Ni dispersion and smaller Ni particle size.In addition,the urea dosage significantly influenced the low-temperature activity of the catalysts by affecting the metal–support interaction,Ni dispersion,and Ni particle size.The Ni/ZrO_2–O-0.4 catalyst with a urea-to-nitrate molar ratio of 0.4 exhibited the best catalytic activity owing to its moderate metal–support interaction,highest Ni dispersion,and smallest Ni particle size,achieving 69.2% CO_2 conversion and 100% CH_4 selectivity at 300℃,0.1 MPa,and a weight hour space velocity(WHSV)of 50,000 mL/(g·h).Moreover,the urea combustion method can lead to the entire phase transformation from monoclinic ZrO_2 to tetragonal ZrO_2 accompanied by the incorporation of oxygen vacancies in the ZrO_2 lattice.This phenomenon can also be related to the high catalytic activity of the as-prepared catalysts.
基金supported by CONACYT-Frontera-1740,CONACy T-CB-288101,CONACy T-299703,and DGAPAPAPIIT-IN101419 projectssupport from the CONACYT Ph.D.-scholarship(CVU 606030)+2 种基金the program Doctorado en Ciencia e Ingeniería de Materials at the Universidad Nacional Autónoma de Méxicothe support from the program Maestría y Doctorado en Ciencias Médicas,Odontológicas y de la Salud at the Universidad Nacional Autónoma de México and the Ph.D.scholarship from CONACy T(CVU 856985)the support from the program Posgrado de Doctorado en Ciencias en Biomedicina y Biotecnología Molecular,Escuela Nacional de Ciencias Biológicas at the Instituto Politécnico Nacional and the Ph.D.scholarship from CONACy T(CVU 739515)
文摘Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics;nevertheless,its fast degradation rate at the initial stage after implantation remains as one of the main challenges to be resolved.ZrO_(2)-based coatings to reduce the degradation rate of the Mg-implants are an attractive solution since they show high biocompatibility and stability.In this work,the degradation,cytotoxicity,and antibacterial performance of ZrO_(2)thin films deposited by magnetron sputtering on a Mg-Zn-Ca alloy was evaluated.Short-term degradation of ZrO_(2)-coated and uncoated samples was assessed considering electrochemical techniques and H_(2)evolution(gas chromatography).Additionally,long term degradation was assessed by mass-loss measurements.The results showed that a 380 nm ZrO_(2)coating reduces the degradation rate and H_(2)evolution of the alloy during the initial 3 days after immersion but allows the degradation of the bare alloy for the long-term.The ZrO_(2)coating does not compromise the biocompatibility of the alloy and permits better cell adhesion and proliferation of mesenchymal stem cells directly on its surface,in comparison to the bare alloy.Finally,the ZrO_(2)coating prevents the adhesion and biofilm formation of S.aureus.
文摘Energy consumption is increasing yearly all over the world due to the increase in population and demand of energy. The world largely depends on a hydroelectric energy supply, thermal electric energy supply which is all non-renewable energy resources. Nevertheless, non-renewable energy resources are rapidly decreasing per year due to increasing rate of energy consumption. The quest for the discovery of another abundant resource of energy has attracted many scientists into development of renewable energy technologies like photovoltaic energy which are the technology that convert solar radiation into electricity. For the past several years, different photovoltaic devices like inorganic, organic, and hybrid solar cells have been invented using different methods for different application purposes. Moreover, high conversion efficiency of silicon solar cells, the high cost of module and complicated production processes involved in the production restricted commercialization of photovoltaic solar cells as a means of electricity supply. Among all organic solar cells, Dye-Sensitized Solar Cells (DSSCs) are the most efficient, low cost and easily implemented technology. This review paper focuses on clarifying the technological meaning of the structure of DSSCs, Various types of DSSCs materials, working electrode and working mechanism of DSSC, transparent and conductive substrate, nanocrystalline semiconductor film electrode, photosensisitizer (dye), electrolyte, carbon layer electrode, zinc oxide (ZnO) layer, zirconium dioxide (ZrO2) layer, benefits of DSSCs and application, the efficiency and challenges for research and development of DSSCs to upgrade the current efficiency.
基金Project supported by Vietnam National Foundation for Science and Technology Development(NAFOSTED,103.03-2016.60)the project collaborated between Polish Academy of Sciences and Vietnam Academy of Sciences and Technology(QTPL01.01/18-19)
文摘Zirconium metal-organic frameworks ZrOBDC(where BDC=C6H4(COOH)2,terephthalic acid)doped and co-doped with rare earth ions Ln(ZrOBDC:Ln^3+,where Ln^3+=Eu3+and Tb^3+as well as Er^3+and Yb^3+)were used as precursors for the design of tetragonal rare earth doped zirconia nanoparticles(t-ZrO2:Ln^3+NPs)through annealing process.Preparation,characterization and luminescence properties of ZrOBDC:Ln^3+and ZrO2:Ln^3+NPs were investigated.The as-obtained t-ZrO2:Ln^3+NPs have high purity with an average size of 20-30 nm.The luminescence spectra of ZrOBDC:Tb^3+and ZrOBDC:Eu3+display strong green and red emission at around 544 and 611 nm which correspond to 5D4→7F5 and 5D0→7F2 transitions of Tb^3+and Eu3+ions,respectively.The green and red up-conversion emissions of ZrO2:Er^3+,Yb^3+NPs due to 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of the Er^3+ions are observed under 976 nm laser excitation.
