H2 generation from a thermochemical water-splitting reaction was performed using a sol-gel derived Ni-ferrite. The sol-gel synthesis involved addition of nickel chloride hexahydrate （NiCl2@6H2O） and ferrous chloride...H2 generation from a thermochemical water-splitting reaction was performed using a sol-gel derived Ni-ferrite. The sol-gel synthesis involved addition of nickel chloride hexahydrate （NiCl2@6H2O） and ferrous chloride tetrahydrate （FeCl2·4H2O） in ethanol followed by gelation using propylene oxide. The gels were aged, dried and calcined at 900 ℃in air or N2 environment. The powders thus obtained were characterized using X-ray diffraction （XRD）. This analysis revealed a nominally phase pure Ni-ferrite （NiFe204） composition for the gels calcined in air, whereas those calcined in N2 environment exhibited primarily Ni04Fe2.604 composition mixed with metallic Ni. Particle size and specific surface area （SSA） of the ferrite powders were analyzed using scanning electron microscopy （SEM） and Brauner-Emmett-Teller （BET） surface area analyzer, respectively. The ferrites were placed in a packed bed reactor and water-splitting reaction was carried out at 700 ℃, 800 ℃, and 900 ℃. After water-splitting reaction, oxidized ferrites were regenerated at 900 ℃ for 2 h in N2 environment. Together water-splitting and regeneration steps designated as one thermochemical cycle. In four consecutive thermochemical cycles performed using NiFe204, an average of 40 mL of H2/g per cycle was generated at water-splitting temperature of 900 ℃, which was about five times higher than the average H2 produced at 700 ℃.展开更多
Global climate models have indicated high probability of drought occurrences in the coming future decades due to the impacts of climate change caused by a mass release of CO2. Thus, climate change regarding elevated a...Global climate models have indicated high probability of drought occurrences in the coming future decades due to the impacts of climate change caused by a mass release of CO2. Thus, climate change regarding elevated ambient CO2 and drought may consequently affect the growth of crops. In this study, plant physiology, soil carbon, and soil enzyme activities were measured to investigate the impacts of elevated C02 and drought stress on a Stagn[c Anthrosol planted with soybean （Glycine ma,z）. Treatments of two CO2 levels, three soil moisture levels, and two soil cover types were established. The results indicated that elevated CO2 and drought stress significantly affected plant physiology. The inhibition of plant physiology by drought stress was mediated via prompted photosynthesis and water use efficiency under elevated CO2 conditions. Elevated CO2 resulted in a longer retention time of dissolved organic carbon （DOC） in soil, probably by improving the soil water effectiveness for organic decomposition and mineralization. Drought stress significantly decreased C：N ratio and microbial biomass carbon （MBC）, but the interactive effects of drought stress and CO2 on them were not significant. Elevated CO2 induced an increase in invertase and catalase activities through stimulated plant root exudation. These results suggested that drought stress had significant negative impacts on plant physiology, soil carbon, and soil enzyme activities, whereas elevated CO2 and plant physiological feedbacks indirectly ameliorated these impacts.展开更多
文摘H2 generation from a thermochemical water-splitting reaction was performed using a sol-gel derived Ni-ferrite. The sol-gel synthesis involved addition of nickel chloride hexahydrate （NiCl2@6H2O） and ferrous chloride tetrahydrate （FeCl2·4H2O） in ethanol followed by gelation using propylene oxide. The gels were aged, dried and calcined at 900 ℃in air or N2 environment. The powders thus obtained were characterized using X-ray diffraction （XRD）. This analysis revealed a nominally phase pure Ni-ferrite （NiFe204） composition for the gels calcined in air, whereas those calcined in N2 environment exhibited primarily Ni04Fe2.604 composition mixed with metallic Ni. Particle size and specific surface area （SSA） of the ferrite powders were analyzed using scanning electron microscopy （SEM） and Brauner-Emmett-Teller （BET） surface area analyzer, respectively. The ferrites were placed in a packed bed reactor and water-splitting reaction was carried out at 700 ℃, 800 ℃, and 900 ℃. After water-splitting reaction, oxidized ferrites were regenerated at 900 ℃ for 2 h in N2 environment. Together water-splitting and regeneration steps designated as one thermochemical cycle. In four consecutive thermochemical cycles performed using NiFe204, an average of 40 mL of H2/g per cycle was generated at water-splitting temperature of 900 ℃, which was about five times higher than the average H2 produced at 700 ℃.
基金supported by the National Natural Science Foundation of China (No.51309053)the Fundamental Research Funds for the Central Universities-Donghua University (DHU) Distinguished Young Professor Program, China (No.B201310)
文摘Global climate models have indicated high probability of drought occurrences in the coming future decades due to the impacts of climate change caused by a mass release of CO2. Thus, climate change regarding elevated ambient CO2 and drought may consequently affect the growth of crops. In this study, plant physiology, soil carbon, and soil enzyme activities were measured to investigate the impacts of elevated C02 and drought stress on a Stagn[c Anthrosol planted with soybean （Glycine ma,z）. Treatments of two CO2 levels, three soil moisture levels, and two soil cover types were established. The results indicated that elevated CO2 and drought stress significantly affected plant physiology. The inhibition of plant physiology by drought stress was mediated via prompted photosynthesis and water use efficiency under elevated CO2 conditions. Elevated CO2 resulted in a longer retention time of dissolved organic carbon （DOC） in soil, probably by improving the soil water effectiveness for organic decomposition and mineralization. Drought stress significantly decreased C：N ratio and microbial biomass carbon （MBC）, but the interactive effects of drought stress and CO2 on them were not significant. Elevated CO2 induced an increase in invertase and catalase activities through stimulated plant root exudation. These results suggested that drought stress had significant negative impacts on plant physiology, soil carbon, and soil enzyme activities, whereas elevated CO2 and plant physiological feedbacks indirectly ameliorated these impacts.
