Annealing temperature dependent on morphology and electrochemical properties of ZnFe2O4 nanoparticles synthesized by sol-gel method

A series of ZnFe2O4 nanocrystals were synthesized by sol-gel method. The surface morphology, structure and the electrochemical performace of the materials annealed in the temperature range of 500-800°C were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), Multipoint N2 adsorption-desorption experiment, constant current charging-discharging test, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) techniques. Consequently, the morphology and electrochemical performance of these materials are very sensitive to the sintering temperature. ZnFe2O4 material treated at 600°C exhibits the initial reversible capacity of 1384.4 mAh g-1 and retains the highest capacity of 622 mAh g-1 after 50 cycles. The superior electrochemical performance is attributed to its smaller charge transfer resistance of 43.9 ω and higher lithium ion diffusion coefficient of 2.01×10-15 cm2 s-1, which due to the morphology with the smaller particle size and higher dispersibility

A review of magnesium aluminum chloride complex electrolytes for Mg batteries

Developing suitable electrolytes with high oxidation decomposition potential, low cost, and good compatibility with electrode materials has been a critical challenge in realizing practical magnesium batteries. The emerging magnesium aluminum chloride complex (MACC) electrolytes based on inorganic chloride salts exhibit high Coulombic efficiencies for magnesium batteries. This review summarizes recent studies of MACC electrolytes, focusing on the synthesis, characterization, and chemical environment of Mg species, electrolytic conditioning of electrolytes, and their application in typical magnesium batteries. The electrolyte evolution and influencing factor of electrolytic conditioning are discussed, and several kinds of conditioning-free MACC electrolytes are further introduced. Finally, future trends and perspectives in this field are discussed

Combining system dynamic model and CLUE-S model to improve land use scenario analyses at regional scale: A case study of Sangong watershed in Xinjiang, China

Uses of models of land use change are primary tools for analyzing the causes and consequences of land use changes, assessing the impacts of land use change on ecosystems and supporting land use planning and policy. However, no single model is able to capture all of key processes essential to explore land use change at different scales and make a full assessment of driving factors and impacts. Based on the multi-scale characteristics of land use change, combination and integration of currently existed models of land use change could be a feasible solution. Taken Sangong watershed as a case study, this paper describes an integrated methodology in which the conversion of land use and its effect model (CLUE), a spatially explicit land use change model, has been combined with a system dynamic model (SD) to analyze land use dynamics at different scales. A SD model is used to calculate area changes in demand for land types as a whole while a CLUE model is used to transfer these demands to land use patterns. Without the spatial consideration, the SD model ensures an appropriate treatment of macro-economic, demographic and technology developments, and changes in economic policies influencing the demand and supply for land use in a specific region. With CLUE model the land use change has been simulated at a high spatial resolution with the spatial consideration of land use suitability, spatial policies and restrictions to satisfy the balance between land use demand and supply. The application of the combination of SD and CLUE model in Sangong watershed suggests that this methodology have the ability to reflect the complex behaviors of land use system at different scales to some extent and be a useful tool for analysis of complex land use driving factors such as land use policies and assessment of its impacts on land use change. The established SD model was fitted or calibrated with the 1987-1998 data and validated with the 1998-2004 data; combining SD model with CLUE-S model, future land use scenarios were analyzed during 2004-2030. This work could be used for better understanding of the possible impacts of land use change on terrestrial ecosystem and provide scientific support for land use planning and managements of the watershed. (C) 2010 Elsevier B.V. All rights reserved

Rotating electrode methods and oxygen reduction electrocatalysts

Rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) techniques are one kind of the important and commonly used methods in electrochemical science and technology, particularly, in the fundamental understanding of electrochemical catalytic reaction mechanisms such as electrocatalytic oxygen reduction reaction (ORR). The kinetics and mechanisms of ORR catalyzed by both noble metal- and nonnoble metal-based electrocatalysts are the most important aspects in fuel cell and other ORR-related electrochemical technologies. Using RDE and RRDE to evaluate the activities of catalysts and their catalyzed ORR mechanisms is necessary and also one of the most feasible approaches in the development of ORR electrocatalysts.Peer reviewed: YesNRC publication: Ye

Validation of a Process-Based Agro-Ecosystem Model (Agro-IBIS) for Maize in Xinjiang, Northwest China

Agricultural oasis expansion and intensive management practices have occurred in arid and semiarid regions of China during the last few decades. Accordingly, regional carbon and water budgets have been profoundly impacted by agroecosystems in these regions. Therefore, study on the methods used to accurately estimate energy, water, and carbon exchanges is becoming increasingly important. Process-based models can represent the complex processes between land and atmosphere among agricultural ecosystems. However, before the models can be applied they must be validated under different environmental and climatic conditions. In this study, a process-based agricultural ecosystem model (Agro-IBIS) was validated for maize crops using 3 years of soil and biometric measurements at Wulanwusu agrometeorological site (WAS) located in the Shihezi oasis in Xinjiang, northwest China. The model satisfactorily represented leaf area index (LAI) during the growing season, simulating its peak values within the magnitude of 0–10%. The total biomass carbon was overestimated by 15%, 8%, and 16% in 2004, 2005, and 2006, respectively. The model satisfactorily simulated the soil temperature (0–10 cm) and volumetric water content (VWC) (0–25 cm) of farmland during the growing season. However, it overestimated soil temperature approximately by 4 ◦C and VWC by 15–30% during the winter, coinciding with the period of no vegetation cover in Xinjiang. Overall, the results indicate that the model could represent crop growth, and seems to be applicable in multiple sites in arid oases agroecosystems of Xinjiang. Future application of the model will impose more comprehensive validation using eddy covariance flux data, and consider including dynamics of crop residue and improving characterization of the final stage of leaf development

Applications of RDE and RRDE methods in oxygen reduction reaction

This chapter reviews the applications of rotating disk electrode (RDE) and Rotating ring-disk electrode (RRDE) techniques in Oxygen reduction reaction (ORR) research and its associated catalyst evaluation. Some typical examples for RDE and RRDE analysis in obtaining the ORR kinetic information such as the overall electron-transfer number, electron-transfer coefficiency, and exchange current density are also given in this chapter. It demonstrates that both RDE and RRDE methods are the powerful tools in an ORR study, and using RDE and RRDE methods, ORR has been successfully studied on Pt electrode, carbon electrode, monolayer metal catalyst, Pt-based catalyst, and non-noble metal-based catalysts, respectively.Peer reviewed: YesNRC publication: Ye