Ni–MgO nano‐composites were prepared on carbon anodes by electrodeposition from a nickel Watts bath in the presence of fine MgO reinforcement particles. Their performance as electrocata‐lysts for the oxidation of m...Ni–MgO nano‐composites were prepared on carbon anodes by electrodeposition from a nickel Watts bath in the presence of fine MgO reinforcement particles. Their performance as electrocata‐lysts for the oxidation of methanol and ethanol in alkaline medium was investigated and compared with that of carbon coated pure Ni （Ni/C）. The chemical composition, phase structure, and surface morphology of the deposited nano‐composites were studied by energy dispersive X‐ray spectros‐copy, X‐ray diffractometry, and scanning electron microscopy, respectively. Different electrochemi‐cal techniques were used to estimate the catalytic activity of the prepared electrocatalyst anodes, including cyclic voltammetry （CV）, chronoamperometry, and electrochemical impedance spectros‐copy （EIS）. The Ni/C electrocatalyst alone exhibited remarkably low catalytic activity and poor stability toward the electrooxidation process. The inclusion of MgO significantly promoted the cata‐lytic activity of the Ni catalyst for the alcohol electrooxidation and enhanced its poisoning re‐sistance. The EIS results confirmed those of CV and revealed a lower charge transfer resistance and enhanced roughness for the Ni–MgO/C nano‐composite electrodes compared with those of Ni/C.展开更多
Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3.5% sodium ch...Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3.5% sodium chloride （NaCl） solutions by cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS）, rotating disk electrode （RDE） and rotating ring-disk electrode （RRDE）. The cyclic voltammetric results demonstrated the cathodic process on Q235 carbon steel in O2-saturated 3.5% NaCl solution contains three reactions： dissolved oxygen reduction, iron oxides reduction and hydrogen evolution. The peak potential of oxygen reduction reaction （ORR） is - 0.85 V vs Ag/AgCl, 3 molL^-1 KCI. The EIS results indicated that the ORR occurring on Q235 carbon steel is a 4-electron process and that no finite diffusion is caused by the intermediate of H2O2 produced by ORR. The RDE and RRDE voltammograms confirmed the EIS results and it was found that the number of transferred electrons for ORR was nearly 4, i.e., dissolved oxygen reduced to water.展开更多
The paper summarizes the research progresses of electrical capacitance and electrical resistance assessing tree vigor and points out the development direction of the study. Researches show that electrical capacitance ...The paper summarizes the research progresses of electrical capacitance and electrical resistance assessing tree vigor and points out the development direction of the study. Researches show that electrical capacitance is related to the indexes of periodic growth rate of trees, foliar biomass and diameter of breast height, while electrical resistance has inverse relationships with the above indexes. Eiectrical capacitance and electrical resistance change when trees suffer environmental stress, insect pests or diseases. Especially, changes of electrical resistance are observed before symptom expression of some tree diseases, which can help to establish a certain disease potential hazard rating system. Mechanisms of electrical capacitance and resistance assessing tree vigor, especially in molecule level, still need to be studied and the application criteria of electrical resistance and capacitance need to be established.展开更多
文摘Ni–MgO nano‐composites were prepared on carbon anodes by electrodeposition from a nickel Watts bath in the presence of fine MgO reinforcement particles. Their performance as electrocata‐lysts for the oxidation of methanol and ethanol in alkaline medium was investigated and compared with that of carbon coated pure Ni （Ni/C）. The chemical composition, phase structure, and surface morphology of the deposited nano‐composites were studied by energy dispersive X‐ray spectros‐copy, X‐ray diffractometry, and scanning electron microscopy, respectively. Different electrochemi‐cal techniques were used to estimate the catalytic activity of the prepared electrocatalyst anodes, including cyclic voltammetry （CV）, chronoamperometry, and electrochemical impedance spectros‐copy （EIS）. The Ni/C electrocatalyst alone exhibited remarkably low catalytic activity and poor stability toward the electrooxidation process. The inclusion of MgO significantly promoted the cata‐lytic activity of the Ni catalyst for the alcohol electrooxidation and enhanced its poisoning re‐sistance. The EIS results confirmed those of CV and revealed a lower charge transfer resistance and enhanced roughness for the Ni–MgO/C nano‐composite electrodes compared with those of Ni/C.
基金supported by the National Natural Science Foundation of China ( Grant No 40876041)Science and Technology Basic Research Program of Qingdao (Grant No 09-1-3-16-jch)the National Key Technology Research and Development Program of China (Grant No 2007 BAB27B01)
文摘Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3.5% sodium chloride （NaCl） solutions by cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS）, rotating disk electrode （RDE） and rotating ring-disk electrode （RRDE）. The cyclic voltammetric results demonstrated the cathodic process on Q235 carbon steel in O2-saturated 3.5% NaCl solution contains three reactions： dissolved oxygen reduction, iron oxides reduction and hydrogen evolution. The peak potential of oxygen reduction reaction （ORR） is - 0.85 V vs Ag/AgCl, 3 molL^-1 KCI. The EIS results indicated that the ORR occurring on Q235 carbon steel is a 4-electron process and that no finite diffusion is caused by the intermediate of H2O2 produced by ORR. The RDE and RRDE voltammograms confirmed the EIS results and it was found that the number of transferred electrons for ORR was nearly 4, i.e., dissolved oxygen reduced to water.
基金Supported by the National Nature Science Foundation of China (grant No. 30471384 )
文摘The paper summarizes the research progresses of electrical capacitance and electrical resistance assessing tree vigor and points out the development direction of the study. Researches show that electrical capacitance is related to the indexes of periodic growth rate of trees, foliar biomass and diameter of breast height, while electrical resistance has inverse relationships with the above indexes. Eiectrical capacitance and electrical resistance change when trees suffer environmental stress, insect pests or diseases. Especially, changes of electrical resistance are observed before symptom expression of some tree diseases, which can help to establish a certain disease potential hazard rating system. Mechanisms of electrical capacitance and resistance assessing tree vigor, especially in molecule level, still need to be studied and the application criteria of electrical resistance and capacitance need to be established.
