Ni-Al composite coatings were electrodeposited from a modified Watts solution. The electrochemical behavior of the coatings was studied by means of zeta potential analysis, voltammetry and electrochemical impedance sp...Ni-Al composite coatings were electrodeposited from a modified Watts solution. The electrochemical behavior of the coatings was studied by means of zeta potential analysis, voltammetry and electrochemical impedance spectroscopy（EIS）. It was found that the zeta potential of Al particles was-4 m V which is very close to that of Al2O3. Moreover, addition of conductive Al particles into the electrolyte shifted the polarization curve to more negative potentials and loop size of EIS curve increased. It was also demonstrated that the co-deposition behavior of Ni-Al composite coatings obeys the Guglielmi’s model. The results indicate that conductive Al particles behave as the inert particles and confirm the existence of a thin aluminum oxide layer on the surface of aluminum particles.展开更多
Current dependence and stability of the measured resistance value are very important for the accurate measurement of DC standard resistor. In this paper, the volt-ampere （V-I） measurement method has been applied ...Current dependence and stability of the measured resistance value are very important for the accurate measurement of DC standard resistor. In this paper, the volt-ampere （V-I） measurement method has been applied to study the current depend-ence of four different types of standard resistors. Diverse values are obtained through the investigation of their stability at dif-ferent currents. Therefore, the current dependence coefficient （CDC） can be determined for each one of the studied resistors. Research shows CDC depends on the applied current value, the measurement time and the resistor type, as clearly demonstra-ted in this research.展开更多
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
文摘Ni-Al composite coatings were electrodeposited from a modified Watts solution. The electrochemical behavior of the coatings was studied by means of zeta potential analysis, voltammetry and electrochemical impedance spectroscopy（EIS）. It was found that the zeta potential of Al particles was-4 m V which is very close to that of Al2O3. Moreover, addition of conductive Al particles into the electrolyte shifted the polarization curve to more negative potentials and loop size of EIS curve increased. It was also demonstrated that the co-deposition behavior of Ni-Al composite coatings obeys the Guglielmi’s model. The results indicate that conductive Al particles behave as the inert particles and confirm the existence of a thin aluminum oxide layer on the surface of aluminum particles.
文摘Current dependence and stability of the measured resistance value are very important for the accurate measurement of DC standard resistor. In this paper, the volt-ampere （V-I） measurement method has been applied to study the current depend-ence of four different types of standard resistors. Diverse values are obtained through the investigation of their stability at dif-ferent currents. Therefore, the current dependence coefficient （CDC） can be determined for each one of the studied resistors. Research shows CDC depends on the applied current value, the measurement time and the resistor type, as clearly demonstra-ted in this research.
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.
