The electric double layer with the transmission of particles was presented based on the principle of electrochemistry.In accordance with this theory,the cavitation catalysis removal mechanism of ultrasonic-pulse elect...The electric double layer with the transmission of particles was presented based on the principle of electrochemistry.In accordance with this theory,the cavitation catalysis removal mechanism of ultrasonic-pulse electrochemical compound machining(UPECM) based on particles was proposed.The removal mechanism was a particular focus and was thus validated by experiments.The principles and experiments of UPECM were introduced,and the removal model of the UPECM based on the principles of UPECM was established.Furthermore,the effects of the material removal rate for the main processing parameters,including the particles size,the ultrasonic vibration amplitude,the pulse voltage and the minimum machining gap between the tool and the workpiece,were also studied through UPECM.The results show that the particles promote ultrasonic-pulse electrochemical compound machining and thus act as the catalyzer of UPECM.The results also indicate that the processing speed,machining accuracy and surface quality can be improved under UPECM compound machining.展开更多
To investigate the interactions of oppositely charged sites on the surfaces of variable-charge soil particles with cations and anions, and to evaluate the mean Gibbs free binding and adsorption energies of various cat...To investigate the interactions of oppositely charged sites on the surfaces of variable-charge soil particles with cations and anions, and to evaluate the mean Gibbs free binding and adsorption energies of various cations on particles of red soil and latosol, clay fractions smaller than 2 μm were separated from samples of the two variable-charge soils. Ferric oxides were removed from part of the clay fractions, which were then saturated with various chlorides （NaC1, KCl, CaCl2, CdCl2 or LaCl3）. Electrical conductivities （EC） of dilute suspensions of the original and of the iron oxides-free clay fractions in deionized water were measured with the SHP-2 short high-voltage pulse apparatus, which enables measurement of the Wien effect at field strengths （E） from 14 to 250 kV cm^-1. The Wien effect （EC-E） curves revealed EC increases of red soil suspensions between 14 and 200 kV cm^-1, of 8.3, 8.4, 12.1, 5.9, and 1.2 μS cm^-1 for NaCl, KCl, CaCl2, CdCl2, and LaCl3, respectively, reflecting the differing interactions with the various cations and chloride. The EC increments with the iron-free red soil suspensions were higher, being 29.7, 17.2, and 15.3 μS cm^-1 for NaCl, CaCl2, and CdCl2, respectively. In the natural latosol suspensions the EC increments were practically zero, whereas in the iron-free fractions there were significant EC increments of 10.3, 5.7, 5.0, and 1.6μS cm^-1 for NaCl, CaCl2, CdCl2, and LaCl3, respectively.展开更多
The dielectric properties between in-particle/water interface and bulk solution are significantly different,which are ignored in the theories of surface potential estimation.The analytical expressions of surface poten...The dielectric properties between in-particle/water interface and bulk solution are significantly different,which are ignored in the theories of surface potential estimation.The analytical expressions of surface potential considering the dielectric saturation were derived in mixed electrolytes based on the nonlinear Poisson-Boltzmann equation.The surface potentials calculated from the approximate analytical and exact numerical solutions agreed with each other for a wide range of surface charge densities and ion concentrations.The effects of dielectric saturation became important for surface charge densities larger than 0.30 C/m^2.The analytical models of surface potential in different mixed electrolytes were valid based on original Poisson-Boltzmann equation for surface charge densities smaller than 0.30 C/m^2.The analytical model of surface potential considering the dielectric saturation for low surface charge density can return to the result of classical Poisson-Boltzmann theory.The obtained surface potential in this study can correctly predict the adsorption selectivity between monovalent and bivalent counterions.展开更多
Surface charge distribution of particles is the fundamental problem for adsorption and desorption between sediment and contaminant. In this paper, we take quartz sand for example to measure its micro-morphology and su...Surface charge distribution of particles is the fundamental problem for adsorption and desorption between sediment and contaminant. In this paper, we take quartz sand for example to measure its micro-morphology and surface charge distribution using the phase mode of the electrical force microscope. Then the statistical relation of micro-morphology and surface charge distribution is obtained. Results show that quartz sand possesses complex surface morphology, which has great impact on the charge distribution. Positive and negative charges mostly concentrate on the saddle, convex and concave parts of the surface, while distribute less in the groove, ridge and flat parts. This experiment provides a new method for understanding the process of flocculation in coastal and estuarine zone.展开更多
Semiconductor-based photocatalysis for efficient solar energy conversion is an ideal strategy to tackle the growing global energy and environmental crisis.However,the development of photocatalysis is still limited by ...Semiconductor-based photocatalysis for efficient solar energy conversion is an ideal strategy to tackle the growing global energy and environmental crisis.However,the development of photocatalysis is still limited by problems such as low utilization of visible light,low efficiency of charge transfer and separation,and insufficient reactive sites.Herein,Au nanoparticles(NPs)were deposited on the surface of Bi_(2)WO_(6)by a one-step reduction method,which simultaneously induced the formation of oxygen vacancies(OVs)on the surface of Bi_(2)WO_(6).The OVs concentration is found to be increased with the increase of Au loading.Au NPs and OVs improve the light absorption and facilitate the separation and transport of the photogenerated carriers.In addition,OVs act synergistically with the nearby metal active sites to optimize the adsorption energy of reactants on the catalyst surface,changing the adsorption form of CO_(2)molecules on the catalyst surface.The as-synthesized photocatalyst achieved a photocatalytic performance of up to 34.8μmol g^(−1)h^(−1)of CO_(2)reduction to CO without sacrificial agent in a gas-solid system,which is 9.4 times higher than that of the pristine Bi_(2)WO_(6).This work may further deepen our understanding on the relationship between metal NPs and OVs,and their combined role in photocatalysis.展开更多
Printing is a method of additive manufacturing that can reduce material costs and environmental contamination during the fabrication process.Ag ink is commonly used in printed electronics,such as interconnects,inducto...Printing is a method of additive manufacturing that can reduce material costs and environmental contamination during the fabrication process.Ag ink is commonly used in printed electronics,such as interconnects,inductors,and antennas.However,the high cost of noble Ag restricts its massive applications.To reduce the cost of the state-of-the-art Ag ink and realize large-scale manufacturing,we develop a molecule-bridged graphene/Ag(MB-G/A)composite to produce highly conductive and cost-effective paperbased electronics.Graphene can be used to substitute part of Ag nanoparticles to reduce costs,form a conducive percolation network,and retain a reasonable level of conductivity.We adopt cysteamine as a molecular linker,because it anchors on the surface of graphene via the diazonium reaction.Additionally,the thiol functional group on the other end of cysteamine can bond to a Ag atom,forming a molecular bridge between graphene and Ag and promoting electron transport between Ag and graphene.As a result,the maximum conductivity of MB-G/A inks can reach 2.0×10^(5)S m^(−1),enabling their successful application in various printable electronics.In addition,the optimum MB-G/A ink costs less than half as much as pure Ag inks,showing the great potential of MB-G/A ink in commercial electronic devices.展开更多
基金Project(51275116)supported by the National Natural Science Foundation of ChinaProject(2012ZE77010)supported by the Aero Science Foundation of ChinaProject(LBH-Q11090)supported by the Postdoctoral Science Research Development Foundation of Heilongjiang Province,China
文摘The electric double layer with the transmission of particles was presented based on the principle of electrochemistry.In accordance with this theory,the cavitation catalysis removal mechanism of ultrasonic-pulse electrochemical compound machining(UPECM) based on particles was proposed.The removal mechanism was a particular focus and was thus validated by experiments.The principles and experiments of UPECM were introduced,and the removal model of the UPECM based on the principles of UPECM was established.Furthermore,the effects of the material removal rate for the main processing parameters,including the particles size,the ultrasonic vibration amplitude,the pulse voltage and the minimum machining gap between the tool and the workpiece,were also studied through UPECM.The results show that the particles promote ultrasonic-pulse electrochemical compound machining and thus act as the catalyzer of UPECM.The results also indicate that the processing speed,machining accuracy and surface quality can be improved under UPECM compound machining.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.ISSASIP 0718)the National Natural Science Foundation of China (Nos.40401030 and 40871114)
文摘To investigate the interactions of oppositely charged sites on the surfaces of variable-charge soil particles with cations and anions, and to evaluate the mean Gibbs free binding and adsorption energies of various cations on particles of red soil and latosol, clay fractions smaller than 2 μm were separated from samples of the two variable-charge soils. Ferric oxides were removed from part of the clay fractions, which were then saturated with various chlorides （NaC1, KCl, CaCl2, CdCl2 or LaCl3）. Electrical conductivities （EC） of dilute suspensions of the original and of the iron oxides-free clay fractions in deionized water were measured with the SHP-2 short high-voltage pulse apparatus, which enables measurement of the Wien effect at field strengths （E） from 14 to 250 kV cm^-1. The Wien effect （EC-E） curves revealed EC increases of red soil suspensions between 14 and 200 kV cm^-1, of 8.3, 8.4, 12.1, 5.9, and 1.2 μS cm^-1 for NaCl, KCl, CaCl2, CdCl2, and LaCl3, respectively, reflecting the differing interactions with the various cations and chloride. The EC increments with the iron-free red soil suspensions were higher, being 29.7, 17.2, and 15.3 μS cm^-1 for NaCl, CaCl2, and CdCl2, respectively. In the natural latosol suspensions the EC increments were practically zero, whereas in the iron-free fractions there were significant EC increments of 10.3, 5.7, 5.0, and 1.6μS cm^-1 for NaCl, CaCl2, CdCl2, and LaCl3, respectively.
基金supported by the National Natural Science Foundation of China(No.41877026)the Natural Science Foundation Project of CQ CSTC(cstc2018jcyj AX0318)the“Guangjiong”Project of Southwest University,China(201716)。
文摘The dielectric properties between in-particle/water interface and bulk solution are significantly different,which are ignored in the theories of surface potential estimation.The analytical expressions of surface potential considering the dielectric saturation were derived in mixed electrolytes based on the nonlinear Poisson-Boltzmann equation.The surface potentials calculated from the approximate analytical and exact numerical solutions agreed with each other for a wide range of surface charge densities and ion concentrations.The effects of dielectric saturation became important for surface charge densities larger than 0.30 C/m^2.The analytical models of surface potential in different mixed electrolytes were valid based on original Poisson-Boltzmann equation for surface charge densities smaller than 0.30 C/m^2.The analytical model of surface potential considering the dielectric saturation for low surface charge density can return to the result of classical Poisson-Boltzmann theory.The obtained surface potential in this study can correctly predict the adsorption selectivity between monovalent and bivalent counterions.
基金supported by the National Natural Science Foundation of China (Grant No. 50909095)Chinese Universities Scientific Fund (Grant No. 2011JS131)
文摘Surface charge distribution of particles is the fundamental problem for adsorption and desorption between sediment and contaminant. In this paper, we take quartz sand for example to measure its micro-morphology and surface charge distribution using the phase mode of the electrical force microscope. Then the statistical relation of micro-morphology and surface charge distribution is obtained. Results show that quartz sand possesses complex surface morphology, which has great impact on the charge distribution. Positive and negative charges mostly concentrate on the saddle, convex and concave parts of the surface, while distribute less in the groove, ridge and flat parts. This experiment provides a new method for understanding the process of flocculation in coastal and estuarine zone.
基金the National Natural Science Foundations of China(51972288 and 51672258)the Fundamental Research Funds for the Central Universities(2652018287)the 2021 Graduate Innovation Fund Project of China University of Geosciences,Beijing(ZY2021YC006).
文摘Semiconductor-based photocatalysis for efficient solar energy conversion is an ideal strategy to tackle the growing global energy and environmental crisis.However,the development of photocatalysis is still limited by problems such as low utilization of visible light,low efficiency of charge transfer and separation,and insufficient reactive sites.Herein,Au nanoparticles(NPs)were deposited on the surface of Bi_(2)WO_(6)by a one-step reduction method,which simultaneously induced the formation of oxygen vacancies(OVs)on the surface of Bi_(2)WO_(6).The OVs concentration is found to be increased with the increase of Au loading.Au NPs and OVs improve the light absorption and facilitate the separation and transport of the photogenerated carriers.In addition,OVs act synergistically with the nearby metal active sites to optimize the adsorption energy of reactants on the catalyst surface,changing the adsorption form of CO_(2)molecules on the catalyst surface.The as-synthesized photocatalyst achieved a photocatalytic performance of up to 34.8μmol g^(−1)h^(−1)of CO_(2)reduction to CO without sacrificial agent in a gas-solid system,which is 9.4 times higher than that of the pristine Bi_(2)WO_(6).This work may further deepen our understanding on the relationship between metal NPs and OVs,and their combined role in photocatalysis.
基金financially supported by Hong Kong Scholars Program(XJ2019025)The Hong Kong Polytechnic University(CD42)Shenzhen Science and Technology Innovation Commission(JCYJ20180507183424383)。
文摘Printing is a method of additive manufacturing that can reduce material costs and environmental contamination during the fabrication process.Ag ink is commonly used in printed electronics,such as interconnects,inductors,and antennas.However,the high cost of noble Ag restricts its massive applications.To reduce the cost of the state-of-the-art Ag ink and realize large-scale manufacturing,we develop a molecule-bridged graphene/Ag(MB-G/A)composite to produce highly conductive and cost-effective paperbased electronics.Graphene can be used to substitute part of Ag nanoparticles to reduce costs,form a conducive percolation network,and retain a reasonable level of conductivity.We adopt cysteamine as a molecular linker,because it anchors on the surface of graphene via the diazonium reaction.Additionally,the thiol functional group on the other end of cysteamine can bond to a Ag atom,forming a molecular bridge between graphene and Ag and promoting electron transport between Ag and graphene.As a result,the maximum conductivity of MB-G/A inks can reach 2.0×10^(5)S m^(−1),enabling their successful application in various printable electronics.In addition,the optimum MB-G/A ink costs less than half as much as pure Ag inks,showing the great potential of MB-G/A ink in commercial electronic devices.
