This article proposes a precise and ecofriendly micromachining technology for aerospace application called electrochemical machining in pure water （PW-ECM）. On the basis of the principles of water dissociation, a se...This article proposes a precise and ecofriendly micromachining technology for aerospace application called electrochemical machining in pure water （PW-ECM）. On the basis of the principles of water dissociation, a series of test setups and tests are devised and performed under different conditions. These tests explain the need for technological conditions realizing PW-ECM, and further explore the technological principles. The results from the tests demonstrate a successful removal of electrolytic slime by means of ultrasonic vibration of the workpiece. To ensure the stability and reliability of PW-ECM process, a new combined machining method of PW-ECM assisted with ultrasonic vibration （PW-ECM/USV） is devised. Trilateral and square cavities and holes as well as a group of English alphabets are worked out on a stainless steel plate. It is confirmed that PW-ECM will be probably an efficient new aviation precision machining method.展开更多
This paper describes pure water making equipment by using applicable datebase, computer languages and drawing software. It gives a general introduction to the systematic designing plan, the division of the different...This paper describes pure water making equipment by using applicable datebase, computer languages and drawing software. It gives a general introduction to the systematic designing plan, the division of the different parts and their functions, and the pure water making technological process.展开更多
Pure water has been characterized for nearly a century, by its dissociation into hydronium （H3O）1＋ and hydroxide （HO）1- ions. As a chemical equilibrium reaction, the equilibrium constant, known as the ion product...Pure water has been characterized for nearly a century, by its dissociation into hydronium （H3O）1＋ and hydroxide （HO）1- ions. As a chemical equilibrium reaction, the equilibrium constant, known as the ion product or the product of the equilibrium concentration of the two ion species, has been extensively measured by chemists over the liquid water temperature and pressure range. The experimental data have been nonlinear least-squares fitted to chemical thermodynamic-based equilibrium equations, which have been accepted as the industrial standard for 35 years. In this study, a new and statistical-physics-based water ion product equation is presented, in which, the ions are the positively charged protons and the negatively charged proton-holes or prohols. Nonlinear least squares fits of our equation to the experimental data in the 0-100℃ pure liquid water range, give a factor of two better precision than the 35-year industrial standard.展开更多
Photocatalytic hydrogen(H_(2))production via water splitting in the absence of sacrificial agents is a promising strategy for producing clean and sustainable hydrogen energy from solar energy.However,the realization o...Photocatalytic hydrogen(H_(2))production via water splitting in the absence of sacrificial agents is a promising strategy for producing clean and sustainable hydrogen energy from solar energy.However,the realization of a photocatalytic pure water splitting system with desirable efficiency is still a huge challenge.Herein,visible light photocatalytic H_(2) production from pure water splitting was successfully achieved using a g-C_(3)N_(4)/CoTiO_(3) S-scheme heterojunction photocatalyst in the absence of sacrificial agents.An optimum hydrogen evolution rate of 118μmol∙h^(−1)∙g^(−1) was reached with the addition of 1.5 wt%CoTiO_(3).The remarkably promoted hydrogen evolution rate was attributed to the intensified light absorption coupled with the synergistic effect of visible light responsive CoTiO_(3),the promoted efficiency in charge separation,and the reserved strong redox capacity induced by the S-scheme charge transfer mechanism.This work provides an alternative to visible light-responding oxidation photocatalysts for the construction of S-scheme heterojunctions and high-efficiency photocatalytic systems for pure water splitting.展开更多
To discover the microscopic mechanism responsible for cavitation nucleation in pure water,nucleation processes in pure water are simulated using the molecular dynamics method.Cavitation nucleation is generated by unif...To discover the microscopic mechanism responsible for cavitation nucleation in pure water,nucleation processes in pure water are simulated using the molecular dynamics method.Cavitation nucleation is generated by uniformly stretching the system under isothermal conditions,and the formation and development of cavitation nuclei are simulated and discussed at the molecular level.The processes of energy,pressure,and density are analyzed,and the tensile strength of the pure water and the critical volume of the bubble nuclei are investigated.The results show that critical states exist in the process of cavitation nucleation.In the critical state,the energy,density,and pressure of the system change abruptly,and a stable cavitation nucleus is produced if the energy barrier is broken and the critical volume is exceeded.System pressure and water density are the key factors in the generation of cavitation nuclei.When the critical state is surpassed,the liquid is completely ruptured,and the volume of the cavitation nucleus rapidly increases to larger than 100 nm^(3);at this point,the surface tension of the bubble dominates the cavitation nucleus,instead of intermolecular forces.The negative critical pressure for bubble nucleation is-198.6 MPa,the corresponding critical volume is 13.84 nm^(3),and the nucleation rate is 2.42×10^(32)m^(-3)·s^(-1)in pure water at 300 K.Temperature has a significant effect on nucleation:as the temperature rises,nucleation thresholds decrease,and cavitation nucleation occurs earlier.展开更多
A novel 212DFDTD method aiming to deal with dispersive media is developed. It is named as 212D(FD)2TD method. The main idea of it is to represent the constitutive equation by a convolution in time domain. Consequently...A novel 212DFDTD method aiming to deal with dispersive media is developed. It is named as 212D(FD)2TD method. The main idea of it is to represent the constitutive equation by a convolution in time domain. Consequently, this newly developed method is used to analyze some of the characteristics of an ideal line antenna in pure water. A good agreement with the former experimented results is obtained.展开更多
Photocatalytic water splitting has emerged as a new frontier for converting solar energy to green H_(2) and value-added chemicals.Nevertheless,great challenges still remain for developing efficient photocatalysts for ...Photocatalytic water splitting has emerged as a new frontier for converting solar energy to green H_(2) and value-added chemicals.Nevertheless,great challenges still remain for developing efficient photocatalysts for pure water splitting without sacrificial agents.In this work,we demonstrate that doping hexagonal ZnIn_(2)S_(4)(ZIS) with Pd single atoms(Pd_(0.03)/ZIS) can serve as a highly efficient photocatalyst for pure water splitting to simultaneously produce H_(2) and H_(2)O_(2) without any sacrificial agents.Results from aberration-corrected high-angle annular dark field scanning transmission electron microscopy,X-ray fine spectroscopy,insitu electron paramagnetic resonance and diffuse Fourier transform infrared spectroscopy reveal that doping ZIS with Pd single atoms facilitates the formation of S vacancies(S_(v)),where the photogenerated electrons can transfer to Pd single atoms,as a result of enhanced separation of electron-hole pairs and improved photocatalytic performance.Impressively,Pd_(0.03)/ZIS displays a stoichiometric ratio of H_(2) and H_(2)O_(2) with the productivity of 1,037.9 and 1,021.4μmol g^(-1)h^(-1),respectively,which has largely outperformed pure ZIS and other reported catalysts for pure water splitting.This work provides an efficient photocatalyst for water splitting to produce H_(2) and H_(2)O_(2),which may attract rapid interest in materials science,chemistry,and heterogeneous catalysis.展开更多
As a versatile energy carrier,H_(2) is considered as one of the most promising sources of clean energy to tackle the current energy crisis and environmental concerns,which can be produced from photocatalytic water spl...As a versatile energy carrier,H_(2) is considered as one of the most promising sources of clean energy to tackle the current energy crisis and environmental concerns,which can be produced from photocatalytic water splitting.However,solar-driven photocatalytic H_(2) production from pure water in the absence of sacrificial reagents remains a great challenge.Herein,we demonstrate that the incorporation of Ru single atoms(SAs)into ZnIn_(2)S_(4)(Ru-ZIS)can enhance the light absorption,reduce the energy barriers for water dissociation,and construct a channel(Ru-S)for separating photogenerated electron−hole pairs,as a result of a significantly enhanced photocatalytic water splitting process.Impressively,the productivity of H_(2) reaches 735.2μmol g^(-1) h^(-1) under visible light irradiation in the absence of sacrificial agents.The apparent quantum efficiency(AQE)for H_(2) evolution reaches 7.5% at 420 nm,with a solarto-hydrogen(STH)efficiency of 0.58%,which is much higher than the value of natural synthetic plants(~0.10%).Moreover,Ru-ZIS exhibits steady productivity of H_(2) even after exposure to ambient conditions for 330 days.This work provides a unique strategy for constructing charge transfer channels to promote the separation of photogenerated electron−hole pairs,which may motivate the fundamental researches on catalyst design for photocatalysis and beyond.展开更多
基金Aeronautical Science Foundation of China (02H52049)
文摘This article proposes a precise and ecofriendly micromachining technology for aerospace application called electrochemical machining in pure water （PW-ECM）. On the basis of the principles of water dissociation, a series of test setups and tests are devised and performed under different conditions. These tests explain the need for technological conditions realizing PW-ECM, and further explore the technological principles. The results from the tests demonstrate a successful removal of electrolytic slime by means of ultrasonic vibration of the workpiece. To ensure the stability and reliability of PW-ECM process, a new combined machining method of PW-ECM assisted with ultrasonic vibration （PW-ECM/USV） is devised. Trilateral and square cavities and holes as well as a group of English alphabets are worked out on a stainless steel plate. It is confirmed that PW-ECM will be probably an efficient new aviation precision machining method.
文摘This paper describes pure water making equipment by using applicable datebase, computer languages and drawing software. It gives a general introduction to the systematic designing plan, the division of the different parts and their functions, and the pure water making technological process.
文摘Pure water has been characterized for nearly a century, by its dissociation into hydronium （H3O）1＋ and hydroxide （HO）1- ions. As a chemical equilibrium reaction, the equilibrium constant, known as the ion product or the product of the equilibrium concentration of the two ion species, has been extensively measured by chemists over the liquid water temperature and pressure range. The experimental data have been nonlinear least-squares fitted to chemical thermodynamic-based equilibrium equations, which have been accepted as the industrial standard for 35 years. In this study, a new and statistical-physics-based water ion product equation is presented, in which, the ions are the positively charged protons and the negatively charged proton-holes or prohols. Nonlinear least squares fits of our equation to the experimental data in the 0-100℃ pure liquid water range, give a factor of two better precision than the 35-year industrial standard.
文摘Photocatalytic hydrogen(H_(2))production via water splitting in the absence of sacrificial agents is a promising strategy for producing clean and sustainable hydrogen energy from solar energy.However,the realization of a photocatalytic pure water splitting system with desirable efficiency is still a huge challenge.Herein,visible light photocatalytic H_(2) production from pure water splitting was successfully achieved using a g-C_(3)N_(4)/CoTiO_(3) S-scheme heterojunction photocatalyst in the absence of sacrificial agents.An optimum hydrogen evolution rate of 118μmol∙h^(−1)∙g^(−1) was reached with the addition of 1.5 wt%CoTiO_(3).The remarkably promoted hydrogen evolution rate was attributed to the intensified light absorption coupled with the synergistic effect of visible light responsive CoTiO_(3),the promoted efficiency in charge separation,and the reserved strong redox capacity induced by the S-scheme charge transfer mechanism.This work provides an alternative to visible light-responding oxidation photocatalysts for the construction of S-scheme heterojunctions and high-efficiency photocatalytic systems for pure water splitting.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51779187 and 51873160)。
文摘To discover the microscopic mechanism responsible for cavitation nucleation in pure water,nucleation processes in pure water are simulated using the molecular dynamics method.Cavitation nucleation is generated by uniformly stretching the system under isothermal conditions,and the formation and development of cavitation nuclei are simulated and discussed at the molecular level.The processes of energy,pressure,and density are analyzed,and the tensile strength of the pure water and the critical volume of the bubble nuclei are investigated.The results show that critical states exist in the process of cavitation nucleation.In the critical state,the energy,density,and pressure of the system change abruptly,and a stable cavitation nucleus is produced if the energy barrier is broken and the critical volume is exceeded.System pressure and water density are the key factors in the generation of cavitation nuclei.When the critical state is surpassed,the liquid is completely ruptured,and the volume of the cavitation nucleus rapidly increases to larger than 100 nm^(3);at this point,the surface tension of the bubble dominates the cavitation nucleus,instead of intermolecular forces.The negative critical pressure for bubble nucleation is-198.6 MPa,the corresponding critical volume is 13.84 nm^(3),and the nucleation rate is 2.42×10^(32)m^(-3)·s^(-1)in pure water at 300 K.Temperature has a significant effect on nucleation:as the temperature rises,nucleation thresholds decrease,and cavitation nucleation occurs earlier.
文摘A novel 212DFDTD method aiming to deal with dispersive media is developed. It is named as 212D(FD)2TD method. The main idea of it is to represent the constitutive equation by a convolution in time domain. Consequently, this newly developed method is used to analyze some of the characteristics of an ideal line antenna in pure water. A good agreement with the former experimented results is obtained.
基金financially supported by the National Key R&D Program of China(2020YFB1505802)the Ministry of Science and Technology of China(2017YFA0208200)+2 种基金the National Natural Science Foundation of China(22025108,U21A20327,22121001)Guangdong Provincial Natural Science Fund for Distinguished Young Scholars(2021B1515020081)the start-up support from Xiamen University。
文摘Photocatalytic water splitting has emerged as a new frontier for converting solar energy to green H_(2) and value-added chemicals.Nevertheless,great challenges still remain for developing efficient photocatalysts for pure water splitting without sacrificial agents.In this work,we demonstrate that doping hexagonal ZnIn_(2)S_(4)(ZIS) with Pd single atoms(Pd_(0.03)/ZIS) can serve as a highly efficient photocatalyst for pure water splitting to simultaneously produce H_(2) and H_(2)O_(2) without any sacrificial agents.Results from aberration-corrected high-angle annular dark field scanning transmission electron microscopy,X-ray fine spectroscopy,insitu electron paramagnetic resonance and diffuse Fourier transform infrared spectroscopy reveal that doping ZIS with Pd single atoms facilitates the formation of S vacancies(S_(v)),where the photogenerated electrons can transfer to Pd single atoms,as a result of enhanced separation of electron-hole pairs and improved photocatalytic performance.Impressively,Pd_(0.03)/ZIS displays a stoichiometric ratio of H_(2) and H_(2)O_(2) with the productivity of 1,037.9 and 1,021.4μmol g^(-1)h^(-1),respectively,which has largely outperformed pure ZIS and other reported catalysts for pure water splitting.This work provides an efficient photocatalyst for water splitting to produce H_(2) and H_(2)O_(2),which may attract rapid interest in materials science,chemistry,and heterogeneous catalysis.
基金financially supported by the National Key R&D Program of China(2020YFB1505802)the Ministry of Science and Technology(2017YFA0208200)+1 种基金the National Natural Science Foundation of China(22025108,U21A20327,and 22121001)the start-up funding from Xiamen University.
文摘As a versatile energy carrier,H_(2) is considered as one of the most promising sources of clean energy to tackle the current energy crisis and environmental concerns,which can be produced from photocatalytic water splitting.However,solar-driven photocatalytic H_(2) production from pure water in the absence of sacrificial reagents remains a great challenge.Herein,we demonstrate that the incorporation of Ru single atoms(SAs)into ZnIn_(2)S_(4)(Ru-ZIS)can enhance the light absorption,reduce the energy barriers for water dissociation,and construct a channel(Ru-S)for separating photogenerated electron−hole pairs,as a result of a significantly enhanced photocatalytic water splitting process.Impressively,the productivity of H_(2) reaches 735.2μmol g^(-1) h^(-1) under visible light irradiation in the absence of sacrificial agents.The apparent quantum efficiency(AQE)for H_(2) evolution reaches 7.5% at 420 nm,with a solarto-hydrogen(STH)efficiency of 0.58%,which is much higher than the value of natural synthetic plants(~0.10%).Moreover,Ru-ZIS exhibits steady productivity of H_(2) even after exposure to ambient conditions for 330 days.This work provides a unique strategy for constructing charge transfer channels to promote the separation of photogenerated electron−hole pairs,which may motivate the fundamental researches on catalyst design for photocatalysis and beyond.
