| 1. |
- Ji, Linan, et al.
(author)
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An overview of the progress of new working pairs in absorption heat pumps
- 2023
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In: Energy Reports. - : Elsevier Ltd. - 2352-4847. ; 9, s. 703-729
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Research review (peer-reviewed)abstract
- Absorption heat pumps have emerged as a potential tool to address the energy crisis because of their ability to utilize low-grade heat. The performance of an absorption heat pump largely depends on the efficiency of the working pair to operate at the source temperature. The commercialized working pairs H2O/LiBr and NH3/H2O linger with operational and economic issues. Several binary/ternary combinations were tested among water, ammonia, salt, alcohols, hydrocarbons, and ionic liquids (ILs) in quest of the potential working pairs. The last decade has witnessed a stupendous surge in IL-based working pairs because of their several advantageous properties over the traditional solvents. The present review encompasses the research progress on various working pairs, in particular, their properties, modeling and correlation results, and coefficient of performance (COP) values.
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| 2. |
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| 3. |
- Ji, Xiaoyan, et al.
(author)
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Thermodynamic and dynamic investigation for CO2 storage in deep saline aquifers
- 2011
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In: Proceedings of the World Renewable Energy Congress 2011 (WREC 2011). - Linköping : Linköping University Electronic Press.
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Conference paper (peer-reviewed)abstract
- Thermodynamic and dynamic investigations are needed to study the sequestration capacity, CO2 leakage, and environmental impacts. The results of the phase equilibrium and densities for CO2-sequestration related subsystems obtained from the proposed thermodynamic model on the basis of statistical associating fluid theory equation of state were summarized. Based on the equilibrium thermodynamics, preliminary kinetics results were also illustrated with chemical potential gradient as the driving force. The proposed thermodynamic model is promising to represent phase equilibrium and thermodynamic properties for CO2-sequestration related systems, i.e. CO2-(H2S)-H2O-ions (such as Na+, K+, Ca2+, Mg2+, Cl-, CO32-), and the implementation of thermodynamic model into kinetics model to adjust the non-ideality of species is vital because of the high pressure for the investigation of the sequestration process.
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| 4. |
- Ji, Yuanhui, et al.
(author)
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Coupling mass transfer with mineral reactions to investigate CO2 sequestration in saline aquifers with non-equilibrium thermodynamics
- 2011
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In: Proceedings of the World Renewable Energy Congress 2011 (WREC 2011). - : Linköping University Electronic Press.
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Conference paper (peer-reviewed)abstract
- The coupling behaviors of mass transfer of aqueous CO2 with mineral reactions of aqueous CO2 with rock anorthite are investigated by chemical potential gradient and concentration gradient models, respectively. SAFT1-RPM is used to calculate the fugacity of CO2 in brine. The effective diffusion coefficients of CO2 are obtained based on the experimental kinetic data reported in literature. The calculation results by the two models and for two cases (mass transfer only and coupling mass transfer with mineral reaction) are compared. The results show that there are considerable discrepancies for the concentration distribution with distance by the concentration gradient and chemical potential gradient models, which implies the importance of consideration of the non-ideality. And the concentrations of aqueous CO2 at different distances by the concentration gradient model are higher and further than that by the chemical potential gradient model. The mineral reaction plays a considerable role for the CO2 geological sequestration when the time scale reaches 10 years for the anorthite case.
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| 5. |
- Ji, YuanHui, et al.
(author)
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Modeling mass transfer of CO2 in brine at high pressures by chemical potential gradient
- 2013
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In: Science China Chemistry. - : Springer Science and Business Media LLC. - 1674-7291 .- 1869-1870. ; 56:6, s. 821-830
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Journal article (peer-reviewed)abstract
- To investigate long-term CO2 behavior in geological formations and quantification of possible CO2 leaks, it is crucial to investigate the potential mobility of CO2 dissolved in brines over a wide range of spatial and temporal scales and density distributions in geological media. In this work, the mass transfer of aqueous CO2 in brines has been investigated by means of a chemical potential gradient model based on non-equilibrium thermodynamics in which the statistical associating fluid theory equation of state was used to calculate the fugacity coefficient of CO2 in brine. The investigation shows that the interfacial concentration of aqueous CO2 and the corresponding density both increase with increasing pressure and decreasing temperature; the effective diffusion coefficients decrease initially and then increase with increasing pressure; and the density of the CO2-disolved brines increases with decreasing CO2 pressure in the CO2 dissolution process. The aqueous CO2 concentration profiles obtained by the chemical potential gradient model are considerably different from those obtained by the concentration gradient model, which shows the importance of considering non-ideality, especially when the pressure is high.
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| 6. |
- Ji, Yuanhui, et al.
(author)
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Modeling of specific structure crystallization coupling with dissolution
- 2010
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In: Frontiers of Chemical Science and Engineering. - : Springer Science and Business Media LLC. - 1673-7369. ; 4:1, s. 52-56
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Journal article (peer-reviewed)abstract
- In this paper, the research framework for specific structure crystallization modeling has been proposed in which four steps are required in order to investigate the rigorous crystallization modeling by thermodynamics. The first is the activity coefficient model of the solution, the second is Solid-Liquid equilibrium, the third and fourth are the dissolution and crystallization kinetics modeling, respectively. Our investigations show that the mechanisms of complex structure formation and microphase transition can be analyzed by combining the dissolution and crystallization kinetics modeling. Moreover, the formation mechanism of the porous KCl has been analyzed, which may provide a reference for the porous structure formation in the advanced material synthesis
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| 7. |
- Ji, Yuanhui, et al.
(author)
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Modeling the transport of CO2 in porous media with aqueous solutions by Gibbs free energy gradient
- 2010
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Conference paper (other academic/artistic)abstract
- The concentration of CO2 in atmosphere has been increasing greatly because of the fossil fuel combustion, which leads to a significant climate changes. CO2 is one of the most important greenhouse gases being responsible for about 64% of the enhanced "greenhouse effect" [1], and the disposal of anthropogenic CO2 has become an important issue of worldwide concern. Geological sequestration, generally refers to the injection of CO2 into deep geological formations such as deep saline aquifers, depleted hydrocarbon reservoirs or deep coalbeds, is attracting great attention [2] because of the large capacity and long residence time [3]. To predict the sequestration potential, to study the long-term behavior of CO2, and to estimate the potential for CO2 leakage in the geologic reservoirs, it is necessary to study the transport rate of CO2 in porous media with aqueous solutions. In the present work, the transport rate of CO2 in porous media with aqueous solutions is described and predicted by the Gibbs free energy gradient modeling based on linear nonequilibrium thermodynamics, and the Statistical Associating Fluid Theory equation of state is used to calculate the Gibbs free energy of the components in the investigated systems. The effects of temperature and pressure are analyzed.
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| 8. |
- Ji, Yuanhui, et al.
(author)
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Modelling of mass transfer coupling with crystallization kinetics in microscale
- 2010
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In: Chemical Engineering Science. - : Elsevier BV. - 0009-2509 .- 1873-4405. ; 65:9, s. 2649-2655
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Journal article (peer-reviewed)abstract
- Microstructure technologies have attracted interests in chemistry, chemical engineering, and biotechnology. To investigate the mass transfer of ions and crystallization of crystals in microscale and then to explain the formation mechanism of the porous structure materials, a microscale mathematical model for mass transfer processes coupling with local reactions is proposed in which the chemical potential gradient Δμ is used as the driving force to avoid the discontinuity of the kinetics equations in the micro-channels. Meanwhile, the dissolution kinetics of KCl at 298.15 K is measured to determine the dissolution rate constant kd and the average area of crystals Ac. The investigation for the fractional crystallization process of carnallite shows that the calculated mixing time versus channel width agree with the Einstein diffusion equation, which validates that the model can be used to describe the ion diffusion very well. Meanwhile, to have an accurate Δμ of KCl, in the channel width of or narrower than 2.0×10-6 m, it is enough to consider the diffusion only, while in the channel width of or wider than 2.0×10-5 m, diffusion should be coupled with reaction. The investigation also shows the vital of the consideration of the ionic activity coefficient for the investigated systems in micron scales. Moreover, the new formation mechanism of the porous structures in the inorganic material fabrication will be proposed from the process simulation for the synthesis of porous KCl, which will provide a reference for the porous structure formation in the advanced inorganic material synthesis.
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| 9. |
- Ji, Yuanhui, et al.
(author)
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Progress in the study on the phase equilibria of the CO2-H2O and CO2-H2O-NaCl systems
- 2007
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In: Chinese Journal of Chemical Engineering. - 1004-9541 .- 2210-321X. ; 15:3, s. 439-448
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Journal article (peer-reviewed)abstract
- To study the feasibility of CO2 geological sequestration, it is needed to understand the complicated multiple-phase equilibrium and the densities of aqueous solution with CO2 and multi-ions under wide geological conditions (273.15-473.15 K, 0-60 MPa), which are also essential for designing separation equipments in chemical or oil-related industries. For this purpose, studies on the relevant phase equilibria and densities are reviewed and analyzed and the method to improve or modify the existing model is suggested in order to obtain more reliable predictions in a wide temperature and pressure range. Besides, three different models (the electrolyte non random two-liquid (ELECNRTL), the electrolyte NRTL combining with Helgeson model (ENRTL-HG), Pitzer activity coefficient model combining with Helgeson model (PITZ-HG)) are used to calculate the vapor-liquid phase equilibrium of CO2-H2O and CO2-H2O-NaCl systems. For CO2-H2O system, the calculation results agree with the experimental data very well at low and medium pressure (0-20 MPa), but there are great discrepancies above 20 MPa. For the water content at 473.15 K, the calculated results agree with the experimental data quite well. For the CO2-H2O-NaCl system, the PITZ-HG model show better results than ELECNRTL and ENRTL-HG models at the NaCl concentration of 0.52 mol•L-1. Bur for the NaCl concentration of 3.997 mol•L-1, using the ELECNRTL and ENRTL-HG models gives better results than using the PITZ-HG model. It is shown that available experimental data and the thermodynamic calculations can satisfy the needs of the calculation of the sequestration capacity in the temperature and pressure range for disposal of CO2 in deep saline aquifers. More experimental data and more accurate thermodynamic calculations are needed in high temperature and pressure ranges (above 398.15 K and 31.5 MPa).
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| 10. |
- Ji, Yuanhui, et al.
(author)
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Thermodynamic analysis on the mineralization of trace organic contaminants with oxidants in advanced oxidation processes
- 2009
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In: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 48:23, s. 10728-10733
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Journal article (peer-reviewed)abstract
- There is a growing demand for the efficient treatment of organic polluted wastewaters by advanced oxidation processes (AOPs) which calls for the determination of the mineralization order of ease for the organic contaminants with oxidants. The mineralization abilities of organic contaminants in AOPs are investigated in this work. Photocatalytic experiments for three representative organic contaminants are carried out, and their corresponding reaction rates are determined experimentally. Meanwhile, molar Gibbs free energy changes Delta(r)G(m)degrees for the reactions of 31 organic contaminants (10 chlorinated hydrocarbons, four brominated hydrocarbons, I I aromatic hydrocarbons and their derivatives, three chloroacetic acid, and three chloroacetyl chloride) with oxidants of (OH)-O-center dot, H2O2, O-center dot(-), O-3, and O-2 are calculated, and the mineralization order of ease is determined theoretically on the basis of Delta(r)G(m)degrees. The agreement of the theoretical and experimental mineralization abilities for most of the organic contaminants investigated implies the reliability of the determination of the mineralization ability from the magnitude of Delta(r)G(m)degrees for the mineralization of trace organic contaminants. Results also show that for most of the organic contaminants studied, the mineralization abilities are (OH)-O-center dot > H2O2 > O-center dot(-) > O-3 > O-2, and the mineralization ability of the organic contaminants depends on not only the oxidants but also the structure and properties of the organic contaminants themselves, and the degradation reaction products.
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| 11. |
- Ji, Yuanhui, et al.
(author)
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Thermodynamic study on the reactivity of trace organic contaminant with the hydroxyl radicals in waters by advanced oxidation processes
- 2009
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In: Fluid Phase Equilibria. - : Elsevier BV. - 0378-3812 .- 1879-0224. ; 277:1, s. 15-19
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Journal article (peer-reviewed)abstract
- This paper is to investigate the degradation abilities of various chlorinated aliphatics, benzene and its derivatives in order to treat organic polluted wastewaters efficiently by advanced oxidation processes (AOPs). A thermodynamic method is proposed to calculate the standard molar Gibbs energy of formation for aqueous organic species. Using the method proposed, the standard molar Gibbs energies of formation for 31 aqueous organic species are obtained. Moreover, the molar Gibbs energy change of reaction Δr Gm0 for the organic species with hydroxyl radicals is calculated from the standard molar Gibbs energy of formation for aqueous organic species to determine the degradation order of ease for the organic species. New photocatalytic experiments are carried out for the model verification. The calculation results of the model agree with the available and new experimental results. This work shows that the thermodynamics of the degradation reaction for the organic pollutants in AOPs can find the corresponding relationships with the degradation reaction rate by experimental measurements. The work in this paper represents a success of thermodynamics for the application in environmental area.
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| 12. |
- Lu, XiaoHua, et al.
(author)
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Methodology of non-equilibrium thermodynamics for kinetics research of CO2 capture by ionic liquids
- 2012
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In: Science in China Series B. - : Springer Science and Business Media LLC. - 1674-7291 .- 1869-1870. ; 55:6, s. 1079-1091
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Research review (peer-reviewed)abstract
- In this paper, the methodology of non-equilibrium thermodynamics is introduced for kinetics research of CO 2 capture by ionic liquids, and the following three key scientific problems are proposed to apply the methodology in kinetics research of CO 2 capture by ionic liquids: reliable thermodynamic models, interfacial transport rate description and accurate experimental flux. The obtaining of accurate experimental flux requires reliable experimental kinetics data and the effective transport area in the CO 2 capture process by ionic liquids. Research advances in the three key scientific problems are reviewed systematically and further work is analyzed. Finally, perspectives of non-equilibrium thermodynamic research of the kinetics of CO 2 capture by ionic liquids are proposed.
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| 13. |
- Shen, Gulou, et al.
(author)
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Partition and selectivity of electrolytes in cylindrical nanopores with heterogeneous surface charge
- 2021
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In: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 340
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Journal article (peer-reviewed)abstract
- In this work, ion partitioning and selectivity in cylindrical nanopores with heterogeneous surface charges at equilibrium with reservoirs are investigated by a two-dimensional (2D) classical density functional theory (DFT). We present an efficient numerical method for the large 2D system in which the fast Hankel transform and fast Fourier transform are used to calculate convolution integrals, and a hybrid method of Picard iteration and Anderson mixing is used to solve the Euler-Lagrange equations. The performance of the 2D DFT is tested by calculating the profiles of a model electrolyte in long homogeneous cylindrical nanopores. The profiles from the 2D DFT model matches well with those from a 1D DFT, and the computing time of the hybrid iteration algorithm is six times shorter than that of pure Picard iteration. We apply the model to electrolytes in cylindrical nanopores with heterogeneous surface charges. It is found that the ion adsorption and selectivity are strongly affected by the surface charge pattern, the magnitude of the surface charge, the size of charged domains on the surface, and the pore size.
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| 14. |
- Wu, Nanhua
(author)
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Molecular Thermodynamic Models for Nano-Micro Fluid/Solid Interfaces
- 2020
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Doctoral thesis (other academic/artistic)abstract
- Introducing materials with large interfaces to enhance process performance has become a feature of advanced chemical engineering, where the research focus has been changed from the traditional ideal isotropic fluid in the bulk phase to the highly non-ideal anisotropic confined fluid on the nano-micro interfaces, owing to the strong and asymmetric interactions between the complex fluids (supported metal nanoparticles, ionic liquids, proteins, etc.) and the sophisticated solid-surface (roughness, electrostatic effects, chemical heterogeneities, etc.). The traditional theories cannot be used to accurately describe the properties of the fluids at the complex solid-surfaces, due to the lack of considering molecular interactions between the fluid and solid-surface, and establishing new models is essential.In this thesis, a generalized interfacial molecular thermodynamic model was proposed with the consideration of molecular interactions between the fluid and solid-surface. Firstly, the original and surface-energy modified Gibbs-Thomson equations were analyzed to calculate the melting points of mono noble metals and compared with the literature data, highlighting the importance of developing new models with the consideration of the interfacial effect. An empirical model was proposed to represent the interfacial effect for calculating the melting points of mono noble metals. Then, the mono noble metal nanoparticle supported at the flat solid-surface was chosen as the “model” system to develop a generalized model, and the developed model was extended to the supported alloy systems. The CO2 absorption capacity (or solubility) of the ionic liquids immobilized on the porous solid materials (substrates) was further investigated with the developed model. The main results were summarized as follows:To develop models for representing the melting points of mono noble metal nanoparticles, the original and surface-energy modified Gibbs-Thomson equations were analyzed and then further modified empirically considering the effect of substrate. The results revealed that the original Gibbs–Thomson equation is invalid for the particles with radii smaller than 10 nm, and the performance of the surface-energy modified equation was improved but further modification by considering the interfacial effect is necessary for the particles smller than 5 nm in radius. The empirical model with the interfacial effect further improved the model performance, and the adjustable parameters can be predicted quantitatively from the thermodynamic properties of the metal and substrate. Additionally, the micro-wetting parameter αw can be used to qualitatively study the overall impact of the substrate on the melting point depression.Combined with the analysis of the corresponding state theory, a generalized molecular thermodynamic model was developed. It was found that, the developed generalized model can provide accurate results of melting points with deviations within ± 15 K. The developed model was used to predict the melting point of Pt nanoparticles on the substrates of TiO2 and carbon (C), and the results showed that Pt on TiO2 was more stable than that on C, being consistent with the newly measured experimental results.The generalized model was further parameterized based on the analysis of the interfacial tensions and molar volumes of Al-Si3N4, Pb-Si, Bi-C, and In-C, and the model showed the deviation was within ± 36 K. The model with fully generalized parameters was extended to the supported alloy nanoparticles to illustrate their stabilities, where the common catalysts, Pd-Au alloy nanoparticles supported on different substrates, developed for H2O2 reaction, were chosen as the examples. The model prediction displayed that the Pd-Au alloy nanoparticles supported on C/TiO2 (molar ratio: 0.01) with the mass proportion Pd5Au1 (i.e., mass ratio of 5:1) is more stable than the mono noble metals. Furthermore, the model prediction indicated that the supported alloy nanoparticles are more stable than the supported Pd.The generalized model was also successfully extended to study the CO2 absorption capacity in the immobilized ionic liquids, where the Gibbs free energy of CO2 in the immobilized ionic liquids was modeled from both macro- and micro-analyses. The theoretical investigations revealed that the substrate has a crucial effect on the gas solubility in the ionic liquid immobilized on the substrates, and the performance of the model with the consideration of surface-energy and interfacial effects was further verified with the newly determined experimental data.
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| 15. |
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| 16. |
- Zhang, Zhibo, et al.
(author)
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Encapsulation of multiple enzymes in a metal–organic framework with enhanced electro-enzymatic reduction of CO2 to methanol
- 2021
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In: Green Chemistry. - : Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 23:6, s. 2362-2371
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Journal article (peer-reviewed)abstract
- Efficient enzymatic conversion of CO2 to methanol is limited by low CO2 solubility in water (33 mM), and the high-cost of the cofactor (NADH) hinders the potential large-scale application of CO2 enzymatic conversion. In this study, a bioelectrocatalytic system was established for tackling both these issues, and in this system enzymes were embedded in the metal–organic framework ZIF-8 via in situ encapsulation to increase the substrate (CO2) concentration and pre-concentrate NADH, and a Rh complex-grafted electrode was developed for regenerating NADH in a sustainable manner. The results showed that after encapsulation of enzymes in ZIF-8, the methanol concentration increased from 0.061 to 0.320 mM (5 fold) in three hours. Furthermore, after coupling with electrocatalytic NADH regeneration, the methanol concentration further increased to 0.742 mM (12 fold) compared to a free enzyme system. Overall, methanol was produced at a rate of 822 μmol g−1 h−1.
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| 17. |
- Ali, Asad, et al.
(author)
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Emerging strategies and developments in oxygen reduction reaction using high-performance platinum-based electrocatalysts
- 2024
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In: Nano Reseach. - : Tsinghua University Press. - 1998-0124 .- 1998-0000. ; 17:5, s. 3516-3532
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Research review (peer-reviewed)abstract
- The global practical implementation of proton exchange membrane fuel cells (PEMFCs) heavily relies on the advancement of highly effective platinum (Pt)-based electrocatalysts for the oxygen reduction reaction (ORR). To achieve high ORR performance, electrocatalysts with highly accessible reactive surfaces are needed to promote the uncovering of active positions for easy mass transportation. In this critical review, we introduce different approaches for the emerging development of effective ORR electrocatalysts, which offer high activity and durability. The strategies, including morphological engineering, geometric configuration modification via supporting materials, alloys regulation, core-shell, and confinement engineering of single atom electrocatalysts (SAEs), are discussed in line with the goals and requirements of ORR performance enhancement. We review the ongoing development of Pt electrocatalysts based on the syntheses, nanoarchitecture, electrochemical performances, and stability. We eventually explore the obstacles and research directions on further developing more effective electrocatalysts.
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| 18. |
- Ali, Asad, et al.
(author)
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Gram-scale production of in-situ generated iron carbide nanoparticles encapsulated via nitrogen and phosphorous co-doped bamboo-like carbon nanotubes for oxygen evolution reaction
- 2023
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In: Materials Science for Energy Technologies. - : Elsevier. - 2589-2991. ; 6, s. 301-309
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Journal article (peer-reviewed)abstract
- Optimizing electrocatalytic activity and recognizing the most reactive sites for oxygen evolution reaction (OER) electrocatalysts are valuable to the order of renewable power. In this research article, we explored an innovative in-situ annealing technique for constructing iron carbide nanoparticles (Fe3C NPs) encapsulated via nitrogen and phosphorous doped bamboo-shape carbon nanotubes (NP-CNTs) for OER. Interestingly, the constructed Fe3C NPs@NP-CNT-800 composite exhibited remarkable electrochemical operation and offered a stable current density of 10 mA/cm2 at a lower overpotential (280 mV) in an alkaline solution. Furthermore, an innovative Fe3C NPs@N,P-CNT-800 hybrid surpassed the standard RuO2 electrocatalyst in terms of OER performance and showed negligible degradation in chronoamperometric (21 h) and chronopotentiometry (3000 cycles) analyses. The remarkable performance and stability are ascribed to the Fe3C NPs, novel tubular bamboo-like morphology of its carbon materials, and heteroatom doping, which contribute to the electrochemical interfaces, large surface area, active catalytic sites, and rapid charge transfer kinetics.
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| 19. |
- An, Rong, et al.
(author)
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Atomic force microscopy probing interactions and microstructures of ionic liquids at solid surfaces
- 2022
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In: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; :14, s. 11098-11128
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Research review (peer-reviewed)abstract
- Ionic liquids (ILs) are room temperature molten salts that possess preeminent physicochemical properties and have shown great potential in many applications. However, the use of ILs in surface-dependent processes, e.g. energy storage, is hindered by the lack of a systematic understanding of the IL interfacial microstructure. ILs on the solid surface display rich ordering, arising from coulombic, van der Waals, solvophobic interactions, etc., all giving near-surface ILs distinct microstructures. Therefore, it is highly important to clarify the interactions of ILs with solid surfaces at the nanoscale to understand the microstructure and mechanism, providing quantitative structure–property relationships. Atomic force microscopy (AFM) opens a surface-sensitive way to probe the interaction force of ILs with solid surfaces in the layers from sub-nanometers to micrometers. Herein, this review showcases the recent progress of AFM in probing interactions and microstructures of ILs at solid interfaces, and the influence of IL characteristics, surface properties and external stimuli is thereafter discussed. Finally, a summary and perspectives are established, in which, the necessities of the quantification of IL–solid interactions at the molecular level, the development of in situ techniques closely coupled with AFM for probing IL–solid interfaces, and the combination of experiments and simulations are argued.
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| 20. |
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| 21. |
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| 22. |
- An, Rong, et al.
(author)
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Ti–Si–Zr–Zn Nanometallic Glass Substrate with a Tunable Zinc Composition for Surface-Enhanced Raman Scattering of Cytochrome c
- 2023
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In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 15:21, s. 25275-25284
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Journal article (peer-reviewed)abstract
- As a remarkably powerful analytical technique, surface-enhanced Raman scattering (SERS) continues to find applications from molecular biology and chemistry to environmental and food sciences. In search of reliable and affordable SERS substrates, the development has moved from noble metals to other diverse types of structures, e.g., nano-engineered semiconductor materials, but the cost of the enhancement factors (EF) substantially decreasing. In this work, we employ biocompatible thin films of Ti–Si–Zr–Zn nanometallic glasses as the SERS substrates, while tuning the Zn composition. Aided by quartz crystal microbalance, we find that the composition of 4.3% Zn (Ti–Si–Zr–Zn4.3) gives an ultrasensitive detection of Cytochrome c (Cyt c) with an EF of 1.38 × 104, 10-fold higher than the previously reported EF in the semiconducting metal oxide nanomaterials, such as TiO2, and even comparable to the reported noble-metal-assisted semiconducting tungsten oxide hydrate. Ti–Si–Zr–Zn4.3 exhibits a stronger adhesion force toward Cyt c, which ensures the strong binding of Cyt c to the surface, facilitating the Cyt c adsorption onto the surface and thus enhancing the SERS signal. The high separation efficiency of photoinduced electrons and holes in Ti–Si–Zr–Zn4.3 is also acknowledged for promoting the SERS activity.
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| 23. |
- Bao, Ningzhong, et al.
(author)
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Thermodynamic modeling and experimental verification for ion-exchange synthesis of K2O·6TiO2 and TiO2 fibers from K2O·4TiO2
- 2002
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In: Fluid Phase Equilibria. - 0378-3812 .- 1879-0224. ; 193, s. 229-243
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Journal article (peer-reviewed)abstract
- A thermodynamic model was established to determine ion-exchange conditions for the synthesis of potassium hexatitanate (K2O·6TiO2) and titanium dioxide (TiO2) from potassium tetratitanate (K2O·4TiO2) fiber. In the proposed model equilibrium species in the solid phase and corresponding ion-exchange equilibrium constants at 298.15 K were determined from the experimental data of Sasaki et al. [Inorg. Chem. 24 (1985) 2265]. In order to verify the proposed model, prediction results were compared with experimental data determined in literature and those measured in this work. The comparison shows a good agreement. Based on this, the proposed model was also used to predict more extensive suitable conditions for the synthesis of K2O·6TiO2 and TiO2.
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| 24. |
- Bülow, M., et al.
(author)
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Incorporating a concentration-dependent dielectric constant into ePC-SAFT. An application to binary mixtures containing ionic liquids
- 2019
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In: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 492, s. 26-33
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Journal article (peer-reviewed)abstract
- Primitive thermodynamic models for electrolyte solutions require the dielectric constant ε. This property strongly depends on the concentration of the electrolytes in the mixture. Neglecting this dependency might be reasonable for modeling solutions at low electrolyte concentrations. However, in solutions containing ionic liquids (ILs) and especially for the calculation of liquid-liquid equilibria (LLE) of systems with ILs, liquid phases often contain high IL concentrations. At such conditions, neglecting the influence of concentration on ε is an oversimplification. In this work, an approach to account for the concentration-dependent dielectric constant within the Debye-Hückel theory was implemented into electrolyte Perturbed-Chain Statistical Associating Fluid Theory (original ePC-SAFT). This new approach was then applied to model LLE of binary mixtures containing water and commonly used hydrophobic ILs. These common ILs are comprised of the IL-cations [C n mim] + , [C n py] + , [C n mpy] + , [C n mpyr] + , [C 4 m 4 py] + and the IL-anions [BF 4 ] - , [NTf 2 ] - , [PF 6 ] - , [TFO] - . The LLE of binary mixtures water + IL were modeled at ambient pressure and different temperatures with the new ePC-SAFT and with the original ePC-SAFT [Ji et al. DOI: 10.1016/j.fluid.2012.05.029] without the concentration-dependent ε. Overall, the new approach within ePC-SAFT shows superior modeling as well as correlation capability compared to original ePC-SAFT, which was concluded by comparing both models with LLE data from literature.
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| 25. |
- Cao, Jian, et al.
(author)
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Heterogeneous consecutive reaction kinetics of direct oxidation of H2 to H2O2: Effect and regulation of confined mass transfer
- 2023
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In: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 455
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Journal article (peer-reviewed)abstract
- Porous catalysts in heterogeneous reactions have played an important role in the modern chemical industry, but it is still challenging to quantitatively describe mass transfer and surface reaction behaviors of reactants in nano-confined space. Direct synthesis of hydrogen peroxide (H2O2) is considered as an attractive alternative to anthraquinone oxidation process, while the confined mass transfer of H2O2 in porous catalysts limits the reactivity. In this work, taking the consecutive reaction of H2O2 synthesis as an example, a quantitative method in modeling the effects of confined mass transfer on the reactivity was studied. More specifically, calorimetry was developed to characterize the confined structures of porous carbon experimentally, the linear nonequilibrium thermodynamics and the statistical mechanics method were further combined. Then, the heterogeneous consecutive reaction kinetics and the Thiele modulus influenced by confined mass transfer were modeled. Consequently, regulation strategies were proposed with the help of theoretical models. The optimized catalyst with biological skeleton carbon support and 0.5 wt% palladium loading shows an excellent catalytic performance. Lastly, for the mesoscience in heterogeneous reaction, the resistance was explored as a quantitative descriptor to compromise in the competition between mass transfer and surface reaction. The mesoscale structures were considered as the dynamic spatiotemporal distribution of substance concentrations, and the resistance minimization multi-scale (RMMS) model was proposed.
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