Fe(Ⅲ)has been proved to be a more eff ective oxidant than dissolved oxygen at ambient temperature,however,the role of Fe(Ⅲ)in pyrite acidic pressure oxidation was rarely discussed so far.In this paper,in-situ electr...Fe(Ⅲ)has been proved to be a more eff ective oxidant than dissolved oxygen at ambient temperature,however,the role of Fe(Ⅲ)in pyrite acidic pressure oxidation was rarely discussed so far.In this paper,in-situ electrochemical investigation was performed using a flow-through autoclave system in acidic pressure oxidation environment.The results illustrated that increasing Fe(Ⅲ)concentrations led to raising in redox potential of the solution,and decreased passivation of pyrite caused by deposition of elemental sulfur.Reduction of Fe(Ⅲ)at pyrite surface was a fast reaction with low activation energy,it was only slightly promoted by rising temperatures.While,the oxidation rate of pyrite at all investigated Fe(Ⅲ)concentrations increased obviously with rising temperatures,the anodic reaction was the rate-limiting step in the overall reaction.Activation energy of pyrite oxidation decreased from 47.74 to 28.79 kJ/mol when Fe(Ⅲ)concentration was increased from 0.05 to 0.50 g/L,showing that the reaction kinetics were limited by the rate of electrochemical reaction at low Fe(Ⅲ)concentrations,while,it gradually turned to be diffusion control with increasing Fe(Ⅲ)concentrations.展开更多
For the rational manipulation of the production quality of high-temperature metallurgical engineering,there are many challenges in understanding the processes involved because of the black box chemical/electrochemical...For the rational manipulation of the production quality of high-temperature metallurgical engineering,there are many challenges in understanding the processes involved because of the black box chemical/electrochemical reactors.To overcome this issue,various in-situ characterization methods have been recently developed to analyze the interactions between the composition,microstructure,and solid-liquid interface of high-temperature electrochemical electrodes and molten salts.In this review,recent progress of in-situ hightemperature characterization techniques is discussed to summarize the advances in understanding the processes in metallurgical engineering.In-situ high-temperature technologies and analytical methods mainly include synchrotron X-ray diffraction(s-XRD),laser scanning confocal microscopy,and X-ray computed microtomography(X-rayμ-CT),which are important platforms for analyzing the structure and morphology of the electrodes to reveal the complexity and variability of their interfaces.In addition,laser-induced breakdown spectroscopy,high-temperature Raman spectroscopy,and ultraviolet-visible absorption spectroscopy provide microscale characterizations of the composition and structure of molten salts.More importantly,the combination of X-rayμ-CT and s-XRD techniques enables the investigation of the chemical reaction mechanisms at the two-phase interface.Therefore,these in-situ methods are essential for analyzing the chemical/electrochemical kinetics of high-temperature reaction processes and establishing the theoretical principles for the efficient and stable operation of chemical/electrochemical metallurgical processes.展开更多
In-situ time-resolved Raman spectroscopy(TRRS)has been applied on studies of electrochemical adsorption of thiocyanate at silver electrode during potential cycles and potential step.It is shown that some dynamic infor...In-situ time-resolved Raman spectroscopy(TRRS)has been applied on studies of electrochemical adsorption of thiocyanate at silver electrode during potential cycles and potential step.It is shown that some dynamic information about the adsorption and desorption processes can be obtained.展开更多
The mixed-valence isopolyanion Mo6O193- was investigated by means of cyclic voltammographic, in-situ FTIR and UV-Visible-Near-IR spectro-electrochemicalmethods in aprotic media. The experimental results indicate that ...The mixed-valence isopolyanion Mo6O193- was investigated by means of cyclic voltammographic, in-situ FTIR and UV-Visible-Near-IR spectro-electrochemicalmethods in aprotic media. The experimental results indicate that the Mo6O193-was formed whereafter Mo6O193- was reduced, (E0' = - 0. 690 V, n = 1 ). The characteristic absorptions of Mo6O193- are 500 nm, 900 nm and 1100 nm in UV-VisibleNear-IR spectrum and 940 cm-1 in IR spectrum.展开更多
Ammonia is toxic, colorless, and harmful to human health. It is important to detect ammonia effectively by gas sensors. In this paper, the mechanism of ammonia sensing on polypyrroles (PPy) films at room temperature h...Ammonia is toxic, colorless, and harmful to human health. It is important to detect ammonia effectively by gas sensors. In this paper, the mechanism of ammonia sensing on polypyrroles (PPy) films at room temperature has been investigated using a real-time, in-situ Fourier-transform infrared (FT-IR) spectroscopy. The introduction of ammonia results in a structural transformation of PPy films, which is confirmed by FT-IR spectrums. The structure and morphology of the products after the reaction between ammonia and PPy were investigated in detail by FT-IR spectrum and scanning electron microscope (SEM). It was found that the morphology of PPy films was changed to some degree after the reaction. Our results demonstrate that FT-IR spectroscopy is an extremely suitable technique for the characterization of the specific reaction between PPy and ammonia, since it allows monitoring the reaction at room temperature in real time. After the reaction between PPy and ammonia, the concentration of the carrier increases, and the resistance of PPy films decreases, indicating the sensitivity of detection of ammonia.展开更多
Lithium(Li)metal anodes promise an ultrahigh theoretical energy density and low redox potential,thus being the critical energy material for next-generation batteries.Unfortunately,the formation of Li dendrites in Li m...Lithium(Li)metal anodes promise an ultrahigh theoretical energy density and low redox potential,thus being the critical energy material for next-generation batteries.Unfortunately,the formation of Li dendrites in Li metal anodes remarkably hinders the practical applications of Li metal anodes.Herein,the dynamic evolution of discrete Li dendrites and aggregated Li dendrites with increasing current densities is visualized by in-situ optical microscopy in conjunction with ex-situ scanning electron microscopy.As revealed by the phase field simulations,the formation of aggregated Li dendrites under high current density is attributed to the locally concentrated electric field rather than the depletion of Li ions.More specifically,the locally concentrated electric field stems from the spatial inhomogeneity on the Li metal surface and will be further enhanced with increasing current densities.Adjusting the above two factors with the help of the constructed phase field model is able to regulate the electrodeposited morphology from aggregated Li dendrites to discrete Li dendrites,and ultimately columnar Li morphology.The methodology and mechanistic understanding established herein give a significant step toward the practical applications of Li metal anodes.展开更多
Rechargeable lithium-carbon dioxide(Li-CO_(2))batteries have attracted much attention due to their high theoretical energy densities and capture of C0_(2).However,the electrochemical reaction mechanisms of rechargeabl...Rechargeable lithium-carbon dioxide(Li-CO_(2))batteries have attracted much attention due to their high theoretical energy densities and capture of C0_(2).However,the electrochemical reaction mechanisms of rechargeable Lo-CO_(2) batteries,particularly the decomposition mechanisms of the discharge product Li_(2)CO_(3) are still unclear,impeding their practical applications.Exploring electrochemistry of Li_(2)CO_(3) is critical for improving the performance of Li-C0_(2) batteries.Herein,in-situ environmental transmission electron microscopy(ETEM)technique was used to study electrochemistry of Li_(2)CO_(3) in Li-C0_(2) batteries during discharge and charge processes.During discharge,Li_(2)CO_(3) was nucleated and accumulated on the surface of the cathode media such as carbon nanotubes(CNTs)and Ag nanowires(Ag NWs),but it was hard to decompose during charging at room temperature.To promote the decomposition of Li2C03,the charge reactions were conducted at high temperatures,during which Li_(2)CO_(3) was decomposed to lithium with release of gases.Density functional theory(DFT)calculations revealed that the synergistic effect of temperature and biasing facilitates the decomposition of Li_(2)CO_(3).This study not only provides a fundamental understanding to the high temperature Li-C0_(2) nanobatteries,but also offers a valid technique,i.e.,discharging/charging at high temperatures,to improve the cyclability of Li-CO_(2) batteries for energy storage applications.展开更多
Core-shell nanostructures constituted by a plasmonic core and an ultrathin shell have drawn enormous attentions in enhanced spectroscopies,catalysis,energy,and other fields because of their splendid properties such as...Core-shell nanostructures constituted by a plasmonic core and an ultrathin shell have drawn enormous attentions in enhanced spectroscopies,catalysis,energy,and other fields because of their splendid properties such as multifunctionality,stability,and adjustability.In this article,we summarized the endeavors made by our group in the past decade about the core-shell nanostructures in the shell-isolated nanoparticle-enhanced Raman spectroscopy(SHINERS)and plasmon-enhanced spectroscopies.Meanwhile,the potential challenges and perspectives about core-shell nanostructures in spectroscopies have also been proposed.Thus,we believe this article would provide an avenue for a comprehensive understanding of enhanced spectroscopies with core-shell nanostructures.展开更多
A novel Co^Ⅱ-Fenton-like heterogeneous catalyst,(H3O)2[Co^Ⅱ(phen)(H2O)2]2[Mo^Ⅵ5O15(PO4)2]·4H2O (phen=1,10-phenanthroline,C12N2H8)(1),is synthesized and utilized for photocatalytic degradation of organic dyes a...A novel Co^Ⅱ-Fenton-like heterogeneous catalyst,(H3O)2[Co^Ⅱ(phen)(H2O)2]2[Mo^Ⅵ5O15(PO4)2]·4H2O (phen=1,10-phenanthroline,C12N2H8)(1),is synthesized and utilized for photocatalytic degradation of organic dyes and antibiotic in a wide range of pH.The experimental results show that 1 acting as the Fenton-like catalyst with H2O2 exhibits remarkable activity at pH 3–9 under vis-light irradiation and is merited with excellent recyclability and reusability.A variety of analytical methods,including in-situ electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT) calculations,are applied to study the mechanism on generation of·OH and O2^·-radicals for photocatalytic degradation.It suggests that,unlike the classical Fenton process involving the redox transformation of the central cations,the generation of·OH and O2^·-radicals is associated with the substitution of the coordinating water molecules at Co(Ⅱ) by H2O2 and/or OOH^-,followed by the light-driven O–O bond cleavage and dissociation.The outcomes of this study are striking which overcome the obstacles in the classical Fe^Ⅱ-Fenton process,including the slow redox transformation between Fe(Ⅱ) and Fe(Ⅲ) and the production of massive iron precipitates especially at elevated pH.It opens up new avenues for the development of the high-performance Fenton(-like) catalysts for photocatalytic degradation over extended pH and provides new insight into the related process.展开更多
基金supported by the Science and Technology Foundation of Guizhou Province,China(No.[2020]1Y163)the National Natural Science Foundation of China(No.41827802).
文摘Fe(Ⅲ)has been proved to be a more eff ective oxidant than dissolved oxygen at ambient temperature,however,the role of Fe(Ⅲ)in pyrite acidic pressure oxidation was rarely discussed so far.In this paper,in-situ electrochemical investigation was performed using a flow-through autoclave system in acidic pressure oxidation environment.The results illustrated that increasing Fe(Ⅲ)concentrations led to raising in redox potential of the solution,and decreased passivation of pyrite caused by deposition of elemental sulfur.Reduction of Fe(Ⅲ)at pyrite surface was a fast reaction with low activation energy,it was only slightly promoted by rising temperatures.While,the oxidation rate of pyrite at all investigated Fe(Ⅲ)concentrations increased obviously with rising temperatures,the anodic reaction was the rate-limiting step in the overall reaction.Activation energy of pyrite oxidation decreased from 47.74 to 28.79 kJ/mol when Fe(Ⅲ)concentration was increased from 0.05 to 0.50 g/L,showing that the reaction kinetics were limited by the rate of electrochemical reaction at low Fe(Ⅲ)concentrations,while,it gradually turned to be diffusion control with increasing Fe(Ⅲ)concentrations.
基金financially supported by the National Key R&D Program of China(No.2022YFC2906100).
文摘For the rational manipulation of the production quality of high-temperature metallurgical engineering,there are many challenges in understanding the processes involved because of the black box chemical/electrochemical reactors.To overcome this issue,various in-situ characterization methods have been recently developed to analyze the interactions between the composition,microstructure,and solid-liquid interface of high-temperature electrochemical electrodes and molten salts.In this review,recent progress of in-situ hightemperature characterization techniques is discussed to summarize the advances in understanding the processes in metallurgical engineering.In-situ high-temperature technologies and analytical methods mainly include synchrotron X-ray diffraction(s-XRD),laser scanning confocal microscopy,and X-ray computed microtomography(X-rayμ-CT),which are important platforms for analyzing the structure and morphology of the electrodes to reveal the complexity and variability of their interfaces.In addition,laser-induced breakdown spectroscopy,high-temperature Raman spectroscopy,and ultraviolet-visible absorption spectroscopy provide microscale characterizations of the composition and structure of molten salts.More importantly,the combination of X-rayμ-CT and s-XRD techniques enables the investigation of the chemical reaction mechanisms at the two-phase interface.Therefore,these in-situ methods are essential for analyzing the chemical/electrochemical kinetics of high-temperature reaction processes and establishing the theoretical principles for the efficient and stable operation of chemical/electrochemical metallurgical processes.
文摘In-situ time-resolved Raman spectroscopy(TRRS)has been applied on studies of electrochemical adsorption of thiocyanate at silver electrode during potential cycles and potential step.It is shown that some dynamic information about the adsorption and desorption processes can be obtained.
文摘The mixed-valence isopolyanion Mo6O193- was investigated by means of cyclic voltammographic, in-situ FTIR and UV-Visible-Near-IR spectro-electrochemicalmethods in aprotic media. The experimental results indicate that the Mo6O193-was formed whereafter Mo6O193- was reduced, (E0' = - 0. 690 V, n = 1 ). The characteristic absorptions of Mo6O193- are 500 nm, 900 nm and 1100 nm in UV-VisibleNear-IR spectrum and 940 cm-1 in IR spectrum.
文摘Ammonia is toxic, colorless, and harmful to human health. It is important to detect ammonia effectively by gas sensors. In this paper, the mechanism of ammonia sensing on polypyrroles (PPy) films at room temperature has been investigated using a real-time, in-situ Fourier-transform infrared (FT-IR) spectroscopy. The introduction of ammonia results in a structural transformation of PPy films, which is confirmed by FT-IR spectrums. The structure and morphology of the products after the reaction between ammonia and PPy were investigated in detail by FT-IR spectrum and scanning electron microscope (SEM). It was found that the morphology of PPy films was changed to some degree after the reaction. Our results demonstrate that FT-IR spectroscopy is an extremely suitable technique for the characterization of the specific reaction between PPy and ammonia, since it allows monitoring the reaction at room temperature in real time. After the reaction between PPy and ammonia, the concentration of the carrier increases, and the resistance of PPy films decreases, indicating the sensitivity of detection of ammonia.
基金supported by the National Natural Science Foundation of China(22061132002,U1801257,and 21825501)Russell Sage Foundation project(21-43-00006)+2 种基金the National Key Research and Development Program(2016YFA0200102 and 2016YFA0202500)Beijing Municipal Natural Science Foundation(Z20J00043)the Tsinghua University Initiative Scientific Research Program。
文摘Lithium(Li)metal anodes promise an ultrahigh theoretical energy density and low redox potential,thus being the critical energy material for next-generation batteries.Unfortunately,the formation of Li dendrites in Li metal anodes remarkably hinders the practical applications of Li metal anodes.Herein,the dynamic evolution of discrete Li dendrites and aggregated Li dendrites with increasing current densities is visualized by in-situ optical microscopy in conjunction with ex-situ scanning electron microscopy.As revealed by the phase field simulations,the formation of aggregated Li dendrites under high current density is attributed to the locally concentrated electric field rather than the depletion of Li ions.More specifically,the locally concentrated electric field stems from the spatial inhomogeneity on the Li metal surface and will be further enhanced with increasing current densities.Adjusting the above two factors with the help of the constructed phase field model is able to regulate the electrodeposited morphology from aggregated Li dendrites to discrete Li dendrites,and ultimately columnar Li morphology.The methodology and mechanistic understanding established herein give a significant step toward the practical applications of Li metal anodes.
基金supported by the the National Natural Science Foundation of China(Nos.52022088,51971245,51772262,21406191,U20A20336,and 21935009)Beijing Natural Science Foundation(No.2202046)+3 种基金Selective funding for provincial postdoctoral research projects(No.B2019003018)Fok Ying-Tong Education Foundation of China(No.171064)Natural Science Foundation of Hebei Province(Nos.B2020203037,and B2018203297)Hunan Innovation Team(No.2018RS3091).
文摘Rechargeable lithium-carbon dioxide(Li-CO_(2))batteries have attracted much attention due to their high theoretical energy densities and capture of C0_(2).However,the electrochemical reaction mechanisms of rechargeable Lo-CO_(2) batteries,particularly the decomposition mechanisms of the discharge product Li_(2)CO_(3) are still unclear,impeding their practical applications.Exploring electrochemistry of Li_(2)CO_(3) is critical for improving the performance of Li-C0_(2) batteries.Herein,in-situ environmental transmission electron microscopy(ETEM)technique was used to study electrochemistry of Li_(2)CO_(3) in Li-C0_(2) batteries during discharge and charge processes.During discharge,Li_(2)CO_(3) was nucleated and accumulated on the surface of the cathode media such as carbon nanotubes(CNTs)and Ag nanowires(Ag NWs),but it was hard to decompose during charging at room temperature.To promote the decomposition of Li2C03,the charge reactions were conducted at high temperatures,during which Li_(2)CO_(3) was decomposed to lithium with release of gases.Density functional theory(DFT)calculations revealed that the synergistic effect of temperature and biasing facilitates the decomposition of Li_(2)CO_(3).This study not only provides a fundamental understanding to the high temperature Li-C0_(2) nanobatteries,but also offers a valid technique,i.e.,discharging/charging at high temperatures,to improve the cyclability of Li-CO_(2) batteries for energy storage applications.
基金the National Key Research and Development Program of China(Nos.2020YFB1505800 and 2019YFA0705400)the National Natural Science Foundation of China(NSFC)(Nos.21925404,22002128,21972117,and 21902137)+1 种基金the Fundamental Research Funds for the Central Universities(No.20720210069)the Science and Technology Planning Project of Fujian Province(No.2019Y4001).
文摘Core-shell nanostructures constituted by a plasmonic core and an ultrathin shell have drawn enormous attentions in enhanced spectroscopies,catalysis,energy,and other fields because of their splendid properties such as multifunctionality,stability,and adjustability.In this article,we summarized the endeavors made by our group in the past decade about the core-shell nanostructures in the shell-isolated nanoparticle-enhanced Raman spectroscopy(SHINERS)and plasmon-enhanced spectroscopies.Meanwhile,the potential challenges and perspectives about core-shell nanostructures in spectroscopies have also been proposed.Thus,we believe this article would provide an avenue for a comprehensive understanding of enhanced spectroscopies with core-shell nanostructures.
基金This work was supported by the National Natural Science Foundation of China(21872105,22072107,21802142)the Natural Science Foundation of Fujian Province(2020J01367)+2 种基金the Natural Science Foundation of Longyan City(2018LYF8010)the Science&Technology Commission of Shanghai Municipality(19DZ2271500)We are indebted to Prof.Xuxu Wang(Fuzhou University)for valuable comments and suggestions.
文摘A novel Co^Ⅱ-Fenton-like heterogeneous catalyst,(H3O)2[Co^Ⅱ(phen)(H2O)2]2[Mo^Ⅵ5O15(PO4)2]·4H2O (phen=1,10-phenanthroline,C12N2H8)(1),is synthesized and utilized for photocatalytic degradation of organic dyes and antibiotic in a wide range of pH.The experimental results show that 1 acting as the Fenton-like catalyst with H2O2 exhibits remarkable activity at pH 3–9 under vis-light irradiation and is merited with excellent recyclability and reusability.A variety of analytical methods,including in-situ electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT) calculations,are applied to study the mechanism on generation of·OH and O2^·-radicals for photocatalytic degradation.It suggests that,unlike the classical Fenton process involving the redox transformation of the central cations,the generation of·OH and O2^·-radicals is associated with the substitution of the coordinating water molecules at Co(Ⅱ) by H2O2 and/or OOH^-,followed by the light-driven O–O bond cleavage and dissociation.The outcomes of this study are striking which overcome the obstacles in the classical Fe^Ⅱ-Fenton process,including the slow redox transformation between Fe(Ⅱ) and Fe(Ⅲ) and the production of massive iron precipitates especially at elevated pH.It opens up new avenues for the development of the high-performance Fenton(-like) catalysts for photocatalytic degradation over extended pH and provides new insight into the related process.
