The solubility product constant(K_(sp))is an important concept in inorganic chemistry for determining the solubility of sparingly soluble ionic compounds in aqueous medium.K_(sp)guided precipitation reactions are a po...The solubility product constant(K_(sp))is an important concept in inorganic chemistry for determining the solubility of sparingly soluble ionic compounds in aqueous medium.K_(sp)guided precipitation reactions are a popular route towards the acquiring of inorganic solid materials or the removal of unwanted ions from an aqueous solution.Furthermore,the K_(sp)gap of two solids sharing the same cation or anion triggers precipitation transformation reactions if one solid is treated with an aqueous solution containing the different ion of the other solid with a significantly lower K_(sp)value.Herein,it is found that the K_(sp)values of the sulfides of transition metals in groups 9-12 of the periodic table of elements are significantly lower than the corresponding hydroxides,and this finding is taken advantage of for the preparation of transition metal sulfides through the precipitation transformation from the corresponding hydroxides in the aqueous solution of sodium sulfide.As an example,Cu(OH)_(2)nanowires are converted to nanostructured CuS with inherited morphology to a certain extent,which is applied for the electrochemical storage of alkali metal ions(Li^(+),Na^(+),K^(+));among them sodium ion batteries exhibits the most promising performances.The chemical equations from the hydroxides to sulfides are determined and the corresponding equilibrium constants are derived from the K_(sp)of the solids of hydroxides and sulfides without or with the hydrolysis equilibrium constants of the S_(2)-ions.Accordingly,a new concept,the precipitation transformation constant(K_(pt)),which means the equilibrium constant for precipitation transformation reactions,is proposed.展开更多
An orthogonal test was used to optimize the reaction conditions of roasting zinc oxide ore using（NH_4）_2SO_4. The optimized reaction conditions are defined as an（NH_4）_2SO_4/zinc molar ratio of 1.4：1, a roasting ...An orthogonal test was used to optimize the reaction conditions of roasting zinc oxide ore using（NH_4）_2SO_4. The optimized reaction conditions are defined as an（NH_4）_2SO_4/zinc molar ratio of 1.4：1, a roasting temperature of 440°C, and a thermostatic time of 60 min. The molar ratio of（NH_4）_2SO_4/zinc is the most predominant factor and the roasting temperature is the second significant factor that governs the zinc extraction. Thermogravimetric-differential thermal analysis was used for（NH_4）_2SO_4 and zinc mixed in a molar ratio of 1.4：1 at the heating rates of 5, 10, 15, and 20 K·min-1. Two strong endothermic peaks indicate that the complex chemical reactions occur at approximately 290°C and 400°C. XRD analysis was employed to examine the transformations of mineral phases during roasting process. Kinetic parameters, including reaction apparent activation energy, reaction order, and frequency factor, were calculated by the Doyle-Ozawa and Kissinger methods. Corresponding to the two endothermic peaks, the kinetic equations were obtained.展开更多
A facile synthesis for cyanochlorin related to chlorophyll from a formyl-substituted chlorin, by the oxidation of methyl （pyro）pheophorbide-a, was accomplished. These readily available chlorin aldehydes were assembl...A facile synthesis for cyanochlorin related to chlorophyll from a formyl-substituted chlorin, by the oxidation of methyl （pyro）pheophorbide-a, was accomplished. These readily available chlorin aldehydes were assembled together with hydroxylamine hydrochloride in a tandem process to produce the corresponding chlorin nitriles in moderate to good yields. The formation of chlorin nitrile was discussed and a possible mechanism for the corresponding cyanation reaction was tentatively proposed.展开更多
Electrochemical nitrogen transformation techniques represent a burgeoning avenue for nitrogen pollutant remediation and synthesizing valuable nitrogenous products from atmospheric nitrogen.Intermetallic compounds(IMCs...Electrochemical nitrogen transformation techniques represent a burgeoning avenue for nitrogen pollutant remediation and synthesizing valuable nitrogenous products from atmospheric nitrogen.Intermetallic compounds(IMCs)nanocrystals,featured with unique geometric,electronic and functional properties,have emerged as promising candidates.The review discusses various synthesis approaches for IMCs,including thermal annealing,wet chemical synthesis,electrochemical synthesis,and other emerging methods,analyzing their advantages and limitations.Then we summarized the recent advances of IMCs in electrocatalytic nitrogen transformation reactions,such as nitrate reduction reaction,nitric oxide reduction reaction,nitrogen reduction reaction,and hydrazine oxidation reaction.Despite significant progress,challenges remain in the field,particularly in adopting more refined strategies to improve catalyst performance and stability.This review aims to comprehensively understand the structural properties of IMCs and their structure-performance relationship,guiding the development of more efficient and stable catalysts for future nitrogen electrochemistry.展开更多
The reduction of high-chromium vanadium–titanium magnetite as a typical titanomagnetite containing 0.95wt% V2O5 and 0.61wt% Cr2O3 by H2–CO–CO2 gas mixtures was investigated from 1223 to 1373 K. Both the reduction d...The reduction of high-chromium vanadium–titanium magnetite as a typical titanomagnetite containing 0.95wt% V2O5 and 0.61wt% Cr2O3 by H2–CO–CO2 gas mixtures was investigated from 1223 to 1373 K. Both the reduction degree and reduction rate increase with increasing temperature and increasing hydrogen content. At a temperature of 1373 K, an H2/CO ratio of 5/2 by volume, and a reduction time of 40 min, the degree of reduction reaches 95%. The phase transformation during reduction is hypothesized to proceed as follows： Fe2O3 → Fe3O4 → FeO → Fe; Fe9 TiO 15 ＋ Fe2Ti3O9 → Fe2.75Ti0.25O4 → FeT iO 3 → TiO 2;（Cr0.15V0.85）2O3 → Fe2VO4; and Cr1.3Fe0.7O3 → FeC r2O4. The reduction is controlled by the mixed internal diffusion and interfacial reaction at the initial stage; however, the interfacial reaction is dominant. As the reduction proceeds, the internal diffusion becomes the controlling step.展开更多
The nitrogen cycle is one of the most important biogeochemical cycles on Earth.This cycle mainly involves redox conversion of dinitrogen when it is converted into ammonia(nitrogen fixation pathway)and the cycle is com...The nitrogen cycle is one of the most important biogeochemical cycles on Earth.This cycle mainly involves redox conversion of dinitrogen when it is converted into ammonia(nitrogen fixation pathway)and the cycle is completed with the conversion of ammonia to dinitrogen(involving nitrification and denitrification pathways).The application of Ru(edta)complexes(edta^(4-)=ethylenediaminetetraacetate)in nitrogen cycle-related electrochemical transformation reactions has not been systematically reviewed to date.This review aims to report the research progression on the use of Ru(edta)complexes in catalyzing N-cycle electrochemical transformations.In this review,the role of Ru(edta)complexes in mediating electrochemical reactions pertaining to nitrogen fixation and denitrification in the nitrogen cycle has been discussed,providing in-depth mechanistic knowledge for understanding the varied roles of Ru(edta)complexes pertaining to the many N-cycle-related electrochemical transformations.展开更多
基金supported by the National Natural Science Foundation of China(21905099,52004179)Innovative Research Team of Shanxi Hundred Talents Program(DC2000005702)Shanxi“1331 Project”(DT17100004).
文摘The solubility product constant(K_(sp))is an important concept in inorganic chemistry for determining the solubility of sparingly soluble ionic compounds in aqueous medium.K_(sp)guided precipitation reactions are a popular route towards the acquiring of inorganic solid materials or the removal of unwanted ions from an aqueous solution.Furthermore,the K_(sp)gap of two solids sharing the same cation or anion triggers precipitation transformation reactions if one solid is treated with an aqueous solution containing the different ion of the other solid with a significantly lower K_(sp)value.Herein,it is found that the K_(sp)values of the sulfides of transition metals in groups 9-12 of the periodic table of elements are significantly lower than the corresponding hydroxides,and this finding is taken advantage of for the preparation of transition metal sulfides through the precipitation transformation from the corresponding hydroxides in the aqueous solution of sodium sulfide.As an example,Cu(OH)_(2)nanowires are converted to nanostructured CuS with inherited morphology to a certain extent,which is applied for the electrochemical storage of alkali metal ions(Li^(+),Na^(+),K^(+));among them sodium ion batteries exhibits the most promising performances.The chemical equations from the hydroxides to sulfides are determined and the corresponding equilibrium constants are derived from the K_(sp)of the solids of hydroxides and sulfides without or with the hydrolysis equilibrium constants of the S_(2)-ions.Accordingly,a new concept,the precipitation transformation constant(K_(pt)),which means the equilibrium constant for precipitation transformation reactions,is proposed.
基金financially supported by the National Natural Science Foundation of China(Nos.51204054 and 51574084)the Fundamental Research Funds for the Central Universities of China(No.N150204009)the National Basic Research Priorities Program of China(No.2014CB643405)
文摘An orthogonal test was used to optimize the reaction conditions of roasting zinc oxide ore using（NH_4）_2SO_4. The optimized reaction conditions are defined as an（NH_4）_2SO_4/zinc molar ratio of 1.4：1, a roasting temperature of 440°C, and a thermostatic time of 60 min. The molar ratio of（NH_4）_2SO_4/zinc is the most predominant factor and the roasting temperature is the second significant factor that governs the zinc extraction. Thermogravimetric-differential thermal analysis was used for（NH_4）_2SO_4 and zinc mixed in a molar ratio of 1.4：1 at the heating rates of 5, 10, 15, and 20 K·min-1. Two strong endothermic peaks indicate that the complex chemical reactions occur at approximately 290°C and 400°C. XRD analysis was employed to examine the transformations of mineral phases during roasting process. Kinetic parameters, including reaction apparent activation energy, reaction order, and frequency factor, were calculated by the Doyle-Ozawa and Kissinger methods. Corresponding to the two endothermic peaks, the kinetic equations were obtained.
基金supported by research grants from the National Natural Science Foundation of China (No. 21272048)Natural Science Foundation of Shandong Province (No. ZR2015BQ012)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (to J. Li)
文摘A facile synthesis for cyanochlorin related to chlorophyll from a formyl-substituted chlorin, by the oxidation of methyl （pyro）pheophorbide-a, was accomplished. These readily available chlorin aldehydes were assembled together with hydroxylamine hydrochloride in a tandem process to produce the corresponding chlorin nitriles in moderate to good yields. The formation of chlorin nitrile was discussed and a possible mechanism for the corresponding cyanation reaction was tentatively proposed.
基金funded by the National Natural Science Foundation of China(No.22405173)the Shanghai Pujiang Program(No.23PJ1409100)the Project of Overseas Leading Talent of Shanghai.
文摘Electrochemical nitrogen transformation techniques represent a burgeoning avenue for nitrogen pollutant remediation and synthesizing valuable nitrogenous products from atmospheric nitrogen.Intermetallic compounds(IMCs)nanocrystals,featured with unique geometric,electronic and functional properties,have emerged as promising candidates.The review discusses various synthesis approaches for IMCs,including thermal annealing,wet chemical synthesis,electrochemical synthesis,and other emerging methods,analyzing their advantages and limitations.Then we summarized the recent advances of IMCs in electrocatalytic nitrogen transformation reactions,such as nitrate reduction reaction,nitric oxide reduction reaction,nitrogen reduction reaction,and hydrazine oxidation reaction.Despite significant progress,challenges remain in the field,particularly in adopting more refined strategies to improve catalyst performance and stability.This review aims to comprehensively understand the structural properties of IMCs and their structure-performance relationship,guiding the development of more efficient and stable catalysts for future nitrogen electrochemistry.
基金financially supported by the National Natural Science Foundation of China (No. 51090384)the National High-Tech Research and Development Program of China (No. 2012AA062302)the Fundamental Research Funds for the Central Universities of China (Nos. N110202001 and N130602003)
文摘The reduction of high-chromium vanadium–titanium magnetite as a typical titanomagnetite containing 0.95wt% V2O5 and 0.61wt% Cr2O3 by H2–CO–CO2 gas mixtures was investigated from 1223 to 1373 K. Both the reduction degree and reduction rate increase with increasing temperature and increasing hydrogen content. At a temperature of 1373 K, an H2/CO ratio of 5/2 by volume, and a reduction time of 40 min, the degree of reduction reaches 95%. The phase transformation during reduction is hypothesized to proceed as follows： Fe2O3 → Fe3O4 → FeO → Fe; Fe9 TiO 15 ＋ Fe2Ti3O9 → Fe2.75Ti0.25O4 → FeT iO 3 → TiO 2;（Cr0.15V0.85）2O3 → Fe2VO4; and Cr1.3Fe0.7O3 → FeC r2O4. The reduction is controlled by the mixed internal diffusion and interfacial reaction at the initial stage; however, the interfacial reaction is dominant. As the reduction proceeds, the internal diffusion becomes the controlling step.
文摘The nitrogen cycle is one of the most important biogeochemical cycles on Earth.This cycle mainly involves redox conversion of dinitrogen when it is converted into ammonia(nitrogen fixation pathway)and the cycle is completed with the conversion of ammonia to dinitrogen(involving nitrification and denitrification pathways).The application of Ru(edta)complexes(edta^(4-)=ethylenediaminetetraacetate)in nitrogen cycle-related electrochemical transformation reactions has not been systematically reviewed to date.This review aims to report the research progression on the use of Ru(edta)complexes in catalyzing N-cycle electrochemical transformations.In this review,the role of Ru(edta)complexes in mediating electrochemical reactions pertaining to nitrogen fixation and denitrification in the nitrogen cycle has been discussed,providing in-depth mechanistic knowledge for understanding the varied roles of Ru(edta)complexes pertaining to the many N-cycle-related electrochemical transformations.
