Et4N)2pd(i-mnt)2.fw = 647. 04, monoclinic,space group P21/c;a =9.511(1), b = 11.612(2), c=14.820(3)A,g= 94.38(1)',I'= 1631.9(5)A;7=2' D.=1.32g.cnl-;F (000)=672, R=0 0324, R. = 0'0298.Tills is a new e,\...Et4N)2pd(i-mnt)2.fw = 647. 04, monoclinic,space group P21/c;a =9.511(1), b = 11.612(2), c=14.820(3)A,g= 94.38(1)',I'= 1631.9(5)A;7=2' D.=1.32g.cnl-;F (000)=672, R=0 0324, R. = 0'0298.Tills is a new e,\alil[)le ot' X-raycharacterized Pd colllplexes with bivalent anion l,1 -dithiolato ligands an(i IIis reactioll witll(Et'N)zWS# gives (Et4N)ZWS4Pd(i-1lint).展开更多
The prototypical E2 elimination and SN2 sub-stitution reactions between microsolvated fluoride and ethyl bromide show unexpected dynamic behaviors in mechanistic evolution driven by solvation and collision activation....The prototypical E2 elimination and SN2 sub-stitution reactions between microsolvated fluoride and ethyl bromide show unexpected dynamic behaviors in mechanistic evolution driven by solvation and collision activation.Considering the steric effects,the gas-phase selectivity favors an E2 pathway barely dependent on collision energies.Remarkably,base solvation steers the reaction in an effective way toward substitution at a near-thermal energy,whereas the governing high-energy events retain elimination.Chemical dynamics simulations reproduce exper-imental findings and uncover a crucial solute-solvent coupling in determining such competing processes.Interestingly,collision activation can tune the underlying atomistic dynamics essentially in the reactant entrance channel and cause a mechanism shift.These features for the ubiquitous competing E2/SN2 dynamics remain quite unknown,providing unique insight into reaction selectivity for complex chemical networks.展开更多
Ultrathin small MoS2nanosheets exhibit a higher electrocatalytic activity for the hydrogen evolution reaction.However,strong interactions between MoS2layers may result in aggregation;together with the low conductivity...Ultrathin small MoS2nanosheets exhibit a higher electrocatalytic activity for the hydrogen evolution reaction.However,strong interactions between MoS2layers may result in aggregation;together with the low conductivity of MoS2,this may lower its electrocatalytic activity.In this paper we present a method that we developed to directly produce solid S,N co‐doped carbon(SNC)with a graphite structure and multiple surface groups through a hydrothermal route.When Na2MoO4was added to the reaction,polymolybdate could be anchored into the carbon materials via a chemical interaction that helps polymolybdate disperse uniformly into the SNC.After a high temperature treatment,polymolybdate transformed into MoS2at800°C for6h in a N2atmosphere at a heating rate of5°C/min,owing to S2?being released from the SNC during the treatment(denoted as MoS2/SNC‐800‐6h).The SNC effectively prevents MoS2from aggregating into large particles,and we successfully prepared highly dispersed MoS2in the SNC matrix.Electrochemical characterizations indicate that MoS2/SNC‐900‐12h exhibits a low onset potential of115mV and a low overpotential of237mV at a current density of10mA/cm2.Furthermore,MoS2/SNC‐900‐12h also had an excellent stability with only^2.6%decay at a current density of10mA/cm2after5000test cycles.展开更多
Biochar,as a potential CO_(2) adsorbent,is of great significance in addressing the problem of global warming.Previous studies have demonstrated that the CO_(2) adsorption performance of biochar can be improved by nitr...Biochar,as a potential CO_(2) adsorbent,is of great significance in addressing the problem of global warming.Previous studies have demonstrated that the CO_(2) adsorption performance of biochar can be improved by nitrogen and sulfur doping.Co-doping can integrate the structure and function of two elements.However,the physicochemical interaction of nitrogen and sulfur during doping and the CO_(2) adsorption process remains unclear in co-doped biochar.In this study,the heteroatom-doped biochar was prepared with different additives(urea,sodium thiosulfate,and thiourea)via hydrothermal carbonization,and the physicochemical interaction of nitrogen and sulfur in co-doped biochar was investigated extensively.The findings revealed that nitrogen and sulfur competed for limited doped active sites on the carbon skeleton during the co-doping process.Interestingly,thiourea retained the amino group on the surface of biochar to a great extent due to carbon-sulfur double bond breaking and bonding,which facilitated the formation of pore in the activation process.Significantly,co-doping had no significant improvement effect although nitrogen and sulfur doping separately enhanced the CO_(2) adsorption performance of biochar by 11.9%and 8.5%.The nitrogencontaining and sulfur-containing functional groups in co-doped biochar exhibited mutual inhibition in the process of CO_(2) adsorption.The findings of this study will have pertinent implications in the application of N/S co-doped biochar for CO_(2) adsorption.展开更多
Thermochemical conversion of fossil resources into fuels,chemicals,andmaterials has rapidly increased atmospheric CO_(2)levels,hindering global efforts toward achieving carbon neutrality.With the increasing push for s...Thermochemical conversion of fossil resources into fuels,chemicals,andmaterials has rapidly increased atmospheric CO_(2)levels,hindering global efforts toward achieving carbon neutrality.With the increasing push for sustainability,utilizing electrochemical technology to transform CO_(2)or biomass into value-added chemicals and to close the carbon cycle with sustainable energy sources represents a promising strategy.Expanding the scope of electrosynthesis technology is a prerequisite for the electrification of chemical manufacturing.To this end,constructing the C─N bond is considered a priority.However,a systematic review of electrocatalytic processes toward building C─N bonds using CO_(2)and biomass as carbon sources is not available.Accordingly,this review highlights the research progress in the electrosynthesis of organic nitrogen compounds from CO_(2)and biomass by C─N coupling reactions in view of catalytic materials,focusing on the enlightenment of traditional catalysis on C─N coupling and the understanding of the basis of electrochemical C─N coupling.The possibility of C─N bond in electrocatalysis is also examined from the standpoints of activation of substrates,coupling site,mechanism,and inhibition of hydrogen evolution reaction(HER).Finally,the challenges and prospects of electrocatalytic C─N coupling reactions with improved efficiency and selectivity for future development are discussed.展开更多
This paper presents the synthetic and structure studies of molybdenum（tungsten）-copper-sulphur-dialkyldithiocarbamate cluster compounds.The reactions of（M=Mo,W;n=0,2）,CuCl,and R<sub>2</sub>dtc￣-（R<...This paper presents the synthetic and structure studies of molybdenum（tungsten）-copper-sulphur-dialkyldithiocarbamate cluster compounds.The reactions of（M=Mo,W;n=0,2）,CuCl,and R<sub>2</sub>dtc￣-（R<sub>2</sub>=Me<sub>2</sub>,Et<sub>2</sub>,C<sub>4</sub>H<sub>8</sub>,C<sub>5</sub>H<sub>1</sub>0） yield a series of tetra-,hexa-,and heptanuclear cluster compounds.Their spectroscopic properties and the synthetic reaction mechanism are discussed.展开更多
Ubiquitous competition of stereospecific E2 elimination versus SN2 substitution is of central importance in chemical synthesis.Herein,we uncover how the nature of the leaving group affects the intrinsic competing dyna...Ubiquitous competition of stereospecific E2 elimination versus SN2 substitution is of central importance in chemical synthesis.Herein,we uncover how the nature of the leaving group affects the intrinsic competing dynamics that remains largely unknown as opposed to its role in reactivity.Results are presented for a prototype case of fluoride anion reacting with ethyl chloride,compared to reacting with ethyl iodide.Chemical dynamics simulations reproduce scattering signatures observed in experiments and reveal that the direct stripping/rebound mechanisms characterize the E2/S_(N)2 reactions,in line with their dynamic fingerprints identified.Quite similar structures and energetics are found for the Cl^(−)and I^(−)leaving halides,whereas the competing dynamics show markedly distinct features.A halogen-bonding attraction is found to be crucial that modifies the interaction potential in the entrance channel and essentially tunes the underlying atomistic behaviors causing a mechanistic shift.This work highlights the dynamical effects induced by a leaving group on the proceedings of baseinduced elimination and nucleophilic substitution,providing a unique insight into the reaction selectivity for complex chemical networks and environments.展开更多
基金supported by the State Key Lab of Urban Water Resource and Environment of Harbin Institute of Technology(No.ES202303)the National Natural Science Foundation of China(No.22203039).
文摘The prototypical E2 elimination and SN2 sub-stitution reactions between microsolvated fluoride and ethyl bromide show unexpected dynamic behaviors in mechanistic evolution driven by solvation and collision activation.Considering the steric effects,the gas-phase selectivity favors an E2 pathway barely dependent on collision energies.Remarkably,base solvation steers the reaction in an effective way toward substitution at a near-thermal energy,whereas the governing high-energy events retain elimination.Chemical dynamics simulations reproduce exper-imental findings and uncover a crucial solute-solvent coupling in determining such competing processes.Interestingly,collision activation can tune the underlying atomistic dynamics essentially in the reactant entrance channel and cause a mechanism shift.These features for the ubiquitous competing E2/SN2 dynamics remain quite unknown,providing unique insight into reaction selectivity for complex chemical networks.
基金supported by the National Natural Science Foundation of China(21671011)Beijing High-Level Talent program~~
文摘Ultrathin small MoS2nanosheets exhibit a higher electrocatalytic activity for the hydrogen evolution reaction.However,strong interactions between MoS2layers may result in aggregation;together with the low conductivity of MoS2,this may lower its electrocatalytic activity.In this paper we present a method that we developed to directly produce solid S,N co‐doped carbon(SNC)with a graphite structure and multiple surface groups through a hydrothermal route.When Na2MoO4was added to the reaction,polymolybdate could be anchored into the carbon materials via a chemical interaction that helps polymolybdate disperse uniformly into the SNC.After a high temperature treatment,polymolybdate transformed into MoS2at800°C for6h in a N2atmosphere at a heating rate of5°C/min,owing to S2?being released from the SNC during the treatment(denoted as MoS2/SNC‐800‐6h).The SNC effectively prevents MoS2from aggregating into large particles,and we successfully prepared highly dispersed MoS2in the SNC matrix.Electrochemical characterizations indicate that MoS2/SNC‐900‐12h exhibits a low onset potential of115mV and a low overpotential of237mV at a current density of10mA/cm2.Furthermore,MoS2/SNC‐900‐12h also had an excellent stability with only^2.6%decay at a current density of10mA/cm2after5000test cycles.
基金China Agriculture Research System of MOF and MARA,the Agricultural Science and Technology Innovation Program(ASTIP),National Key R&D Program of China(2022YFD2002102)National Natural Science Foundation of China(52261145701,U21A20162,52376220).
文摘Biochar,as a potential CO_(2) adsorbent,is of great significance in addressing the problem of global warming.Previous studies have demonstrated that the CO_(2) adsorption performance of biochar can be improved by nitrogen and sulfur doping.Co-doping can integrate the structure and function of two elements.However,the physicochemical interaction of nitrogen and sulfur during doping and the CO_(2) adsorption process remains unclear in co-doped biochar.In this study,the heteroatom-doped biochar was prepared with different additives(urea,sodium thiosulfate,and thiourea)via hydrothermal carbonization,and the physicochemical interaction of nitrogen and sulfur in co-doped biochar was investigated extensively.The findings revealed that nitrogen and sulfur competed for limited doped active sites on the carbon skeleton during the co-doping process.Interestingly,thiourea retained the amino group on the surface of biochar to a great extent due to carbon-sulfur double bond breaking and bonding,which facilitated the formation of pore in the activation process.Significantly,co-doping had no significant improvement effect although nitrogen and sulfur doping separately enhanced the CO_(2) adsorption performance of biochar by 11.9%and 8.5%.The nitrogencontaining and sulfur-containing functional groups in co-doped biochar exhibited mutual inhibition in the process of CO_(2) adsorption.The findings of this study will have pertinent implications in the application of N/S co-doped biochar for CO_(2) adsorption.
文摘Thermochemical conversion of fossil resources into fuels,chemicals,andmaterials has rapidly increased atmospheric CO_(2)levels,hindering global efforts toward achieving carbon neutrality.With the increasing push for sustainability,utilizing electrochemical technology to transform CO_(2)or biomass into value-added chemicals and to close the carbon cycle with sustainable energy sources represents a promising strategy.Expanding the scope of electrosynthesis technology is a prerequisite for the electrification of chemical manufacturing.To this end,constructing the C─N bond is considered a priority.However,a systematic review of electrocatalytic processes toward building C─N bonds using CO_(2)and biomass as carbon sources is not available.Accordingly,this review highlights the research progress in the electrosynthesis of organic nitrogen compounds from CO_(2)and biomass by C─N coupling reactions in view of catalytic materials,focusing on the enlightenment of traditional catalysis on C─N coupling and the understanding of the basis of electrochemical C─N coupling.The possibility of C─N bond in electrocatalysis is also examined from the standpoints of activation of substrates,coupling site,mechanism,and inhibition of hydrogen evolution reaction(HER).Finally,the challenges and prospects of electrocatalytic C─N coupling reactions with improved efficiency and selectivity for future development are discussed.
文摘This paper presents the synthetic and structure studies of molybdenum（tungsten）-copper-sulphur-dialkyldithiocarbamate cluster compounds.The reactions of（M=Mo,W;n=0,2）,CuCl,and R<sub>2</sub>dtc￣-（R<sub>2</sub>=Me<sub>2</sub>,Et<sub>2</sub>,C<sub>4</sub>H<sub>8</sub>,C<sub>5</sub>H<sub>1</sub>0） yield a series of tetra-,hexa-,and heptanuclear cluster compounds.Their spectroscopic properties and the synthetic reaction mechanism are discussed.
基金supported by the State Key Lab of Urban Water Resource and Environment of the Harbin Institute of Technology(No.ES202303)。
文摘Ubiquitous competition of stereospecific E2 elimination versus SN2 substitution is of central importance in chemical synthesis.Herein,we uncover how the nature of the leaving group affects the intrinsic competing dynamics that remains largely unknown as opposed to its role in reactivity.Results are presented for a prototype case of fluoride anion reacting with ethyl chloride,compared to reacting with ethyl iodide.Chemical dynamics simulations reproduce scattering signatures observed in experiments and reveal that the direct stripping/rebound mechanisms characterize the E2/S_(N)2 reactions,in line with their dynamic fingerprints identified.Quite similar structures and energetics are found for the Cl^(−)and I^(−)leaving halides,whereas the competing dynamics show markedly distinct features.A halogen-bonding attraction is found to be crucial that modifies the interaction potential in the entrance channel and essentially tunes the underlying atomistic behaviors causing a mechanistic shift.This work highlights the dynamical effects induced by a leaving group on the proceedings of baseinduced elimination and nucleophilic substitution,providing a unique insight into the reaction selectivity for complex chemical networks and environments.
