With reduced dehydrogenation enthalpy change and reduced dehydrogenation temperature compared with its phenol-cyclohexanol pair,sodium phenoxide-cyclohexanolate pair developed recently is promising for large-scale ene...With reduced dehydrogenation enthalpy change and reduced dehydrogenation temperature compared with its phenol-cyclohexanol pair,sodium phenoxide-cyclohexanolate pair developed recently is promising for large-scale energy storage and long-distance hydrogen transportation.In the present work,we investigate the kinetic behavior of the pair in the hydrogenation and dehydrogenation in water over three commercial catalysts.It is shown that 5%Ru/Al2O3 and 5%Pt/C perform well in the hydrogenation and dehydrogenation,respectively.Kinetic analyses show that the hydrogenation of sodium phenoxide is of first-order with respect to H2 pressure and zero-order to the concentration of sodium phenoxide in the presence of Ru/Al2O3 catalyst.>99%conversion of cyclohexanol and>99%selectivity to phenoxide can be achieved in the dehydrogenation catalyzed by Pt/C catalyst and in the presence of Na OH at 100℃,where cyclohexanone was observed as an intermediate.According to the kinetic analysis,the hydrogenation of sodium phenoxide may undergo the hydrolysis and hydrogenation pathway.For the dehydrogenation,an intermediate,i.e.,cyclohexanone,was detected and two possible pathways are proposed accordingly.展开更多
This paper presents the catalytic effect of NaH doped nanocrystalline TiO_(2)(designated as NaTiOxH)in the improvement of MgH_(2)hydrogen storage properties.The catalyst preparation involves ball milling NaH with TiO_...This paper presents the catalytic effect of NaH doped nanocrystalline TiO_(2)(designated as NaTiOxH)in the improvement of MgH_(2)hydrogen storage properties.The catalyst preparation involves ball milling NaH with TiO_(2)for 3 hr.The addition of 5 wt%NaTiOxH powder into MgH_(2)reduces its operating temperature to∼185℃,which is∼110℃lower than the additive-free as-milled MgH_(2).The composite remarkably desorbs∼7.2 wt%H_(2)within 15 min at∼290℃and reabsorbs∼4.5 wt%H_(2)in 45 min at room temperature under 50 bar H_(2).MgH_(2)dehydrogenation is activated at 57 kJ/mol by the catalyst.More importantly,the addition of 2.5 wt%NaTiOxH catalyst aids MgH_(2)to reversibly produce∼6.1 wt%H_(2)upon 100 cycles within 475 hr at 300℃.Microstructural investigation into the catalyzed MgH_(2)composite reveals a firm contact existing between NaTiOxH and MgH_(2)particles.Meanwhile,the NaTiOxH catalyst consists of catalytically active Ti_(3)O_(5),and“rod-like”Na_(2)Ti_(3)O_(7)species liberated in-situ during preparation;these active species could provide multiple hydrogen diffusion pathways for an improved MgH_(2)sorption process.Furthermore,the elemental characterization identifies the reduced valence states of titanium(Ti<4+)which show some sort of reversibility consistent with H_(2)insertion and removal.This phenomenon is believed to enhance the mobility of Mg/MgH_(2)electrons by the creation and elimination of oxygen vacancies in the defective(TiO_(2-x))catalyst.Our findings have therefore moved MgH_(2)closer to practical applications.展开更多
The development of efficient hydrogen storage materials is one of the biggest technical challenges for the coming ＂hydrogen economy＂. The liquid organic hydrogen carriers （LOHCs） with high hydrogen contents, rever...The development of efficient hydrogen storage materials is one of the biggest technical challenges for the coming ＂hydrogen economy＂. The liquid organic hydrogen carriers （LOHCs） with high hydrogen contents, reversibilities and moderate dehydrogenation kinetics have been considered as an alternative option supplementing the extensively investigated inorganic hydride systems. In this review, LOHCs for long distance H2 transport and for onboard application will be discussed with the focuses of the design and development of LOHCs and their hydrogenation ＆ dehydrogenation catalyses.展开更多
One of the major obstacles to the application of potassium-ion batteries in large-scale energy storage is the lack of safe and effective electrolytes.KNH_(2),a new potassium-ion solid electrolyte has been developed in...One of the major obstacles to the application of potassium-ion batteries in large-scale energy storage is the lack of safe and effective electrolytes.KNH_(2),a new potassium-ion solid electrolyte has been developed in this study.Its ionic conductivity reaches 4.84×10^(-5)S cm^(-1)at 150°C and can reach3.56×10^(-4)S cm^(-1)after mechanochemical treatment.The result from electron paramagnetic resonance(EPR) measurement shows that the increment of ionic conductivity is dependent on the concentration of nitrogen defects in the KNH_(2) electrolyte.To the best of our knowledge,this is the first report that adopts inorganic amide as an electrolyte for potassium-ion battery and initiates the search for a new amidebased solid electrolyte for an all-solid-state potassium-ion battery.展开更多
CONSPECTUS:Hydrogen storage for onboard applications has been recognized as a grand challenge for the large-scale implementation of hydrogen fuel cell vehicles.Tremendous research efforts have thus been devoted to the...CONSPECTUS:Hydrogen storage for onboard applications has been recognized as a grand challenge for the large-scale implementation of hydrogen fuel cell vehicles.Tremendous research efforts have thus been devoted to the design and development of hydrides of lightweight elements(HLEs).A prominent feature of these materials is the indispensable ingredient of alkali/alkaline earth cations.Alkali alkaline earth metals(AMs)are highly reactive and have a rich coordination chemistry.As a matter of fact,an AM cation can form a complete range of compounds with hydrogenous anions,such as H−,[NH2]−,[BH4]−,[AlH4]−,[NH2BH3]−,[TMHX]−,[R-CH2−NH]−,[R-CH2−O]−,etc.,and,thus,tune the Al−H,N−H,B−H,and C−H bond strengths for hydrogen storage.In this Account,our research efforts in the development of AM amide-hydride composites,AM amidoboranes,and metalorganic hydrides for hydrogen storage are reviewed.A partial substitution of the H in NH3 by AM gives rise to solid AM amides or imides.Those compounds can react with AM hydride(AMH)to produce H2.This is driven by the redox reaction between a protic H(N)and hydridic H(AM).A variety of amide-hydride composites holding promise for hydrogen storage were thus developed,including LiNH2-hydride,Mg(NH2)2-hydride,and complex amide-hydride composites.For amidoboranes,the substitution of H(N)in ammonia borane(AB)by AM transforms the molecular crystal AB into amidoboranes with an ionic crystal structure,leading to significant changes in terms of charge distribution,bond length,intermolecular forces,and so on,which in turn results in enhanced dehydrogenation properties.For metalorganic hydrides,through reacting AM compounds(usually AM hydride)with aliphatic,carbocyclic,or heterocyclic organic hydrides having“reactive protic H”,corresponding metalorganic hydrides are formed.Because of the electron-donating nature of AM,the strengths of the C−H bond in metal-organic hydrides can be modulated.For each material system,we will introduce the synthesis of materials,show their performances,correlate the hydrogen storage property to a crystal and/or electronic structure,and especially highlight the functions of AM in tuning the thermodynamic and/or kinetic properties of HLEs.At the end of the Account,challenges and a future research direction of the hydrogen storage field are discussed.展开更多
基金financial support from the project of the National Natural Science Foundation of China(51671178,21875246)the project from DICP(DICP ZZBS201616)the support from Sino-Japanese Research Cooperative Program of Ministry of Science and Technology(2016YFE0118300) and iChEM·2011
文摘With reduced dehydrogenation enthalpy change and reduced dehydrogenation temperature compared with its phenol-cyclohexanol pair,sodium phenoxide-cyclohexanolate pair developed recently is promising for large-scale energy storage and long-distance hydrogen transportation.In the present work,we investigate the kinetic behavior of the pair in the hydrogenation and dehydrogenation in water over three commercial catalysts.It is shown that 5%Ru/Al2O3 and 5%Pt/C perform well in the hydrogenation and dehydrogenation,respectively.Kinetic analyses show that the hydrogenation of sodium phenoxide is of first-order with respect to H2 pressure and zero-order to the concentration of sodium phenoxide in the presence of Ru/Al2O3 catalyst.>99%conversion of cyclohexanol and>99%selectivity to phenoxide can be achieved in the dehydrogenation catalyzed by Pt/C catalyst and in the presence of Na OH at 100℃,where cyclohexanone was observed as an intermediate.According to the kinetic analysis,the hydrogenation of sodium phenoxide may undergo the hydrolysis and hydrogenation pathway.For the dehydrogenation,an intermediate,i.e.,cyclohexanone,was detected and two possible pathways are proposed accordingly.
基金The authors acknowledge the Project supported by the National Key R&D Program of China(2019YFE0103600,2018YFB1502101)the Key R&D Program of Shandong Province,China(2020CXGC010402)+4 种基金the National Natural Science Foundation of China(51801197)the Liaoning Revitalization Talents Program(XLYC2002076)the Dalian High-level Talents Program(2019RD09)the Youth Innovation Promotion Association CAS(2019189)K.C.Wong Education Foundation(GJTD-2018–06).
文摘This paper presents the catalytic effect of NaH doped nanocrystalline TiO_(2)(designated as NaTiOxH)in the improvement of MgH_(2)hydrogen storage properties.The catalyst preparation involves ball milling NaH with TiO_(2)for 3 hr.The addition of 5 wt%NaTiOxH powder into MgH_(2)reduces its operating temperature to∼185℃,which is∼110℃lower than the additive-free as-milled MgH_(2).The composite remarkably desorbs∼7.2 wt%H_(2)within 15 min at∼290℃and reabsorbs∼4.5 wt%H_(2)in 45 min at room temperature under 50 bar H_(2).MgH_(2)dehydrogenation is activated at 57 kJ/mol by the catalyst.More importantly,the addition of 2.5 wt%NaTiOxH catalyst aids MgH_(2)to reversibly produce∼6.1 wt%H_(2)upon 100 cycles within 475 hr at 300℃.Microstructural investigation into the catalyzed MgH_(2)composite reveals a firm contact existing between NaTiOxH and MgH_(2)particles.Meanwhile,the NaTiOxH catalyst consists of catalytically active Ti_(3)O_(5),and“rod-like”Na_(2)Ti_(3)O_(7)species liberated in-situ during preparation;these active species could provide multiple hydrogen diffusion pathways for an improved MgH_(2)sorption process.Furthermore,the elemental characterization identifies the reduced valence states of titanium(Ti<4+)which show some sort of reversibility consistent with H_(2)insertion and removal.This phenomenon is believed to enhance the mobility of Mg/MgH_(2)electrons by the creation and elimination of oxygen vacancies in the defective(TiO_(2-x))catalyst.Our findings have therefore moved MgH_(2)closer to practical applications.
基金supported by the Project of the National Natural Science Funds for Distinguished Young Scholar(51225206)Projects of the National Natural Science Foundation of China(grant nos.U1232120,51301161,21473181 and 51472237)
文摘The development of efficient hydrogen storage materials is one of the biggest technical challenges for the coming ＂hydrogen economy＂. The liquid organic hydrogen carriers （LOHCs） with high hydrogen contents, reversibilities and moderate dehydrogenation kinetics have been considered as an alternative option supplementing the extensively investigated inorganic hydride systems. In this review, LOHCs for long distance H2 transport and for onboard application will be discussed with the focuses of the design and development of LOHCs and their hydrogenation ＆ dehydrogenation catalyses.
基金supported by the Key R&D Program of Shandong Province China (2020CXGC010402)the National Natural Science Foundation of China (51801197)+3 种基金the Youth Innovation Promotion Association CAS (2019189)the Liaoning Revitalization Talents Program (XLYC2002076)the Dalian High-level Talents Program (2019RD09)the K.C. Wong Education Foundation (GJTD2018-06)。
文摘One of the major obstacles to the application of potassium-ion batteries in large-scale energy storage is the lack of safe and effective electrolytes.KNH_(2),a new potassium-ion solid electrolyte has been developed in this study.Its ionic conductivity reaches 4.84×10^(-5)S cm^(-1)at 150°C and can reach3.56×10^(-4)S cm^(-1)after mechanochemical treatment.The result from electron paramagnetic resonance(EPR) measurement shows that the increment of ionic conductivity is dependent on the concentration of nitrogen defects in the KNH_(2) electrolyte.To the best of our knowledge,this is the first report that adopts inorganic amide as an electrolyte for potassium-ion battery and initiates the search for a new amidebased solid electrolyte for an all-solid-state potassium-ion battery.
基金support provided by National Key R&D Program of China(2018YFB1502101,2019YFE0103600)the National Natural Science Foundation of China(21875246,51801197)+3 种基金LiaoNing Revitalization Talents Program(XLYC1807157)Youth Innovation Promo-tion Association CAS(2019189)K.C.Wong Education Foundation(GJTD-2018-06)Dalian High-Level Talents Program(2019RD09)。
文摘CONSPECTUS:Hydrogen storage for onboard applications has been recognized as a grand challenge for the large-scale implementation of hydrogen fuel cell vehicles.Tremendous research efforts have thus been devoted to the design and development of hydrides of lightweight elements(HLEs).A prominent feature of these materials is the indispensable ingredient of alkali/alkaline earth cations.Alkali alkaline earth metals(AMs)are highly reactive and have a rich coordination chemistry.As a matter of fact,an AM cation can form a complete range of compounds with hydrogenous anions,such as H−,[NH2]−,[BH4]−,[AlH4]−,[NH2BH3]−,[TMHX]−,[R-CH2−NH]−,[R-CH2−O]−,etc.,and,thus,tune the Al−H,N−H,B−H,and C−H bond strengths for hydrogen storage.In this Account,our research efforts in the development of AM amide-hydride composites,AM amidoboranes,and metalorganic hydrides for hydrogen storage are reviewed.A partial substitution of the H in NH3 by AM gives rise to solid AM amides or imides.Those compounds can react with AM hydride(AMH)to produce H2.This is driven by the redox reaction between a protic H(N)and hydridic H(AM).A variety of amide-hydride composites holding promise for hydrogen storage were thus developed,including LiNH2-hydride,Mg(NH2)2-hydride,and complex amide-hydride composites.For amidoboranes,the substitution of H(N)in ammonia borane(AB)by AM transforms the molecular crystal AB into amidoboranes with an ionic crystal structure,leading to significant changes in terms of charge distribution,bond length,intermolecular forces,and so on,which in turn results in enhanced dehydrogenation properties.For metalorganic hydrides,through reacting AM compounds(usually AM hydride)with aliphatic,carbocyclic,or heterocyclic organic hydrides having“reactive protic H”,corresponding metalorganic hydrides are formed.Because of the electron-donating nature of AM,the strengths of the C−H bond in metal-organic hydrides can be modulated.For each material system,we will introduce the synthesis of materials,show their performances,correlate the hydrogen storage property to a crystal and/or electronic structure,and especially highlight the functions of AM in tuning the thermodynamic and/or kinetic properties of HLEs.At the end of the Account,challenges and a future research direction of the hydrogen storage field are discussed.
