Molecule geometry structures, frequencies, and energetic stabilities of ammonia borane （AB, NH3BH3 ） and metal amidoboranes （MAB, MNH2BH3）, formed by substituting H atom in AB with one of main group metal atoms, h...Molecule geometry structures, frequencies, and energetic stabilities of ammonia borane （AB, NH3BH3 ） and metal amidoboranes （MAB, MNH2BH3）, formed by substituting H atom in AB with one of main group metal atoms, have been investigated by density-functional theory and optimized at the B3LYP levels with 6-311G＋＋ （3dr, 3pd） basic set. Their structural parameters and infrared spectrum characteristic peaks have been predicted, which should be the criterion of a successfully synthesized material. Several parameters such as binding energies, vibrational frequencies, and the energy gaps between the HOMO and the LUMO have been adopted to characterize and evaluate their structure stabilities. It is also found that the binding energies and HOMO-LUMO energy gaps of the MAB obviously change with the substitution of the atoms. MgAB has the lowest binding energy and is easier to decompose than any other substitutional structures under same conditions, while CaAB has the highest chemical activity.展开更多
The scandocene alkyl complex(C_(5)Me_(5))_(2)ScCH_(2)SiMe_(3)was found to be an efficient catalyst for the dehydrocoupling of the non-cyclic boranes, dicyclohexylborane and thexylborane, with amines under mild conditi...The scandocene alkyl complex(C_(5)Me_(5))_(2)ScCH_(2)SiMe_(3)was found to be an efficient catalyst for the dehydrocoupling of the non-cyclic boranes, dicyclohexylborane and thexylborane, with amines under mild conditions. The reactions afforded the corresponding aminoboranes in high yields with good functional group tolerance. The stoichiometric reaction of scandium alkyl with amine led to the isolation of a scandium amide complex, which was shown to be an active species during the catalysis. Although a boranecoordinated scandium hydride was also obtained from the stoichiometric experiment, it was not involved in the catalytic cycle. In addition, kinetic studies provided insight into this intermolecular dehydrogenation reaction.展开更多
Dehydrocoupling of amines and boranes is an efficient method for the formation of N–B bonds;however,the strong B–H bond dissociation energy(BDE)always restricts non-catalytic reaction pathways.Therefore,alkaline-ear...Dehydrocoupling of amines and boranes is an efficient method for the formation of N–B bonds;however,the strong B–H bond dissociation energy(BDE)always restricts non-catalytic reaction pathways.Therefore,alkaline-earth-metal(Ae)hydrides are used as catalysts for this type of reaction because of their lower Ae–H bond energy.A theoretical study was performed to study the mechanism of Ae-catalyzed dehydrocoupling reactions.The computational results show that such reactions are initiated fromσ-bond metathesis between Ae hydride catalysts and amines to release molecular hydrogen,followed by borane bonding with amino Ae intermediates.Subsequent hydride transfer yields an amino-borane product and,in the process,regenerates the Ae hydride catalyst.Our theoretical calculations revealed that dehydrogenation is the rate-determining step duringσ-bond metathesis in the presence of a magnesium hydride catalyst.We predicted that beryllium hydride could not function as a catalyst because the apparent activation free energy is significantly high.Furthermore,we observed that in calcium or strontium hydride-catalyzed reactions,the rate-limiting step changed to the hydride transfer step.Further density functional theory calculations showed that the BDEs of the Ae–H bond controlled the reactivity of theσ-bond metathesis step.展开更多
Since the initial discovery of alane AlH3in 1942 by Stecher and Wiberg[1],as well as lithium aluminum hydride LiAlH4in 1947 by Finholt,Bond and Schlesinger[2],aluminum hydrides have been ubiquitously utilized in diver...Since the initial discovery of alane AlH3in 1942 by Stecher and Wiberg[1],as well as lithium aluminum hydride LiAlH4in 1947 by Finholt,Bond and Schlesinger[2],aluminum hydrides have been ubiquitously utilized in diverse chemical reactions.They serve as the powerful functional group-reducing reagents,hydrogen sources,and bases[3].展开更多
Using the experimentally known aromatic icosahedral superatoms I_(h)B_(12)H_(12)2−and D_(5d)1,12-C_(2)B_(10)H_(12)as building blocks and based on extensive density functional theory calculations,we predict herein a se...Using the experimentally known aromatic icosahedral superatoms I_(h)B_(12)H_(12)2−and D_(5d)1,12-C_(2)B_(10)H_(12)as building blocks and based on extensive density functional theory calculations,we predict herein a series of core–shell superpolyhedral boranes and carboranes in a bottom-up approach,including the high-symmetry Th B_(12)@B_(152)H_(72)2−(2),C2h C_(2)B_(10)@B_(152)H_(72)(3),D_(3d)B_(12)@B_(144)H_(66)(4),I_(h)B_(12)@C_(24)B_(12)0H_(72)2−(6),and D_(5d)C_(2)B_(10)@C_(24)B_(12)0H_(72)(7).More interestingly,the superatom-assembled linear D2h B_(36)H_(32)^(2−)(8),close-packed planar D_(3d)B_(84)H_(60)^(2−)(10),and nearly close-packed core−shell D_(3d)B_(12)@B144H_(6)6(4)can be extended periodically to form the one-dimensional(1D)α-rhombohedral borane nanowire B_(12)H_(10)(Pmmm)(9),two-dimensional(2D)α-rhombohedral monolayer borophane B_(12)H_(6)(P m1)(11),and the experimentally known three-dimensional(3D)α-rhombohedral boron(R m)(12)which can be viewed as an assembly of the monolayer B_(12)H_(6)(11)staggered in vertical direction,setting up a bottom-up strategy to form low-dimensional boron-based nanomaterials from their borane“seeds”via partial or complete dehydrogenations.Detailed bonding analyses indicate that the high stability of these nanostructures originates from the spherical aromaticity of their icosahedral B_(12)or C_(2)B_(10)structural units which possess the universal skeleton electronic configuration of 1S21P61D101F8 following the Wade’s n+1 rule.The infrared(IR)and Raman spectra of the most-concerned neutral B_(12)@B144H_(6)6(4)and C_(2)B_(10)@C_(24)B_(12)0H_(72)(7)are computationally simulated to facilitate their experimental characterizations.展开更多
Main observation and conclusion In this work,a novel mode for the activation of N-heterocyclic carbene boranes(NHC-boranes)was developed by generating the highly reactive zwitterion species through hydride abstraction...Main observation and conclusion In this work,a novel mode for the activation of N-heterocyclic carbene boranes(NHC-boranes)was developed by generating the highly reactive zwitterion species through hydride abstraction with Lewis acid B(C_(6)F_(5))_(3) in an frustrated Lewis pairs manner.A broad range of alkenes including stilbenes,β-methylstyrenes,styrenes,and alkyl-alkenes were suitable substrates for the B(C_(6)F_(5))_(3)-catalyzed hydroboration to furnish the desired products in good to high yields.Significantly,excellent regioselectivities were obtained in some cases.Mechanistic studies indicate that the B-H bond cleavage is likely involved in the rate-determining step.In addition,an electrophilic addition of NHC-borenium cation to alkenes and the subsequent formation of carbocation are also postulated.The current work provides a promising method for the activation of stable borane adducts,which might lead to some interesting transformations in the future.展开更多
A greener and more convenient alternative to traditional methods for the generation of thiyl radical as hydrogen atom transfer(HAT)catalyst is developed,using molecular oxygen to oxidize thiol without the need for che...A greener and more convenient alternative to traditional methods for the generation of thiyl radical as hydrogen atom transfer(HAT)catalyst is developed,using molecular oxygen to oxidize thiol without the need for chemical initiators or light irradiation.The thiol/oxygen catalysis enables selective and efficient difunctionalization of borane.展开更多
The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary amines.In this paper,we described an asymmetric hydrogenation of phenanthridines using...The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary amines.In this paper,we described an asymmetric hydrogenation of phenanthridines using a chiral mono-alkene-derived borane.A variety of dihydrophenanthridines were furnished in high yields with up to 93%ee.The current catalytic system was very sensitive for the steric hindrance of phenanthridines.Bulky substituents at one phenyl group of phenanthridines were required to obtain the high enantioselectivity.But large substituents on the carbon of the C=N bonds would diminish the reactivity sharply.展开更多
The molecular orbitals obtained from conventional quantum chemistry calculations, are expressed in terms of symmetrized valence bond functions of fragment, and a direct picture of chemical bonding can be drawn easily....The molecular orbitals obtained from conventional quantum chemistry calculations, are expressed in terms of symmetrized valence bond functions of fragment, and a direct picture of chemical bonding can be drawn easily. This method is utilized, together with extended Huckel calculations, to interpret the bonding properties of a centipede-like chain structure for novel laser-producing boranes B3k+pH5k+p+3- which is constructed from the repeated unit B3H5 linked to each other by three B-H-B bonds.展开更多
Hydrolysis of ammonia borane is deemed as a promising technique for robust hydrogen production,yet its deployment is still restricted due to the sluggish kinetics of the water dissociation step.An appropriate catalyst...Hydrolysis of ammonia borane is deemed as a promising technique for robust hydrogen production,yet its deployment is still restricted due to the sluggish kinetics of the water dissociation step.An appropriate catalyst that can effectively reduce the H_(2)O dissociation barrier is quite desirable for sustainable ammonia borane-to-hydrogen conversion.Herein,an amino pre-coordination confinement strategy is profiled to achieve sub-2 nm ordered PtCo intermetallics uniformly on N-doped hollow mesoporous carbon spheres(O-PtCo/NHMS)for ammonia borane catalytic hydrolysis.Such a confined approach showcases the capacity of preventing nanoparticles from agglomeration and growth for accurate size control and can be extended to other ordered intermetallic systems(e.g.PtFe and PtCu).As for the ammonia borane hydrolysis,the ordered PtCo intermetallics have delivered a five times higher turnover frequency activity of 1264.1 min^(-1) than that of the disordered PtCo catalyst,together with excellent catalytic durability.Mechanism studies indicate that the ordered PtCo structure promotes the balanced adsorption of H_(2)O and ammonia borane molecules at Co and Pt sites and reduces the energy barrier for the rate-determining H_(2)O dissociation step to boost the ammonia borane hydrolysis.This work provides valuable insights into the rational design of efficient ordered PtM intermetallic catalysts and expands their application in hydrogen production via ammonia borane hydrolysis.展开更多
We synthesized Ru_(1)Cu_(25)P_(7.5)/TiO_(2)catalyst using sodium borohydride(NaBH_(4))as reductant in a facile strategy.The highly dispersed RuCuP nanoclusters are anchored on the TiO_(2)surface with an average partic...We synthesized Ru_(1)Cu_(25)P_(7.5)/TiO_(2)catalyst using sodium borohydride(NaBH_(4))as reductant in a facile strategy.The highly dispersed RuCuP nanoclusters are anchored on the TiO_(2)surface with an average particle size of 2.62 nm.The catalyst shows excellent catalytic activity when applied to the hydrolysis of AB,which owns a high turnover frequency value of 531.56 mol_(H2)mol_(Ru)^(-1)min^(-1)and a low activation energy of 46.38 kJ·mol^(-1),it also exhibits good durability which maintains 61.13%initial activity after five cycles.The high catalytic performance of Ru_(1)Cu_(25)P_(7.5)/TiO_(2)may be attributed to the synergistic effects between Ru,Cu,and P elements,fine particle size,good dispersion,and the tight adhesion between nanoclusters and carrier.展开更多
Perovskite solar cells have achieved remarkable progress in photovoltaic efficiency.However,interfacial defects at the buried and upper interfaces of perovskite layer remain a critical challenge,leading to charge reco...Perovskite solar cells have achieved remarkable progress in photovoltaic efficiency.However,interfacial defects at the buried and upper interfaces of perovskite layer remain a critical challenge,leading to charge recombination,ion migration,and iodine oxidation.To address this,we propose a novel all-in-one modification strategy employing ammonia borane(BNH6)as a multifunctional complex.By incorporating BNH6 at both buried and upper interfaces simultaneously,we achieve dualinterfacial defect passivation and iodide oxidation suppression through three key mechanisms:(1)hydrolysis-induced interaction with SnO_(2),(2)coordination with Pb^(2+),and(3)inhibition of I−oxidation.This approach significantly enhances device performance,yielding a champion power conversion efficiency(PCE)of 26.43%(certified 25.98%).Furthermore,the unencapsulated device demonstrates prominent enhanced operation stability,maintaining 90%of its initial PCE after 500 h under continuous illumination.Notably,our strategy eliminates the need for separate interface treatments,streamlining fabrication and offering a scalable route toward high-performance perovskite photovoltaics.展开更多
Reaction of the N-heterocyclic borane [MeCCHC（CHe）（NAr）2]Btt （1, Ar=2,6-Me2C6H3） with B（C6F5）3 af- forded the zwitterionic hydroborane [MeCCHC（CHz）B（C6F5）3（NAr）2]BH, in which the β-methyl group can be d...Reaction of the N-heterocyclic borane [MeCCHC（CHe）（NAr）2]Btt （1, Ar=2,6-Me2C6H3） with B（C6F5）3 af- forded the zwitterionic hydroborane [MeCCHC（CHz）B（C6F5）3（NAr）2]BH, in which the β-methyl group can be deprotonated with LiN（SiMe3）2 to yield an anionic zwitterionic borenium.展开更多
An amide-substituted quinuclidine-borane has been identified as a more efficient hydridic hydrogen atom transfer(HAT)catalyst for the hydroalkylation of unactivated olefins under visible-light irradiation.^(1)H NMR ti...An amide-substituted quinuclidine-borane has been identified as a more efficient hydridic hydrogen atom transfer(HAT)catalyst for the hydroalkylation of unactivated olefins under visible-light irradiation.^(1)H NMR titration experiments reveal that the amide moiety of the quinuclidine-borane catalyst forms stronger hydrogen bonds with the carbonyl substrates,thereby improving the reaction yields.Furthermore,it was found that the reaction yields correlate well with the association constant between the quinuclidine-borane catalyst and the carbonyl substrate.A scale-up reaction using a continuous-flow photoreactor has also been demonstrated.展开更多
Developing cost-effective and high-activity catalysts for the methanolysis of ammonia borane(AB)has attracted great attention in the field of hydrogen energy recently.Besides the modification of the electronic structu...Developing cost-effective and high-activity catalysts for the methanolysis of ammonia borane(AB)has attracted great attention in the field of hydrogen energy recently.Besides the modification of the electronic structure of the catalysts,external factors such as visible light irradiation can improve the efficiency of hydrogen production as well.In the present study,a Z-scheme heterostructured VO-Cu_(0.5)Ni_(0.5)O catalysts were constructed by introducing a plenteous phase interface and oxygen vacancy(Vo).The catalytic activity of as-prepared VO-Cu_(0.5)Ni_(0.5)O toward AB methanolysis has been improved dramatically with the assistance of visible light irradiation.The turnover frequency(TOF)under visible light irradiation was measured to be 29_(mol)H_(2)·mol_(cat.)^(-1)·min^(-1),which is 1.4 times larger than the TOF in the absence of visible light.Systematic characterization experiments and density functional theory(DFT)calculations were conducted to unveil the causation of enhanced catalytic activity.The results demonstrated that the enhancement of the catalytic activity of VO-Cu_(0.5)Ni_(0.5)O originated from the electronic structure modification induced by the formation of heterojunctions,the introduction of oxygen vacancies,and the assistance of visible light cooperatively.The formation of heterojunction and the introduction of oxygen vacancies provoked the upshift of the d-band center;while the visible light irradiation induced the photogenerated electrons to transfer from Cu to Ni sites at the interface.Such electron structure modulation is beneficial for the construction of abundant active sites,thereby enhancing the adsorption of methanol on the Ni sites,which is considered as the rate-determine step for the methanolysis of AB.The strong interaction between Ni and O weakened the O-H bond of methanol,accelerating the methanolysis of AB.These results demonstrate the utilization of combined heterojunction,oxygen vacancy,and visible light to explore highly active AB methanolysis catalysts,which should shed light on the exploration of more effective catalysts for AB methanolysis.展开更多
Ultrafine,highly dispersed Pt clusters were immobilized onto the Co nanoparticle surfaces by one-step pyrolysis of the precursor Pt(Ⅱ)-encapsulating Co-MOF-74.Owing to the small size effects of Pt clusters as well as...Ultrafine,highly dispersed Pt clusters were immobilized onto the Co nanoparticle surfaces by one-step pyrolysis of the precursor Pt(Ⅱ)-encapsulating Co-MOF-74.Owing to the small size effects of Pt clusters as well as the strongly enhanced synergistic interactions between Pt and Co atoms,the obtained Pt-on-Co/C400 catalysts exhib-ited excellent catalytic activity toward the hydrolysis of ammonia borane with an extremely high turnover frequency(TOF)value of 3022 min^(-1)at 303 K.Durability test indicated that the obtained Pt-on-Co/C400 catalysts possessed high catalytic stability,and there were no changes in the catalyst structures and catalytic activities after 10 cycles.展开更多
Ammonia borane(AB)has received much attention as an environmentally friendly,non-toxic,room temperature stable hydrogen storage material with high hydrogen content of 19.6%.However,its hydrolysis for hydrogen producti...Ammonia borane(AB)has received much attention as an environmentally friendly,non-toxic,room temperature stable hydrogen storage material with high hydrogen content of 19.6%.However,its hydrolysis for hydrogen production at room-temperature is kinetically slow and requires precious metal catalysts.In this work,it is found that the prepared Raney Ni W-r treated with high concentration of NaOH(6.25 mol/L)at 110℃exhibited excellent catalytic performance for AB hydrolysis at room temperature.The Raney Ni W-r can promote the AB complete hydrolysis within 60 s under basic condition at small sized trials,even higher than that of the 20%Pt/C catalyst.Its apparent activation energy at room temperature is only 26.6 kJ/mol and the turnover frequency(TOF)value is as high as 51.42 min-1.Owing to its high density and magnetic properties,the catalyst is very easy for magnetic separation.Furthermore,possible mechanism of the hydrolytic reaction of AB based on experimental results is proposed.As a well-established industrial catalyst,Raney Ni has been prepared on a large scale at low cost.This study provides a promising pathway for the large-scale preparation of low-cost and recyclable catalysts for AB hydrolysis.展开更多
The efficient and cost-effective implementation of ammonia borane(AB)hydrolysis dehydrogenation for hydrogen storage is crucial.This study investigated the role of solid acid Amberlyst-15(A-15)for hydrogen evolution f...The efficient and cost-effective implementation of ammonia borane(AB)hydrolysis dehydrogenation for hydrogen storage is crucial.This study investigated the role of solid acid Amberlyst-15(A-15)for hydrogen evolution from AB hydrolysis.Notably,AB hydrogen evolution rate can reach 194.15 ml·min^(-1)at 30℃,with a low apparent activation energy of 8.20 kJ·mol^(-1).After five cycles of reuse,the reaction involving A-15 could keep a conversion rate of about 93%.The AB hydrolysis follows quasi first-order kinetics with respect to the AB concentration and quasi zero-order kinetics with respect to the A-15 mass.According to the characterization results of XRD,ATR-FTIR,and in-situ MS,the boric acid was the dominant hydrolyzate,while water as a hydrogen donor in this reaction.Furthermore,based on the reasoning that hydrogen bonds between A-15 and AB(aq)promotes the diffusion of AB,release of H2 and the cleavage of O-H bond of H2O,a possible mechanism was proposed.展开更多
Efficient water dissociation catalysts are important for reducing the activation energy barrier of water molecules in the field of energy conversio n.Herein,symmetry-bro ken Rh ensemble induced by mandated charge was ...Efficient water dissociation catalysts are important for reducing the activation energy barrier of water molecules in the field of energy conversio n.Herein,symmetry-bro ken Rh ensemble induced by mandated charge was established to boost the catalytic activity toward water dissociation.As an experimental verification,the turnover frequency of 1.0-RTO_(V4)in hydrogen generation from ammonia borane hydrolysis reaches up to 2838 min-1(24828 min^(-1)depend on Rh dispersion),exceeding the benchmark set up by state-of-the-art catalysts.The transfer of mandated charge from O_(V)to Rh near O_(V)breaks the local symmetry of Rh nanoparticle and forms Rh^(γ-)(electron-aggregation Rh)-Rh interfacial atomic ensemble.This symmetry-broken Rh ensemble is the reason for the high activity of the catalyst.This work provides an effective electronic regulation strategy based on symmetry-broken atomic ensemble induced by mandated charge,designed to stimulate the limiting activity of metal catalyst in the field of next generation energy chemistry.展开更多
The high hydrogen desorption density(19.6 wt%)of ammonia borane(AB)makes it one of the most promising chemical hydrogen storage materials.Developing cost-effective catalysts is the key for accelerating the hydrolysis ...The high hydrogen desorption density(19.6 wt%)of ammonia borane(AB)makes it one of the most promising chemical hydrogen storage materials.Developing cost-effective catalysts is the key for accelerating the hydrolysis of AB.Herein,we present a straightforward synthesis method for the Cu_(2)O decorated CoO catalyst derived from ZIF-67 precursors using carbothermal shock(~1 s)in air.The obtained results demonstrate that a small amount of Cu_(2)O doping into CoO synergistically enhances AB hydrolysis,resulting in an almost fivefold increase in turnover frequency(TOF=97 molH_(2)molCoO-1min-1at 298 K).Further studies indicated that the incorporation of Cu_(2)O alters the electronic distribution of the surface of catalysts,introducing more oxygen vacancies and increasing the pyridinic nitrogen content.The increased oxygen vacancies effectively enhanced the adsorption and activation ability of active sites for reactants(H_(2)O and AB),while the targeting effect of pyridinic nitrogen enhances the dispersion of the catalyst.Theoretical analysis reveals that CoO plays a key role in the dissociation of H_(2)O,while minor doping with Cu_(2)O substantially reduces the dissociation energy barrier of AB.This research provides a novel strategy for the design and efficient preparation of AB hydrolysis catalysts for efficient hydrogen production.展开更多
文摘Molecule geometry structures, frequencies, and energetic stabilities of ammonia borane （AB, NH3BH3 ） and metal amidoboranes （MAB, MNH2BH3）, formed by substituting H atom in AB with one of main group metal atoms, have been investigated by density-functional theory and optimized at the B3LYP levels with 6-311G＋＋ （3dr, 3pd） basic set. Their structural parameters and infrared spectrum characteristic peaks have been predicted, which should be the criterion of a successfully synthesized material. Several parameters such as binding energies, vibrational frequencies, and the energy gaps between the HOMO and the LUMO have been adopted to characterize and evaluate their structure stabilities. It is also found that the binding energies and HOMO-LUMO energy gaps of the MAB obviously change with the substitution of the atoms. MgAB has the lowest binding energy and is easier to decompose than any other substitutional structures under same conditions, while CaAB has the highest chemical activity.
基金supported by the National Natural Science Foundation of China (No. 21871204)。
文摘The scandocene alkyl complex(C_(5)Me_(5))_(2)ScCH_(2)SiMe_(3)was found to be an efficient catalyst for the dehydrocoupling of the non-cyclic boranes, dicyclohexylborane and thexylborane, with amines under mild conditions. The reactions afforded the corresponding aminoboranes in high yields with good functional group tolerance. The stoichiometric reaction of scandium alkyl with amine led to the isolation of a scandium amide complex, which was shown to be an active species during the catalysis. Although a boranecoordinated scandium hydride was also obtained from the stoichiometric experiment, it was not involved in the catalytic cycle. In addition, kinetic studies provided insight into this intermolecular dehydrogenation reaction.
基金supported by the National Science Foundation of China(Grants 21372266 and 21772020)the Fundamental Research Funds for the Central Universities(Chongqing University)(No.106112017CDJXY220007)+1 种基金We are also thankful for the project supported by the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJ1703048)the Graduate Scientific Research and Innovation Foundation of Chongqing,China(No.CYB16034).
文摘Dehydrocoupling of amines and boranes is an efficient method for the formation of N–B bonds;however,the strong B–H bond dissociation energy(BDE)always restricts non-catalytic reaction pathways.Therefore,alkaline-earth-metal(Ae)hydrides are used as catalysts for this type of reaction because of their lower Ae–H bond energy.A theoretical study was performed to study the mechanism of Ae-catalyzed dehydrocoupling reactions.The computational results show that such reactions are initiated fromσ-bond metathesis between Ae hydride catalysts and amines to release molecular hydrogen,followed by borane bonding with amino Ae intermediates.Subsequent hydride transfer yields an amino-borane product and,in the process,regenerates the Ae hydride catalyst.Our theoretical calculations revealed that dehydrogenation is the rate-determining step duringσ-bond metathesis in the presence of a magnesium hydride catalyst.We predicted that beryllium hydride could not function as a catalyst because the apparent activation free energy is significantly high.Furthermore,we observed that in calcium or strontium hydride-catalyzed reactions,the rate-limiting step changed to the hydride transfer step.Further density functional theory calculations showed that the BDEs of the Ae–H bond controlled the reactivity of theσ-bond metathesis step.
基金supported by the Nanyang Technological University(NTU),Nippon Shokubai and the Singapore Ministry of Education(MOET2EP10220-0002)。
文摘Since the initial discovery of alane AlH3in 1942 by Stecher and Wiberg[1],as well as lithium aluminum hydride LiAlH4in 1947 by Finholt,Bond and Schlesinger[2],aluminum hydrides have been ubiquitously utilized in diverse chemical reactions.They serve as the powerful functional group-reducing reagents,hydrogen sources,and bases[3].
基金supported by the National Natural Science Foundation of China(Nos.22373061,21973057,and 22003034).
文摘Using the experimentally known aromatic icosahedral superatoms I_(h)B_(12)H_(12)2−and D_(5d)1,12-C_(2)B_(10)H_(12)as building blocks and based on extensive density functional theory calculations,we predict herein a series of core–shell superpolyhedral boranes and carboranes in a bottom-up approach,including the high-symmetry Th B_(12)@B_(152)H_(72)2−(2),C2h C_(2)B_(10)@B_(152)H_(72)(3),D_(3d)B_(12)@B_(144)H_(66)(4),I_(h)B_(12)@C_(24)B_(12)0H_(72)2−(6),and D_(5d)C_(2)B_(10)@C_(24)B_(12)0H_(72)(7).More interestingly,the superatom-assembled linear D2h B_(36)H_(32)^(2−)(8),close-packed planar D_(3d)B_(84)H_(60)^(2−)(10),and nearly close-packed core−shell D_(3d)B_(12)@B144H_(6)6(4)can be extended periodically to form the one-dimensional(1D)α-rhombohedral borane nanowire B_(12)H_(10)(Pmmm)(9),two-dimensional(2D)α-rhombohedral monolayer borophane B_(12)H_(6)(P m1)(11),and the experimentally known three-dimensional(3D)α-rhombohedral boron(R m)(12)which can be viewed as an assembly of the monolayer B_(12)H_(6)(11)staggered in vertical direction,setting up a bottom-up strategy to form low-dimensional boron-based nanomaterials from their borane“seeds”via partial or complete dehydrogenations.Detailed bonding analyses indicate that the high stability of these nanostructures originates from the spherical aromaticity of their icosahedral B_(12)or C_(2)B_(10)structural units which possess the universal skeleton electronic configuration of 1S21P61D101F8 following the Wade’s n+1 rule.The infrared(IR)and Raman spectra of the most-concerned neutral B_(12)@B144H_(6)6(4)and C_(2)B_(10)@C_(24)B_(12)0H_(72)(7)are computationally simulated to facilitate their experimental characterizations.
基金the financial support from the National Natural Science Foundation of China(Nos.21871269 and 21521002).
文摘Main observation and conclusion In this work,a novel mode for the activation of N-heterocyclic carbene boranes(NHC-boranes)was developed by generating the highly reactive zwitterion species through hydride abstraction with Lewis acid B(C_(6)F_(5))_(3) in an frustrated Lewis pairs manner.A broad range of alkenes including stilbenes,β-methylstyrenes,styrenes,and alkyl-alkenes were suitable substrates for the B(C_(6)F_(5))_(3)-catalyzed hydroboration to furnish the desired products in good to high yields.Significantly,excellent regioselectivities were obtained in some cases.Mechanistic studies indicate that the B-H bond cleavage is likely involved in the rate-determining step.In addition,an electrophilic addition of NHC-borenium cation to alkenes and the subsequent formation of carbocation are also postulated.The current work provides a promising method for the activation of stable borane adducts,which might lead to some interesting transformations in the future.
基金supported by research start-up fund(Project No.4933621)from the Chinese University of Hong Kong.Mr.Weixuan Sun is thanked for checking the experimental procedure。
文摘A greener and more convenient alternative to traditional methods for the generation of thiyl radical as hydrogen atom transfer(HAT)catalyst is developed,using molecular oxygen to oxidize thiol without the need for chemical initiators or light irradiation.The thiol/oxygen catalysis enables selective and efficient difunctionalization of borane.
基金financial support from the National Natural Science Foundation of China(21825108 and 22331011).
文摘The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary amines.In this paper,we described an asymmetric hydrogenation of phenanthridines using a chiral mono-alkene-derived borane.A variety of dihydrophenanthridines were furnished in high yields with up to 93%ee.The current catalytic system was very sensitive for the steric hindrance of phenanthridines.Bulky substituents at one phenyl group of phenanthridines were required to obtain the high enantioselectivity.But large substituents on the carbon of the C=N bonds would diminish the reactivity sharply.
基金Project supported financially by the National Natural Science Foundation of China.
文摘The molecular orbitals obtained from conventional quantum chemistry calculations, are expressed in terms of symmetrized valence bond functions of fragment, and a direct picture of chemical bonding can be drawn easily. This method is utilized, together with extended Huckel calculations, to interpret the bonding properties of a centipede-like chain structure for novel laser-producing boranes B3k+pH5k+p+3- which is constructed from the repeated unit B3H5 linked to each other by three B-H-B bonds.
基金National Natural Science Foundation of China(Grants Nos.92266107,92366207,52401245,and 52371236)the China Manned Space Station program(JZ-20190104)+3 种基金Technology Innovation Leading Program of Shaanxi Province(2024QCY-KXJ-011)Science Fund for Distinguished Young Scholars of Shaanxi Province(No.2025JC-JCQN-001)Major Scientific and Technological Innovation Special Plan of Xianyang Science and Technology Plan Project(No.L2024-ZDKJ-ZDCGZH-0026)the Fundamental Research Funds for the Central Universities.
文摘Hydrolysis of ammonia borane is deemed as a promising technique for robust hydrogen production,yet its deployment is still restricted due to the sluggish kinetics of the water dissociation step.An appropriate catalyst that can effectively reduce the H_(2)O dissociation barrier is quite desirable for sustainable ammonia borane-to-hydrogen conversion.Herein,an amino pre-coordination confinement strategy is profiled to achieve sub-2 nm ordered PtCo intermetallics uniformly on N-doped hollow mesoporous carbon spheres(O-PtCo/NHMS)for ammonia borane catalytic hydrolysis.Such a confined approach showcases the capacity of preventing nanoparticles from agglomeration and growth for accurate size control and can be extended to other ordered intermetallic systems(e.g.PtFe and PtCu).As for the ammonia borane hydrolysis,the ordered PtCo intermetallics have delivered a five times higher turnover frequency activity of 1264.1 min^(-1) than that of the disordered PtCo catalyst,together with excellent catalytic durability.Mechanism studies indicate that the ordered PtCo structure promotes the balanced adsorption of H_(2)O and ammonia borane molecules at Co and Pt sites and reduces the energy barrier for the rate-determining H_(2)O dissociation step to boost the ammonia borane hydrolysis.This work provides valuable insights into the rational design of efficient ordered PtM intermetallic catalysts and expands their application in hydrogen production via ammonia borane hydrolysis.
基金Funded by the National Natural Science Foundation of China(No.21805217)the Fundamental Research Funds for the Central Universities(WUT:2019IVB014 and 2021IVA014)。
文摘We synthesized Ru_(1)Cu_(25)P_(7.5)/TiO_(2)catalyst using sodium borohydride(NaBH_(4))as reductant in a facile strategy.The highly dispersed RuCuP nanoclusters are anchored on the TiO_(2)surface with an average particle size of 2.62 nm.The catalyst shows excellent catalytic activity when applied to the hydrolysis of AB,which owns a high turnover frequency value of 531.56 mol_(H2)mol_(Ru)^(-1)min^(-1)and a low activation energy of 46.38 kJ·mol^(-1),it also exhibits good durability which maintains 61.13%initial activity after five cycles.The high catalytic performance of Ru_(1)Cu_(25)P_(7.5)/TiO_(2)may be attributed to the synergistic effects between Ru,Cu,and P elements,fine particle size,good dispersion,and the tight adhesion between nanoclusters and carrier.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.22334007).
文摘Perovskite solar cells have achieved remarkable progress in photovoltaic efficiency.However,interfacial defects at the buried and upper interfaces of perovskite layer remain a critical challenge,leading to charge recombination,ion migration,and iodine oxidation.To address this,we propose a novel all-in-one modification strategy employing ammonia borane(BNH6)as a multifunctional complex.By incorporating BNH6 at both buried and upper interfaces simultaneously,we achieve dualinterfacial defect passivation and iodide oxidation suppression through three key mechanisms:(1)hydrolysis-induced interaction with SnO_(2),(2)coordination with Pb^(2+),and(3)inhibition of I−oxidation.This approach significantly enhances device performance,yielding a champion power conversion efficiency(PCE)of 26.43%(certified 25.98%).Furthermore,the unencapsulated device demonstrates prominent enhanced operation stability,maintaining 90%of its initial PCE after 500 h under continuous illumination.Notably,our strategy eliminates the need for separate interface treatments,streamlining fabrication and offering a scalable route toward high-performance perovskite photovoltaics.
基金We are grateful to the National Natural Science Foundation of China （Grant Nos. 21390401 and 21472098） and 973 Program （Grant No. 2012CB821600） for support of this work.
文摘Reaction of the N-heterocyclic borane [MeCCHC（CHe）（NAr）2]Btt （1, Ar=2,6-Me2C6H3） with B（C6F5）3 af- forded the zwitterionic hydroborane [MeCCHC（CHz）B（C6F5）3（NAr）2]BH, in which the β-methyl group can be deprotonated with LiN（SiMe3）2 to yield an anionic zwitterionic borenium.
基金the National Natural Science Foundation of China(grant nos.22371180 and 22001163 to Y.J.and 22361032 to H.Z.)Shanghai Jiao Tong University(SJTU)is acknowledged.Dr.Pandaram Sakthivel(SJTU)is acknowledged for reproducing the results of compounds 6,10,and 21.
文摘An amide-substituted quinuclidine-borane has been identified as a more efficient hydridic hydrogen atom transfer(HAT)catalyst for the hydroalkylation of unactivated olefins under visible-light irradiation.^(1)H NMR titration experiments reveal that the amide moiety of the quinuclidine-borane catalyst forms stronger hydrogen bonds with the carbonyl substrates,thereby improving the reaction yields.Furthermore,it was found that the reaction yields correlate well with the association constant between the quinuclidine-borane catalyst and the carbonyl substrate.A scale-up reaction using a continuous-flow photoreactor has also been demonstrated.
基金supported the Natural Science Foundation of Guangdong Province(Nos.2022A1515140085,2022A1515111022 and 2022A1515110275)the Major and Special Project in the Field of Intelligent Manufacturing of the Universities in Guangdong Province(No.2020ZDZX2067)+2 种基金the Natural Science Foundation of Huizhou University(No.HZU202004)the Professorial and Doctoral Scientific Research Foundation of Huizhou University(No.2020JB046)the Open Project Program of Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices,Huizhou University(No.EFMDN2021004M).
文摘Developing cost-effective and high-activity catalysts for the methanolysis of ammonia borane(AB)has attracted great attention in the field of hydrogen energy recently.Besides the modification of the electronic structure of the catalysts,external factors such as visible light irradiation can improve the efficiency of hydrogen production as well.In the present study,a Z-scheme heterostructured VO-Cu_(0.5)Ni_(0.5)O catalysts were constructed by introducing a plenteous phase interface and oxygen vacancy(Vo).The catalytic activity of as-prepared VO-Cu_(0.5)Ni_(0.5)O toward AB methanolysis has been improved dramatically with the assistance of visible light irradiation.The turnover frequency(TOF)under visible light irradiation was measured to be 29_(mol)H_(2)·mol_(cat.)^(-1)·min^(-1),which is 1.4 times larger than the TOF in the absence of visible light.Systematic characterization experiments and density functional theory(DFT)calculations were conducted to unveil the causation of enhanced catalytic activity.The results demonstrated that the enhancement of the catalytic activity of VO-Cu_(0.5)Ni_(0.5)O originated from the electronic structure modification induced by the formation of heterojunctions,the introduction of oxygen vacancies,and the assistance of visible light cooperatively.The formation of heterojunction and the introduction of oxygen vacancies provoked the upshift of the d-band center;while the visible light irradiation induced the photogenerated electrons to transfer from Cu to Ni sites at the interface.Such electron structure modulation is beneficial for the construction of abundant active sites,thereby enhancing the adsorption of methanol on the Ni sites,which is considered as the rate-determine step for the methanolysis of AB.The strong interaction between Ni and O weakened the O-H bond of methanol,accelerating the methanolysis of AB.These results demonstrate the utilization of combined heterojunction,oxygen vacancy,and visible light to explore highly active AB methanolysis catalysts,which should shed light on the exploration of more effective catalysts for AB methanolysis.
文摘Ultrafine,highly dispersed Pt clusters were immobilized onto the Co nanoparticle surfaces by one-step pyrolysis of the precursor Pt(Ⅱ)-encapsulating Co-MOF-74.Owing to the small size effects of Pt clusters as well as the strongly enhanced synergistic interactions between Pt and Co atoms,the obtained Pt-on-Co/C400 catalysts exhib-ited excellent catalytic activity toward the hydrolysis of ammonia borane with an extremely high turnover frequency(TOF)value of 3022 min^(-1)at 303 K.Durability test indicated that the obtained Pt-on-Co/C400 catalysts possessed high catalytic stability,and there were no changes in the catalyst structures and catalytic activities after 10 cycles.
基金supported by the National Natural Science Foundation of China(21908135)Natural Science Foundation of Shanxi Datong University(2022K23)+1 种基金Graduate Research Innovation and Practice Innovation Projects of Shanxi Datong University(23CX31)Postgraduate Educational Reform and Research Program of Shanxi Datong University(23JG07)。
文摘Ammonia borane(AB)has received much attention as an environmentally friendly,non-toxic,room temperature stable hydrogen storage material with high hydrogen content of 19.6%.However,its hydrolysis for hydrogen production at room-temperature is kinetically slow and requires precious metal catalysts.In this work,it is found that the prepared Raney Ni W-r treated with high concentration of NaOH(6.25 mol/L)at 110℃exhibited excellent catalytic performance for AB hydrolysis at room temperature.The Raney Ni W-r can promote the AB complete hydrolysis within 60 s under basic condition at small sized trials,even higher than that of the 20%Pt/C catalyst.Its apparent activation energy at room temperature is only 26.6 kJ/mol and the turnover frequency(TOF)value is as high as 51.42 min-1.Owing to its high density and magnetic properties,the catalyst is very easy for magnetic separation.Furthermore,possible mechanism of the hydrolytic reaction of AB based on experimental results is proposed.As a well-established industrial catalyst,Raney Ni has been prepared on a large scale at low cost.This study provides a promising pathway for the large-scale preparation of low-cost and recyclable catalysts for AB hydrolysis.
基金support from the National Natural Science Foundation of China(22222808,21978200,22208330)the Postdoctoral Fellowship Programof CPSF(GZC20241204)+1 种基金the China Postdoctoral Science Foundation-Tianjin Joint Support Program(2023T022TJ)the Haihe Laboratory of Sustainable Chemical Transformations for financial support.
文摘The efficient and cost-effective implementation of ammonia borane(AB)hydrolysis dehydrogenation for hydrogen storage is crucial.This study investigated the role of solid acid Amberlyst-15(A-15)for hydrogen evolution from AB hydrolysis.Notably,AB hydrogen evolution rate can reach 194.15 ml·min^(-1)at 30℃,with a low apparent activation energy of 8.20 kJ·mol^(-1).After five cycles of reuse,the reaction involving A-15 could keep a conversion rate of about 93%.The AB hydrolysis follows quasi first-order kinetics with respect to the AB concentration and quasi zero-order kinetics with respect to the A-15 mass.According to the characterization results of XRD,ATR-FTIR,and in-situ MS,the boric acid was the dominant hydrolyzate,while water as a hydrogen donor in this reaction.Furthermore,based on the reasoning that hydrogen bonds between A-15 and AB(aq)promotes the diffusion of AB,release of H2 and the cleavage of O-H bond of H2O,a possible mechanism was proposed.
基金supported by the National Natural Science Foundation of China(No.22279118,No.22309164)the China Postdoctoral Science Foundation(No.2023M733214)+1 种基金the Young Top Talent Program of Zhongyuan-Yingcai-Jihua(No.30602674)the Special Projects of Henan Province Key Research and Development and Promotion(Science and Technology Research)(No.232102241033)。
文摘Efficient water dissociation catalysts are important for reducing the activation energy barrier of water molecules in the field of energy conversio n.Herein,symmetry-bro ken Rh ensemble induced by mandated charge was established to boost the catalytic activity toward water dissociation.As an experimental verification,the turnover frequency of 1.0-RTO_(V4)in hydrogen generation from ammonia borane hydrolysis reaches up to 2838 min-1(24828 min^(-1)depend on Rh dispersion),exceeding the benchmark set up by state-of-the-art catalysts.The transfer of mandated charge from O_(V)to Rh near O_(V)breaks the local symmetry of Rh nanoparticle and forms Rh^(γ-)(electron-aggregation Rh)-Rh interfacial atomic ensemble.This symmetry-broken Rh ensemble is the reason for the high activity of the catalyst.This work provides an effective electronic regulation strategy based on symmetry-broken atomic ensemble induced by mandated charge,designed to stimulate the limiting activity of metal catalyst in the field of next generation energy chemistry.
基金financially supported by the National Natural Science Foundation of China(No.52301276)Zhejiang Provincial Natural Science Foundation of China(No.24E010001)+2 种基金Lishui Science and Technology Plan Project(No.2023GYX09)the support of the National Natural Science Foundation of China(52371229)Shanghai High-level Talent start funding
文摘The high hydrogen desorption density(19.6 wt%)of ammonia borane(AB)makes it one of the most promising chemical hydrogen storage materials.Developing cost-effective catalysts is the key for accelerating the hydrolysis of AB.Herein,we present a straightforward synthesis method for the Cu_(2)O decorated CoO catalyst derived from ZIF-67 precursors using carbothermal shock(~1 s)in air.The obtained results demonstrate that a small amount of Cu_(2)O doping into CoO synergistically enhances AB hydrolysis,resulting in an almost fivefold increase in turnover frequency(TOF=97 molH_(2)molCoO-1min-1at 298 K).Further studies indicated that the incorporation of Cu_(2)O alters the electronic distribution of the surface of catalysts,introducing more oxygen vacancies and increasing the pyridinic nitrogen content.The increased oxygen vacancies effectively enhanced the adsorption and activation ability of active sites for reactants(H_(2)O and AB),while the targeting effect of pyridinic nitrogen enhances the dispersion of the catalyst.Theoretical analysis reveals that CoO plays a key role in the dissociation of H_(2)O,while minor doping with Cu_(2)O substantially reduces the dissociation energy barrier of AB.This research provides a novel strategy for the design and efficient preparation of AB hydrolysis catalysts for efficient hydrogen production.
