Two-dimensional(2D)materials loaded with single atoms and clusters are being set at the forefront of catalysis due to their distinctive geometric and electronic features.However,the usually-complicated synthesis proce...Two-dimensional(2D)materials loaded with single atoms and clusters are being set at the forefront of catalysis due to their distinctive geometric and electronic features.However,the usually-complicated synthesis procedures impede in-depth clarification of their catalytic mechanisms.To this end,herein we developed an efficient one-step dimension-reduction carbonization strategy,with which we successfully architected a highly-efficient catalyst for oxygen reduction reaction(ORR),featured with symbiotic cobalt single atoms and clusters decorated in two-dimensional(2D)ultra-thin(3.5 nm thickness)nitrogen-carbon nanosheets.The synergistic effects of the two components afford excellent oxygen reduction activity in alkaline media(E_(1/2)=0.823 V vs.RHE)and thereof a high power density(146.61 mW cm^(-2))in an assembled Zn-air battery.As revealed by theoretical calculations,the cobalt clusters can regulate electrons surrounding those individual atoms and affect the adsorption of intermediate species.As a consequence,the derived active sites of single cobalt atoms lead to a significant improvement of the ORR performance.Thus,our work may fuel interests to delicate architectu re of single atoms and clusters coexisting 2D support toward optimal electrocatalytic performance.展开更多
Imparting one-dimensional(1D)ultrafine organic nanowires with tailored ligands and atomically-dispersed central noble metal to craft high-performance hybrid single atom electrocatalysts offers a prospective yet challe...Imparting one-dimensional(1D)ultrafine organic nanowires with tailored ligands and atomically-dispersed central noble metal to craft high-performance hybrid single atom electrocatalysts offers a prospective yet challenging approach for the advancement in hydrogen evolution reactions(HER).Herein,we report the evaporation-induced self-assembly of sequence-defined amphiphilic alternating azopeptoids(AAAPs)to generate photo-responsive and micron-scale ultrafine peptoid nanowires(UFPNWs)with a diameter of~1.8 nm via pendants'hydrophobic conjugate stacking mechanism,exemplifying the finest biomimetic polymers-based nanowires to date.A series of 1D UFPNWs-based single-atom catalysts(SACs)were meticulously fabricated using the chelation interaction between Pt ions and nitrogenous ligands.The photo-controllable electrocatalytic performance was evaluated toward acidic HER,which was highly dependent on the presence of Pt elements,the structural characteristic of supports,and the peripheral coordination microenvironment of the center Pt atoms.Notably,the Pt-based hybrid SACs using terpyridine-modified UFPNWs as support presented favorable electrocatalytic capacity with an overpotential of~20 m V at a current density of 10 m A cm^(-2),and a mass activity of 89.6 times greater than commercial Pt/C catalyst.Our work paves an appealing avenue for the construction of stimuli-responsive 1D organic nanowire-based hybrid catalysts with controllable electrocatalytic HER performance.展开更多
Galvanic replacement, co-impregnation and sequential impregnation have been employed to prepare Pd-Cu bimetallic catalysts with less than 1 wt-% Cu and ca. 0.03 wt-% Pd for selective hydrogenation of acetylene in exce...Galvanic replacement, co-impregnation and sequential impregnation have been employed to prepare Pd-Cu bimetallic catalysts with less than 1 wt-% Cu and ca. 0.03 wt-% Pd for selective hydrogenation of acetylene in excess ethylene. High angle annular dark field-scanning transmission electron microscopy （HAADF-STEM） and H2 chemisorption results confirmed that Pd-Cu singleatom alloy structures were constructed in all three bimetallic catalysts. Catalytic tests indicated that when the conversion of acetylene was above 99%, the selectivity of ethylene of these three single atom alloy catalysts was still more than 73%. Furthermore, the single atom alloy catalyst prepared by sequential incipient wetness impregnation was found to have the best stability among the three procedures used.展开更多
In our experiment, a single cesium atom prepared in a large-magnetic-gradient magneto optical trap （MOT） can be efficiently transferred into a 1064-nm far-off-resonance microscopic optical dipole trap （FORT）. The ...In our experiment, a single cesium atom prepared in a large-magnetic-gradient magneto optical trap （MOT） can be efficiently transferred into a 1064-nm far-off-resonance microscopic optical dipole trap （FORT）. The efficient transfer of the single atom between the two traps is used to determine the trapping lifetime and the effective temperature of the single atom in FORT. The typical trapping lifetime has been improved from ~ 6.9 s to ~ 130 s by decreasing the background pressure from 1 × 10^-10 Torr to ~ 2 × 10^-11 Torr and applying one-shot 10-ms laser cooling phase. We also theoretically investigate the dependence of trapping lifetimes of a single atom in a FORT on trap parameters based on the FORT beam＇s intensity noise induced heating. Numerical simulations show that the heating depends on the FORT beam＇s waist size and the trap depth. The trapping time can be predicted based on effective temperature measurement of a single atom in the FORT and the intensity noise spectra of the FORT beam. These experimental results are found to be in agreement with the predictions of the heating model.展开更多
Platinum(Pt)-based materials are still the most efficient and practical catalysts to drive the sluggish kinetics of cathodic oxygen reduction reaction(ORR)in proton exchange membrane fuel cells(PEMFCs).However,their c...Platinum(Pt)-based materials are still the most efficient and practical catalysts to drive the sluggish kinetics of cathodic oxygen reduction reaction(ORR)in proton exchange membrane fuel cells(PEMFCs).However,their catalysis and stability performance still need to be further improved in terms of corrosion of both carbon support and Pt catalyst particles as well as Pt loading reduction.Based on the developed synthetic strategies of alloying/nanostructuring Pt particles and modifying/innovating supports in developing conventional Pt-based catalysts,Pt single-atom catalysts(Pt SACs)as the recently burgeoning hot materials with a potential to achieve the maximum utilization of Pt are comprehensively reviewed in this paper.The design thoughts and synthesis of various isolated,alloyed,and nanoparticlecontained Pt SACs are summarized.The single-atomic Pt coordinating with non-metals and alloying with metals as well as the metal-support interactions of Pt single-atoms with carbon/non-carbon supports are emphasized in terms of the ORR activity and stability of the catalysts.To advance further research and development of Pt SACs for viable implementation in PEMFCs,various technical challenges and several potential research directions are outlined.展开更多
We systematically investigated the catalytic performance of 3d,4d,and 5d transition metals anchored onto two-dimensional extended porphyrin(PP)substrates as nitrogen reduction reaction(NRR)electrocatalysts,employing d...We systematically investigated the catalytic performance of 3d,4d,and 5d transition metals anchored onto two-dimensional extended porphyrin(PP)substrates as nitrogen reduction reaction(NRR)electrocatalysts,employing density functional theory(DFT)calculations and four-step high-throughput screening.Four novel metalloporphyrin(MPP,M=Zr,Nb,Hf,and Re)single-atom catalyst candidates have been identified due to their excellent catalytic performance(low onset potential,high stability,and selectivity).Through comprehensive reaction path search,the maximum Gibbs free energy changes for NRR on the ZrPP(enzymatic-consecutive hybrid path),NbPP(consecutive path),HfPP(enzymatic-consecutive hybrid path),and RePP(distal path)catalysts are 0.38,0.41,0.53,and 0.53 eV,respectively.Band structures,projected density of states,and charge/spin distributions show that the high catalytic activity is due to significant orbital hybridizations and charge transfer between N_(2)and MPP catalysts.We hope our work will promote experimental synthesis of these NRR electrocatalysts and provide new opportunities to the electrochemical conversion of N_(2)to NH_(3)under ambient conditions.展开更多
Developing innovative and efficient non-precious-metal-group(non-PMG)electrocatalysts is crucial for the wide use of zinc-air batteries(ZABs).Herein,a single-atom catalyst(termed as Fe-N-C/rGO SAC)with unique five N-c...Developing innovative and efficient non-precious-metal-group(non-PMG)electrocatalysts is crucial for the wide use of zinc-air batteries(ZABs).Herein,a single-atom catalyst(termed as Fe-N-C/rGO SAC)with unique five N-coordinated Fe(Fe-N_(5))centers is prepared by pyrolyzing the composite of zeolitic-imidazolate-frameworks-8(ZIF-8)and graphene oxide(GO).Specifically,the individual Fe site is stabilized by four equatorial and one axial N atoms donated by the N-doped carbon matrix and imidazole ring,respectively,thus forming an asymmetric electron depletion zone over the metal center,which can effectively promote the generation of reactive intermediates and accelerate the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)processes for ZABs.The rechargeable liquid ZAB with Fe-N-C/rGO catalyst exhibits an extremely high energy density(928.25 Wh·kg^(−1)),a remarkable peak power density(107.12 mW·cm^(−2)),and a long cycle life(400 h).Additionally,the corresponding flexible solid-state ZAB displays superior foldability and remarkable cycling stability.This work provides both experimental and theoretical guidance for rational design of non-PMG electrocatalyst-driven ZABs.展开更多
Designing highly selective and efficient singleatom electrocatalysts is essential for ammonia production under ambient conditions. This paper describes a density functional theory study on exploring the performance tr...Designing highly selective and efficient singleatom electrocatalysts is essential for ammonia production under ambient conditions. This paper describes a density functional theory study on exploring the performance trends of transition metal complexes with P-based ligands in nitrogen reduction reaction(NRR) and further develops a design principle for high-performance single-atom catalysts(SACs)of NRR. Among the explored catalysts, W@BP(0.40 eV),Ta@BP(0.47 eV), and Nb@BP(0.53 eV) are identified as remarkable candidates with low free energy change in the potential-limiting step, high stability and high electrical conductivity for NRR. It is worth noting that almost all SACs with P-based ligands exhibit high NRR selectivity, due to the fact that they adsorb *N_(2) more strongly than *H. The adsorption free energy of *N_(2) H can be considered as a descriptor for the intrinsic activity trends in NRR. Furthermore, by constructing a volcano plot of the activity against the electronic charge on metal centers, it is demonstrated that the metal center with a moderate amount of positive charge can promote the catalytic performance of NRR.展开更多
Developing acid/base-resistant and low-price microwave-absorbing materials with lighter weight is highly desired for practical applications in extreme environments.Herein,we demonstrate the successful synthesis of the...Developing acid/base-resistant and low-price microwave-absorbing materials with lighter weight is highly desired for practical applications in extreme environments.Herein,we demonstrate the successful synthesis of the N-doped porous carbon(NC)material with hierarchical pore structure by the spray pyrolysis method.The large specific surface area(SBET=707.53 m^(2)·g^(−1))of materials enables multiple scattering of incident electromagnetic waves,and N doping greatly enhances the electrical conductivity of the material.Notably,single-atom Zn can adjust the local electronic structure of adjacent sites such as carbon and nitrogen atoms,induce the center of polarization,and thus change the dielectric and electronic properties of the host material.The porous carbon coating of single-atom Zn avoids the deterioration of electromagnetic parameters caused by the accumulation of magnetic particles under high-temperature pyrolysis.At the same time,they can also be used in various complex environments,such as acidic and basic environments.Ultimately,NC-1000,with high surface area,low density,and good chemical stability,obtained a minimum reflection loss(RLmin)of−50.5 dB and an effective absorption bandwidth(EAB)exceeding 5.1 GHz at the thickness of 1.9 mm.After soaking in the strong acid and base solution,the electromagnetic wave absorption performance of the material decreased by<15%.Widely available raw materials and a simple preparation scheme are expected to expedite industrial mass production for this novel type of materials.展开更多
基金supported by the National Natural Science Foundation of China(51872115 and 12234018)Beijing Synchrotron Radiation Facility(BSRF)4B9A.
文摘Two-dimensional(2D)materials loaded with single atoms and clusters are being set at the forefront of catalysis due to their distinctive geometric and electronic features.However,the usually-complicated synthesis procedures impede in-depth clarification of their catalytic mechanisms.To this end,herein we developed an efficient one-step dimension-reduction carbonization strategy,with which we successfully architected a highly-efficient catalyst for oxygen reduction reaction(ORR),featured with symbiotic cobalt single atoms and clusters decorated in two-dimensional(2D)ultra-thin(3.5 nm thickness)nitrogen-carbon nanosheets.The synergistic effects of the two components afford excellent oxygen reduction activity in alkaline media(E_(1/2)=0.823 V vs.RHE)and thereof a high power density(146.61 mW cm^(-2))in an assembled Zn-air battery.As revealed by theoretical calculations,the cobalt clusters can regulate electrons surrounding those individual atoms and affect the adsorption of intermediate species.As a consequence,the derived active sites of single cobalt atoms lead to a significant improvement of the ORR performance.Thus,our work may fuel interests to delicate architectu re of single atoms and clusters coexisting 2D support toward optimal electrocatalytic performance.
基金supported by the National Natural Science Foundation of China(52373114,52073092,22231007,22001071)。
文摘Imparting one-dimensional(1D)ultrafine organic nanowires with tailored ligands and atomically-dispersed central noble metal to craft high-performance hybrid single atom electrocatalysts offers a prospective yet challenging approach for the advancement in hydrogen evolution reactions(HER).Herein,we report the evaporation-induced self-assembly of sequence-defined amphiphilic alternating azopeptoids(AAAPs)to generate photo-responsive and micron-scale ultrafine peptoid nanowires(UFPNWs)with a diameter of~1.8 nm via pendants'hydrophobic conjugate stacking mechanism,exemplifying the finest biomimetic polymers-based nanowires to date.A series of 1D UFPNWs-based single-atom catalysts(SACs)were meticulously fabricated using the chelation interaction between Pt ions and nitrogenous ligands.The photo-controllable electrocatalytic performance was evaluated toward acidic HER,which was highly dependent on the presence of Pt elements,the structural characteristic of supports,and the peripheral coordination microenvironment of the center Pt atoms.Notably,the Pt-based hybrid SACs using terpyridine-modified UFPNWs as support presented favorable electrocatalytic capacity with an overpotential of~20 m V at a current density of 10 m A cm^(-2),and a mass activity of 89.6 times greater than commercial Pt/C catalyst.Our work paves an appealing avenue for the construction of stimuli-responsive 1D organic nanowire-based hybrid catalysts with controllable electrocatalytic HER performance.
文摘Galvanic replacement, co-impregnation and sequential impregnation have been employed to prepare Pd-Cu bimetallic catalysts with less than 1 wt-% Cu and ca. 0.03 wt-% Pd for selective hydrogenation of acetylene in excess ethylene. High angle annular dark field-scanning transmission electron microscopy （HAADF-STEM） and H2 chemisorption results confirmed that Pd-Cu singleatom alloy structures were constructed in all three bimetallic catalysts. Catalytic tests indicated that when the conversion of acetylene was above 99%, the selectivity of ethylene of these three single atom alloy catalysts was still more than 73%. Furthermore, the single atom alloy catalyst prepared by sequential incipient wetness impregnation was found to have the best stability among the three procedures used.
基金Acknowledgements This work was supported by the Na- tional Natural Science Foundation of China （Grant Nos. 60978017, 61078051, and 10974125）, the project from excellent research team from the National Natural Science Foundation of China （Grant No. 60821004）, and the NCET Program from the Ministry of Educa- tion of China （Grant No. NCET-07-0524）.
文摘In our experiment, a single cesium atom prepared in a large-magnetic-gradient magneto optical trap （MOT） can be efficiently transferred into a 1064-nm far-off-resonance microscopic optical dipole trap （FORT）. The efficient transfer of the single atom between the two traps is used to determine the trapping lifetime and the effective temperature of the single atom in FORT. The typical trapping lifetime has been improved from ~ 6.9 s to ~ 130 s by decreasing the background pressure from 1 × 10^-10 Torr to ~ 2 × 10^-11 Torr and applying one-shot 10-ms laser cooling phase. We also theoretically investigate the dependence of trapping lifetimes of a single atom in a FORT on trap parameters based on the FORT beam＇s intensity noise induced heating. Numerical simulations show that the heating depends on the FORT beam＇s waist size and the trap depth. The trapping time can be predicted based on effective temperature measurement of a single atom in the FORT and the intensity noise spectra of the FORT beam. These experimental results are found to be in agreement with the predictions of the heating model.
基金supported by the National Natural Science Foundation of China(Grant No.22272105)the Natural Science Foundation of Shanghai(Grant No.23ZR1423900).
文摘Platinum(Pt)-based materials are still the most efficient and practical catalysts to drive the sluggish kinetics of cathodic oxygen reduction reaction(ORR)in proton exchange membrane fuel cells(PEMFCs).However,their catalysis and stability performance still need to be further improved in terms of corrosion of both carbon support and Pt catalyst particles as well as Pt loading reduction.Based on the developed synthetic strategies of alloying/nanostructuring Pt particles and modifying/innovating supports in developing conventional Pt-based catalysts,Pt single-atom catalysts(Pt SACs)as the recently burgeoning hot materials with a potential to achieve the maximum utilization of Pt are comprehensively reviewed in this paper.The design thoughts and synthesis of various isolated,alloyed,and nanoparticlecontained Pt SACs are summarized.The single-atomic Pt coordinating with non-metals and alloying with metals as well as the metal-support interactions of Pt single-atoms with carbon/non-carbon supports are emphasized in terms of the ORR activity and stability of the catalysts.To advance further research and development of Pt SACs for viable implementation in PEMFCs,various technical challenges and several potential research directions are outlined.
基金C.-X.H.,S.-Y.L.,C.L.,and L.-M.Y.gratefully acknowledge support from the National Natural Science Foundation of China(Nos.22073033,21873032,21673087,and 21903032)the startup fund(Nos.2006013118 and 3004013105)from Huazhong University of Science and Technology,the Fundamental Research Funds for the Central Universities(No.2019kfyRCPY116)+1 种基金the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003)C.-X.H.,S.-Y.L.,and G.-L.L.gratefully acknowledge support from Guangdong Basic and Applied Basic Research Foundation(No.2021A1515010382).
文摘We systematically investigated the catalytic performance of 3d,4d,and 5d transition metals anchored onto two-dimensional extended porphyrin(PP)substrates as nitrogen reduction reaction(NRR)electrocatalysts,employing density functional theory(DFT)calculations and four-step high-throughput screening.Four novel metalloporphyrin(MPP,M=Zr,Nb,Hf,and Re)single-atom catalyst candidates have been identified due to their excellent catalytic performance(low onset potential,high stability,and selectivity).Through comprehensive reaction path search,the maximum Gibbs free energy changes for NRR on the ZrPP(enzymatic-consecutive hybrid path),NbPP(consecutive path),HfPP(enzymatic-consecutive hybrid path),and RePP(distal path)catalysts are 0.38,0.41,0.53,and 0.53 eV,respectively.Band structures,projected density of states,and charge/spin distributions show that the high catalytic activity is due to significant orbital hybridizations and charge transfer between N_(2)and MPP catalysts.We hope our work will promote experimental synthesis of these NRR electrocatalysts and provide new opportunities to the electrochemical conversion of N_(2)to NH_(3)under ambient conditions.
基金the National Natural Science Foundation of China(Nos.22078028,22078027,and 21978026).
文摘Developing innovative and efficient non-precious-metal-group(non-PMG)electrocatalysts is crucial for the wide use of zinc-air batteries(ZABs).Herein,a single-atom catalyst(termed as Fe-N-C/rGO SAC)with unique five N-coordinated Fe(Fe-N_(5))centers is prepared by pyrolyzing the composite of zeolitic-imidazolate-frameworks-8(ZIF-8)and graphene oxide(GO).Specifically,the individual Fe site is stabilized by four equatorial and one axial N atoms donated by the N-doped carbon matrix and imidazole ring,respectively,thus forming an asymmetric electron depletion zone over the metal center,which can effectively promote the generation of reactive intermediates and accelerate the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)processes for ZABs.The rechargeable liquid ZAB with Fe-N-C/rGO catalyst exhibits an extremely high energy density(928.25 Wh·kg^(−1)),a remarkable peak power density(107.12 mW·cm^(−2)),and a long cycle life(400 h).Additionally,the corresponding flexible solid-state ZAB displays superior foldability and remarkable cycling stability.This work provides both experimental and theoretical guidance for rational design of non-PMG electrocatalyst-driven ZABs.
基金supported by the National Natural Science Foundation of China (21525626 and 21761132023)the Program of Introducing Talents of Discipline to Universities (BP0618007)。
文摘Designing highly selective and efficient singleatom electrocatalysts is essential for ammonia production under ambient conditions. This paper describes a density functional theory study on exploring the performance trends of transition metal complexes with P-based ligands in nitrogen reduction reaction(NRR) and further develops a design principle for high-performance single-atom catalysts(SACs)of NRR. Among the explored catalysts, W@BP(0.40 eV),Ta@BP(0.47 eV), and Nb@BP(0.53 eV) are identified as remarkable candidates with low free energy change in the potential-limiting step, high stability and high electrical conductivity for NRR. It is worth noting that almost all SACs with P-based ligands exhibit high NRR selectivity, due to the fact that they adsorb *N_(2) more strongly than *H. The adsorption free energy of *N_(2) H can be considered as a descriptor for the intrinsic activity trends in NRR. Furthermore, by constructing a volcano plot of the activity against the electronic charge on metal centers, it is demonstrated that the metal center with a moderate amount of positive charge can promote the catalytic performance of NRR.
基金B.X.thanks financial support from the National Natural Science Foundation of China(No.21801133)the Jiangsu Specially Appointed Professorship and Innovation and Entrepreneurship Talents in Jiangsu Province,the State Key Laboratory of Coordination Chemistry,the School of Chemistry and Chemical Engineering,and Collaborative Innovation Center of Advanced Microstructures,Nanjing University.
文摘Developing acid/base-resistant and low-price microwave-absorbing materials with lighter weight is highly desired for practical applications in extreme environments.Herein,we demonstrate the successful synthesis of the N-doped porous carbon(NC)material with hierarchical pore structure by the spray pyrolysis method.The large specific surface area(SBET=707.53 m^(2)·g^(−1))of materials enables multiple scattering of incident electromagnetic waves,and N doping greatly enhances the electrical conductivity of the material.Notably,single-atom Zn can adjust the local electronic structure of adjacent sites such as carbon and nitrogen atoms,induce the center of polarization,and thus change the dielectric and electronic properties of the host material.The porous carbon coating of single-atom Zn avoids the deterioration of electromagnetic parameters caused by the accumulation of magnetic particles under high-temperature pyrolysis.At the same time,they can also be used in various complex environments,such as acidic and basic environments.Ultimately,NC-1000,with high surface area,low density,and good chemical stability,obtained a minimum reflection loss(RLmin)of−50.5 dB and an effective absorption bandwidth(EAB)exceeding 5.1 GHz at the thickness of 1.9 mm.After soaking in the strong acid and base solution,the electromagnetic wave absorption performance of the material decreased by<15%.Widely available raw materials and a simple preparation scheme are expected to expedite industrial mass production for this novel type of materials.
