In this paper, two recurrence formulas for radial average values of N-dimensional hydrogen atom are derived. Explicit expressions for <n rJ N-2 |r s|n rJ N-2 > are given for 3≥s≥-6. These results can be applie...In this paper, two recurrence formulas for radial average values of N-dimensional hydrogen atom are derived. Explicit expressions for <n rJ N-2 |r s|n rJ N-2 > are given for 3≥s≥-6. These results can be applied to discuss average value of centrifugal potential energy and other physical quantities. The relevant results of the usual hydrogen atom are contained in more general conclusion of this paper as special cases.展开更多
In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix eleme...In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix elements are also derived.展开更多
Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and selectivity.However,most of the reported SA catalysts are...Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and selectivity.However,most of the reported SA catalysts are fixed through the strong bonding between the dispersed single metallic atoms with nonmetallic atoms of the substrates,which greatly limits the controllable regulation of electrocatalytic activity of SA catalysts.In this work,Pt-Ni bonded Pt SA catalyst with adjustable electronic states was successfully constructed through a controllable electrochemical reduction on the coordination unsaturated amorphous Ni(OH)_(2)nanosheet arrays.Based on the X-ray absorption fine structure analysis and first-principles calculations,Pt SA was bonded with Ni sites of amorphous Ni(OH)_(2),rather than conventional O sites,resulting in negatively charged Pt^(δ-).In situ Raman spectroscopy revealed that the changed configuration and electronic states greatly enhanced absorbability for activated hydrogen atoms,which were the essential intermediate for alkaline hydrogen evolution reaction.The hydrogen spillover process was revealed from amorphous Ni(OH)_(2)that effectively cleave the H-O-H bond of H_(2)O and produce H atom to the Pt SA sites,leading to a low overpotential of 48 mV in alkaline electrolyte at-1000 mA cm^(-2)mg^(-1)_(Pt),evidently better than commercial Pt/C catalysts.This work provided new strategy for the control-lable modulation of the local structure of SA catalysts and the systematic regulation of the electronic states.展开更多
Strategically designing the electrocatalytic system and cleverly inducing strain is an effective approach to balance the cost and activity of Pt-based electrocatalysts for industrial-scale hydrogen production.Herein,w...Strategically designing the electrocatalytic system and cleverly inducing strain is an effective approach to balance the cost and activity of Pt-based electrocatalysts for industrial-scale hydrogen production.Herein,we present a unipolar pulsed electrodeposition(UPED) strategy to induce strain in the Ni lattice by introducing trace amounts of Pt single atoms(SAs)(0.22 wt%).The overpotential decreased by 183 mV at 10 mA cm^(-2) in 1.0 M KOH after introducing trace amounts of Pt_(SAs).The industrial electrolyzer,assembled with Pt_(SAs)Ni cathode and a commercial NiFeO_(x) anode,requires a cell voltage of 1.90 V to attain 1 A cm^(-2) of current density and remains stable for 280 h,demonstrating significant potential for practical applications.Spherical aberration corrected scanning transmission electron microscopy(AC-STEM),X-ray absorption(XAS),and geometric phase analysis(GPA) indicate that the introduction of trace amounts of Pt SAs induces tensile strain in the Ni lattice,thereby altering the local electronic structure and coordination environment around cubic Ni for enhancing the water decomposition kinetics and fundamentally changing the reaction pathway.The doping-strain strategy showcases conformational relationships that could offer new ideas to construct efficient hydrogen evolution reaction(HER) electrocatalysts for industrial hydrogen production in the future.展开更多
Supported Pd catalyst is an important noble metal material in recent years due to its high catalytic performance in CO_(2)hydrogenation.A fluidized-bed plasma assisted atomic layer deposition(FP-ALD) process is report...Supported Pd catalyst is an important noble metal material in recent years due to its high catalytic performance in CO_(2)hydrogenation.A fluidized-bed plasma assisted atomic layer deposition(FP-ALD) process is reported to fabricate Pd nanoparticle catalyst over γ-Al_(2)O_(3)or Fe_(2)O_(3)/γ-Al_(2)O_(3)support,using palladium hexafluoroacetylacetonate as the Pd precursor and H_(2)plasma as counter-reactant.Scanning transmission electron microscopy exhibits that highdensity Pd nanoparticles are uniformly dispersed over Fe_(2)O_(3)/γ-Al_(2)O_(3)support with an average diameter of 4.4 nm.The deposited Pd-Fe_(2)O_(3)/γ-Al_(2)O_(3)shows excellent catalytic performance for CO_(2)hydrogenation in a dielectric barrier discharge reactor.Under a typical condition of H_(2)to CO_(2)ratio of 4 in the feed gas,the discharge power of 19.6 W,and gas hourly space velocity of10000 h^(-1),the conversion of CO_(2)is as high as 16.3% with CH_(3)OH and CH4selectivities of 26.5%and 3.9%,respectively.展开更多
The alkaline hydrogen evolution reaction(HER) on Pt-based catalysts is largely limited by the slow water dissociation kinetics. Pt-based single atom alloy catalysts(SAAC) with water dissociation sites have been demons...The alkaline hydrogen evolution reaction(HER) on Pt-based catalysts is largely limited by the slow water dissociation kinetics. Pt-based single atom alloy catalysts(SAAC) with water dissociation sites have been demonstrated as excellent alkaline HER catalysts. However, the regulation of their activity and stability at the atomic scale is still a great challenge. Herein, the kinetic and stability issues are successfully resolved via engineering the electronic structure of Pt-Co SAAC by Au-induced tensile strain. The atomic dispersion of Co into the Pt shell was confirmed by extended X-ray absorption fine structure and the electronic structure and catalytic HER performance was modulated by the tensile strain induced by the Pt shell thickness. An inverse volcano-type relation between HER activity and surface strain was found.Density functional theory(DFT) calculations reveal that the Au-induced tensile strain on Pt-Co shell can not only boost the adsorption and dissociation kinetics of water at Co site by upshifting the dband and promoting the electron transfer, but also downshift the d-band center of Pt in Pt-Co shell, leading to optimized H* adsorption/desorption. The champion catalyst provides an overpotential of only 14 m V at the current density of 10 mA cm^(-2). This work not only provides an effective strategy for the construction of single-atom alloy electrocatalysts for high performance toward alkaline HER but also sheds light on the understanding of the reaction mechanism at the atomic level.展开更多
Hydrogen generation from electrochemical water splitting powered by renewable energy is important to the sustainable society,but the prohibitive cost of current Pt electrocatalyst has impeded the large-scale productio...Hydrogen generation from electrochemical water splitting powered by renewable energy is important to the sustainable society,but the prohibitive cost of current Pt electrocatalyst has impeded the large-scale production of hydrogen by water electrolysis.In this contribution,a new low-Pt electrocatalyst for hydrogen evolution reaction(HER) has been fabricated by a facile one-pot synthesis approach,in which Pt^(2+)cations and phosphomolybdic acid confined in the metal-organic frameworks(MOFs) were submitted to pyrolysis to yield Pt single atoms dispersed into Mo_(2)C nanocrystals in 3 D porous carbon matrix.The as-synthesized Pt_(1)-Mo_(2)C-C catalyst with Pt content of only 0.7 wt% exhibited remarkably enhanced activity for HER in 1 M KOH,with overpotential at 10 mA/cm^(2) lowered from 211 mV to 155 mV and 7-fold higher mass activity(7.14 A/mgpt) than the benchmark 20 wt% Pt/C.The promoted activity can be attributed to the electronic interaction between Pt single atoms and Mo2C surface,which not only improved water activation but also strengthened hydrogen adsorption,as indicated by FTIR and microcalorimetric characterizations.展开更多
Development of highly active and stable non-noble electrocatalysts with well-defined nanostructures is crucial for efficient hydrogen evolution reaction(HER). Herein, a novel three-dimensional(3D) selfsupported electr...Development of highly active and stable non-noble electrocatalysts with well-defined nanostructures is crucial for efficient hydrogen evolution reaction(HER). Herein, a novel three-dimensional(3D) selfsupported electrode consists of vanadium nitride(VN) nanodots and Co nanoparticles co-embedded and highly active single Co atoms anchored in N-doped carbon nanotubes supported on carbon cloth(VN-Co@CoSAs-NCNTs/CC) is fabricated via a one-step in situ nanoconfined pyrolysis strategy, which shows remarkable enhanced HER electrocatalytic activity in acidic medium. During pyrolysis, the formed VN nanodots induce the generation of atomic Co Nxsites in NCNTs, contributing to superior electrocatalytic activity. Experimental and density functional theory(DFT) calculation results reveal that the electrode has multiple accessible active sites, fast reaction kinetics, low charge/mass transfer resistances,high conductivity, as well as downshifted d-band center with a thermodynamically favorable hydrogen adsorption free energy(△G_(H·)), all of which greatly boost the HER performance. As a result, the VNCo@CoSAs-NCNTs/CC electrode displays superb catalytic performance toward HER with a low overpotential of 29 mV at 10 mA cm^(-2) in acidic medium, which could maintain for at least 60 h of stable performance. This work opens a facile avenue to explore low-cost, high performance, but inexpensive metals/nitrogen-doped carbon composite electrocatalysts for HER.展开更多
Hydrogen evolution reaction(HER) is crucial for achieving sustainable development and carbon neutrality, and thus demands efficient catalysts, which necessitates fundamental theory to relieve trial-and-error experimen...Hydrogen evolution reaction(HER) is crucial for achieving sustainable development and carbon neutrality, and thus demands efficient catalysts, which necessitates fundamental theory to relieve trial-and-error experiment. To fast screen HER candidates, most studies focus on d-band center(ε)associated with the Gibbs energy of H* adsorption(ΔG). Unfortunately, εrule is not applicable to Pt single atoms on transition metal disulfides(Pt_(1)/TMDs) because of the additional contributions from p states of S atom. Here, we propose a new HER descriptor — d-band frontier(d) by defining the weight of d-band in the energy range of [-1.0 eV, 1.0 eV] of Pt single atoms. This dis exactly correlated with the ΔGof Pt_(1)/TMDs, and thus perfectly describes the structure–activity relationship, as validated by systematical experimental evidences. Moreover, this ddescriptor can be extended to Pt single atoms anchored on other supports(e.g., CN, C, MoO, and CoO), indicating its promising generality.展开更多
Hydrogen,a renewable and outstanding energy carrier with zero carbon dioxide emission,is regarded as the best alternative to fossil fuels.The most preferred route to large-scale production of hydrogen is by water elec...Hydrogen,a renewable and outstanding energy carrier with zero carbon dioxide emission,is regarded as the best alternative to fossil fuels.The most preferred route to large-scale production of hydrogen is by water electrolysis from the intermittent sources(e.g.,wind,solar,hydro,and tidal energy).However,the efficiency of water electrolysis is very much dependent on the activity of electrocatalysts.Thus,designing high-effective,stable,and cheap materials for hydrogen evolution reaction(HER)could have a substantial impact on renewable energy technologies.Recently,single-atom catalysts(SACs)have emerged as a new frontier in catalysis science,because SACs have maximum atom-utilization efficiency and excellent catalytic reaction activity.Various synthesis methods and analytical techniques have been adopted to prepare and characterize these SACs.In this review,we discuss recent progress on SACs synthesis,characterization methods,and their catalytic applications.Particularly,we highlight their unique electrochemical characteristics toward HER.Finally,the current key challenges in SACs for HER are pointed out and some potential directions are proposed as well.展开更多
Development of high-performance and cost-effective catalysts for electrocatalytic hydrogen evolution reaction(HER)play crucial role in the growing hydrogen economy.Recently,the atomically dispersed metal catalysts hav...Development of high-performance and cost-effective catalysts for electrocatalytic hydrogen evolution reaction(HER)play crucial role in the growing hydrogen economy.Recently,the atomically dispersed metal catalysts have attracted increasing attention due to their ultimate atom utilization and great potential for highly cost-effective and high-efficiency HER electrocatalyst.Herein,we propose a hightemperature treatment strategy to furtherly improve the HER performance of atomically dispersed Ptbased catalyst.Interestingly,after appropriate high-temperature treatment on the atomically dispersed Pt0.8@CN,the Pt species on the designed N-doped porous carbon substrate with rich defect sites can be re-dispersed to single atom state with new coordination environment.The obtained Pt0.8@CN-1000 shows superior HER performance with overpotential of 13 m V at 10 m A cm^(-2)and mass activity of 11,284 m A/mgPtat-0.1 V,much higher than that of the pristine Pt0.8@CN and commercial Pt/C catalyst.The experimental and theoretical investigations indicate that the high-temperature treatment induces the restructuring of coordination environment and then the optimized Pt electronic state leads to the enhanced HER performances.This work affords new strategy and insights to develop the atomically dispersed high-efficiency catalysts.展开更多
The B-spline basis set plus complex scaling method is applied to the numerical calculation of the exact resonance parameters Er and Г/2 of a hydrogen atom in parallel electric and magnetic fields. The method can calc...The B-spline basis set plus complex scaling method is applied to the numerical calculation of the exact resonance parameters Er and Г/2 of a hydrogen atom in parallel electric and magnetic fields. The method can calculate the ground and higher excited resonances accurately and efficiently. The resonance parameters with accuracies of 10^-9 - 10^-12 for hydrogen atom in parallel fields with different field strengths and symmetries are presented and compared with previous ones. Extension to the calculation of Rydberg atom in crossed electric and magnetic fields and of atomic double excited states in external electric fields is discussed.展开更多
The interaction between intense femtosecond laser pulses and hydrogen atomic clusters is studied by a simplified Coulomb explosion model. The dependences of average proton kinetic energy on cluster size, pulse duratio...The interaction between intense femtosecond laser pulses and hydrogen atomic clusters is studied by a simplified Coulomb explosion model. The dependences of average proton kinetic energy on cluster size, pulse duration, laser intensity and wavelength are studied respectively. The calculated results indicate that the irradiation of a femtosecond laser of longer wavelength on hydrogen atomic clusters may be a simple, economical way to produce highly kinetic hydrogen ions. The phenomenon suggests that the irradiation of femtosecond laser of longer wavelength on deuterium atomic clusters may be easier than that of shorter wavelength to drive nuclear fusion reactions. The product of the laser intensity and the squared laser wavelength needed to make proton energy saturated as a function of the squared cluster radius is also investigated. The proton energy distribution calculated is also shown and compared with the experimental data. Our results are in agreement with the experimental results fairly well.展开更多
Urea oxidation reaction(UOR) has been selected as substitution for oxygen evolution reaction ascribing to its low thermodynamic voltage as well as utilization of nickel as electrocatalyst.Herein,we report the formatio...Urea oxidation reaction(UOR) has been selected as substitution for oxygen evolution reaction ascribing to its low thermodynamic voltage as well as utilization of nickel as electrocatalyst.Herein,we report the formation of nickel single atoms(Ni-SAs) as exceptional bifunctional electrocatalyst toward UOR and hydrogen evolution reaction(HER) in urea-assisted water splitting.In UOR catalysis,Ni-SAs perform a superior catalytic performance than Ni-NP/NC and Pt/C ascribing to the formation of HOO-Ni-N_(4) structure evidenced by in-situ Raman spectroscopy,corresponding to a boosted mass activity by 175-fold at 1.4 V vs.RHE than Ni-NP/NC.Furthermore,Ni-SAs requires only 450 mV overpotential to obtain HER current density of 500 mA cm^(-2).136 mA cm^(-2) is achieved in urea-assisted water splitting at1.7 V for Ni-SAs,boosted by 5.7 times than Pt/C-IrO_(2) driven water splitting.展开更多
The Tianjin University has developed a molybdenum carbide supported monoatomic catalyst for acetylene hydrogenation.Among these metal components,monoatomic nickel,monoatomic cobalt or monoatomic copper can form Ni-Mo,...The Tianjin University has developed a molybdenum carbide supported monoatomic catalyst for acetylene hydrogenation.Among these metal components,monoatomic nickel,monoatomic cobalt or monoatomic copper can form Ni-Mo,Ni-Co,and Ni-Cu bonds with molybdenum atoms in MoC,which can enhance the adsorption and activation of hydrogen molecules to improve the hydrogenation activity.展开更多
The dynamic dipole polarizabilities for 1S, 2S and 3S states of the hydrogen atom are calculated using the finite B-spline basis set method, and the magic wavelengths for 1S-2S and 1S-3S transitions are identified. In...The dynamic dipole polarizabilities for 1S, 2S and 3S states of the hydrogen atom are calculated using the finite B-spline basis set method, and the magic wavelengths for 1S-2S and 1S-3S transitions are identified. In comparison of the solutions from the Schr6dinger and Dirac equations, the relativistic corrections on the magic wavelengths are of the order of 10-2 nm. The laser intensities for a 300-Er-deep optical trap and the heating rates at 514 and 1371 nm are estimated. The reliable prediction of the magic wavelengths would be helpful for the experimental design on the optical trapping of the hydrogen atoms, and in turn, it would be helpful to improve the accuracy of the measurements of the hydrogen 1S-2S and 1S-3S transitions.展开更多
We discuss the equivalent form of the Ldvy-Leblond equation such that the nilpotent matrices are two-dimensional. We show that this equation can be obtained in the non-relativistic limit of the （2＋1）-dimensional Di...We discuss the equivalent form of the Ldvy-Leblond equation such that the nilpotent matrices are two-dimensional. We show that this equation can be obtained in the non-relativistic limit of the （2＋1）-dimensional Dirac equation. Phrthermore, we analyze the case with four-dimensional matrices, propose a Hamiltonian for the equation in （3＋1） dimensions, and solve it for a Coulomb potential The quantized energy levels for the hydrogen atom are obtained, and the result is consistent with the non-relativistic quantum mechanics.展开更多
Exploration of cost-effective Pt/C catalysts has been a significant issue for electrochemical hydrogen evolution reaction(HER) toward sustainable energy conversion and storage.Herein,we report a fabrication strategy b...Exploration of cost-effective Pt/C catalysts has been a significant issue for electrochemical hydrogen evolution reaction(HER) toward sustainable energy conversion and storage.Herein,we report a fabrication strategy by employing platelet carbon nanofibers(p-CNF) as the support to immobilize Pt-CoO HER electrocatalyst using atomic layer deposition method.The edge-rich p-CNF support is found to act as the anchoring sites of Pt nanoparticles and favorably capture electrons from Pt to yield electron-deficient Pt surfaces for the boosted HER.Additionally,the sequential growth of CoO onto the Pt/p-CNF catalyst elaborately constructs the Pt-CoO interface and facilitates the electron transfer from Pt to CoO,which further enhances the HER activity.These advantages endow the fabricated Pt-CoO/p-CNF catalyst with the superior HER activity,e.g.,a very low overpotential of 26 mV at the current density of 10 mA·cm-2 and a mass activity of 4.42 A·mgPt-1at the overpotential of 30 mV,18.8 times higher than that of the commercial20 wt% Pt/C catalyst.The insights reported here could shed light on for the fabrication of cost-effective Pt-based composite HER catalysts.展开更多
文摘In this paper, two recurrence formulas for radial average values of N-dimensional hydrogen atom are derived. Explicit expressions for <n rJ N-2 |r s|n rJ N-2 > are given for 3≥s≥-6. These results can be applied to discuss average value of centrifugal potential energy and other physical quantities. The relevant results of the usual hydrogen atom are contained in more general conclusion of this paper as special cases.
文摘In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix elements are also derived.
基金supported by National Natural Science Foundation of China(52373221,U1910208,52250119)the National Key R&D Program of China(2020YFA0710403)the Scientific Research Fund of Hunan Provincial Education Department(NO.23B0114).
文摘Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and selectivity.However,most of the reported SA catalysts are fixed through the strong bonding between the dispersed single metallic atoms with nonmetallic atoms of the substrates,which greatly limits the controllable regulation of electrocatalytic activity of SA catalysts.In this work,Pt-Ni bonded Pt SA catalyst with adjustable electronic states was successfully constructed through a controllable electrochemical reduction on the coordination unsaturated amorphous Ni(OH)_(2)nanosheet arrays.Based on the X-ray absorption fine structure analysis and first-principles calculations,Pt SA was bonded with Ni sites of amorphous Ni(OH)_(2),rather than conventional O sites,resulting in negatively charged Pt^(δ-).In situ Raman spectroscopy revealed that the changed configuration and electronic states greatly enhanced absorbability for activated hydrogen atoms,which were the essential intermediate for alkaline hydrogen evolution reaction.The hydrogen spillover process was revealed from amorphous Ni(OH)_(2)that effectively cleave the H-O-H bond of H_(2)O and produce H atom to the Pt SA sites,leading to a low overpotential of 48 mV in alkaline electrolyte at-1000 mA cm^(-2)mg^(-1)_(Pt),evidently better than commercial Pt/C catalysts.This work provided new strategy for the control-lable modulation of the local structure of SA catalysts and the systematic regulation of the electronic states.
基金National Natural Science Foundation of China (grants U22A20418, 22075196, and 21878204)Research Project Supported by Shanxi Scholarship Council of China (2022-050)。
文摘Strategically designing the electrocatalytic system and cleverly inducing strain is an effective approach to balance the cost and activity of Pt-based electrocatalysts for industrial-scale hydrogen production.Herein,we present a unipolar pulsed electrodeposition(UPED) strategy to induce strain in the Ni lattice by introducing trace amounts of Pt single atoms(SAs)(0.22 wt%).The overpotential decreased by 183 mV at 10 mA cm^(-2) in 1.0 M KOH after introducing trace amounts of Pt_(SAs).The industrial electrolyzer,assembled with Pt_(SAs)Ni cathode and a commercial NiFeO_(x) anode,requires a cell voltage of 1.90 V to attain 1 A cm^(-2) of current density and remains stable for 280 h,demonstrating significant potential for practical applications.Spherical aberration corrected scanning transmission electron microscopy(AC-STEM),X-ray absorption(XAS),and geometric phase analysis(GPA) indicate that the introduction of trace amounts of Pt SAs induces tensile strain in the Ni lattice,thereby altering the local electronic structure and coordination environment around cubic Ni for enhancing the water decomposition kinetics and fundamentally changing the reaction pathway.The doping-strain strategy showcases conformational relationships that could offer new ideas to construct efficient hydrogen evolution reaction(HER) electrocatalysts for industrial hydrogen production in the future.
基金financially supported by National Natural Science Foundation of China (Nos. 12075032 and 12105021)Beijing Municipal Natural Science Foundation (Nos.8222055 and 2232061)+1 种基金Yunnan Police College Project (No. YJKF002)Beijing Institute of Graphic Communication Project (No. Ec202207)。
文摘Supported Pd catalyst is an important noble metal material in recent years due to its high catalytic performance in CO_(2)hydrogenation.A fluidized-bed plasma assisted atomic layer deposition(FP-ALD) process is reported to fabricate Pd nanoparticle catalyst over γ-Al_(2)O_(3)or Fe_(2)O_(3)/γ-Al_(2)O_(3)support,using palladium hexafluoroacetylacetonate as the Pd precursor and H_(2)plasma as counter-reactant.Scanning transmission electron microscopy exhibits that highdensity Pd nanoparticles are uniformly dispersed over Fe_(2)O_(3)/γ-Al_(2)O_(3)support with an average diameter of 4.4 nm.The deposited Pd-Fe_(2)O_(3)/γ-Al_(2)O_(3)shows excellent catalytic performance for CO_(2)hydrogenation in a dielectric barrier discharge reactor.Under a typical condition of H_(2)to CO_(2)ratio of 4 in the feed gas,the discharge power of 19.6 W,and gas hourly space velocity of10000 h^(-1),the conversion of CO_(2)is as high as 16.3% with CH_(3)OH and CH4selectivities of 26.5%and 3.9%,respectively.
基金supported by the National Natural Science Foundation of China (U2032151)the National Key R&D Program of China (2018YFB1502600)+1 种基金the Basic Research and Applied Basic Research Foundation of Guangzhou (B3210580)the Natural Science Foundation of Guangdong Province (B6211050)。
文摘The alkaline hydrogen evolution reaction(HER) on Pt-based catalysts is largely limited by the slow water dissociation kinetics. Pt-based single atom alloy catalysts(SAAC) with water dissociation sites have been demonstrated as excellent alkaline HER catalysts. However, the regulation of their activity and stability at the atomic scale is still a great challenge. Herein, the kinetic and stability issues are successfully resolved via engineering the electronic structure of Pt-Co SAAC by Au-induced tensile strain. The atomic dispersion of Co into the Pt shell was confirmed by extended X-ray absorption fine structure and the electronic structure and catalytic HER performance was modulated by the tensile strain induced by the Pt shell thickness. An inverse volcano-type relation between HER activity and surface strain was found.Density functional theory(DFT) calculations reveal that the Au-induced tensile strain on Pt-Co shell can not only boost the adsorption and dissociation kinetics of water at Co site by upshifting the dband and promoting the electron transfer, but also downshift the d-band center of Pt in Pt-Co shell, leading to optimized H* adsorption/desorption. The champion catalyst provides an overpotential of only 14 m V at the current density of 10 mA cm^(-2). This work not only provides an effective strategy for the construction of single-atom alloy electrocatalysts for high performance toward alkaline HER but also sheds light on the understanding of the reaction mechanism at the atomic level.
基金supports from the National Natural Science Foundation of China(21690080,21690084,21673228,21721004,and 21878289)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB17020100)。
文摘Hydrogen generation from electrochemical water splitting powered by renewable energy is important to the sustainable society,but the prohibitive cost of current Pt electrocatalyst has impeded the large-scale production of hydrogen by water electrolysis.In this contribution,a new low-Pt electrocatalyst for hydrogen evolution reaction(HER) has been fabricated by a facile one-pot synthesis approach,in which Pt^(2+)cations and phosphomolybdic acid confined in the metal-organic frameworks(MOFs) were submitted to pyrolysis to yield Pt single atoms dispersed into Mo_(2)C nanocrystals in 3 D porous carbon matrix.The as-synthesized Pt_(1)-Mo_(2)C-C catalyst with Pt content of only 0.7 wt% exhibited remarkably enhanced activity for HER in 1 M KOH,with overpotential at 10 mA/cm^(2) lowered from 211 mV to 155 mV and 7-fold higher mass activity(7.14 A/mgpt) than the benchmark 20 wt% Pt/C.The promoted activity can be attributed to the electronic interaction between Pt single atoms and Mo2C surface,which not only improved water activation but also strengthened hydrogen adsorption,as indicated by FTIR and microcalorimetric characterizations.
基金supported by grants from the National Natural Science Foundation of China (21971129, 21961022, 21661023,21802076, and 21962013)the 111 Project (D20033)+2 种基金the Natural Science Foundation of Inner Mongolia Autonomous Region of China (2018BS05007)the Program of Higher-level Talents of IMU (21300-5195109)the Cooperation Project of State Key Laboratory of Baiyun Obo Rare Earth Resource Researches and Comprehensive Utilization (2017Z1950)。
文摘Development of highly active and stable non-noble electrocatalysts with well-defined nanostructures is crucial for efficient hydrogen evolution reaction(HER). Herein, a novel three-dimensional(3D) selfsupported electrode consists of vanadium nitride(VN) nanodots and Co nanoparticles co-embedded and highly active single Co atoms anchored in N-doped carbon nanotubes supported on carbon cloth(VN-Co@CoSAs-NCNTs/CC) is fabricated via a one-step in situ nanoconfined pyrolysis strategy, which shows remarkable enhanced HER electrocatalytic activity in acidic medium. During pyrolysis, the formed VN nanodots induce the generation of atomic Co Nxsites in NCNTs, contributing to superior electrocatalytic activity. Experimental and density functional theory(DFT) calculation results reveal that the electrode has multiple accessible active sites, fast reaction kinetics, low charge/mass transfer resistances,high conductivity, as well as downshifted d-band center with a thermodynamically favorable hydrogen adsorption free energy(△G_(H·)), all of which greatly boost the HER performance. As a result, the VNCo@CoSAs-NCNTs/CC electrode displays superb catalytic performance toward HER with a low overpotential of 29 mV at 10 mA cm^(-2) in acidic medium, which could maintain for at least 60 h of stable performance. This work opens a facile avenue to explore low-cost, high performance, but inexpensive metals/nitrogen-doped carbon composite electrocatalysts for HER.
基金supported by the National Natural Science Foundation of China(21872061,22102100)an the National Key Research and Development Program of China(2018YFC1800801)。
文摘Hydrogen evolution reaction(HER) is crucial for achieving sustainable development and carbon neutrality, and thus demands efficient catalysts, which necessitates fundamental theory to relieve trial-and-error experiment. To fast screen HER candidates, most studies focus on d-band center(ε)associated with the Gibbs energy of H* adsorption(ΔG). Unfortunately, εrule is not applicable to Pt single atoms on transition metal disulfides(Pt_(1)/TMDs) because of the additional contributions from p states of S atom. Here, we propose a new HER descriptor — d-band frontier(d) by defining the weight of d-band in the energy range of [-1.0 eV, 1.0 eV] of Pt single atoms. This dis exactly correlated with the ΔGof Pt_(1)/TMDs, and thus perfectly describes the structure–activity relationship, as validated by systematical experimental evidences. Moreover, this ddescriptor can be extended to Pt single atoms anchored on other supports(e.g., CN, C, MoO, and CoO), indicating its promising generality.
基金financially supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)Institut National de la Recherche Scientifique(INRS)the National Natural Science Foundation of China(516722040)
文摘Hydrogen,a renewable and outstanding energy carrier with zero carbon dioxide emission,is regarded as the best alternative to fossil fuels.The most preferred route to large-scale production of hydrogen is by water electrolysis from the intermittent sources(e.g.,wind,solar,hydro,and tidal energy).However,the efficiency of water electrolysis is very much dependent on the activity of electrocatalysts.Thus,designing high-effective,stable,and cheap materials for hydrogen evolution reaction(HER)could have a substantial impact on renewable energy technologies.Recently,single-atom catalysts(SACs)have emerged as a new frontier in catalysis science,because SACs have maximum atom-utilization efficiency and excellent catalytic reaction activity.Various synthesis methods and analytical techniques have been adopted to prepare and characterize these SACs.In this review,we discuss recent progress on SACs synthesis,characterization methods,and their catalytic applications.Particularly,we highlight their unique electrochemical characteristics toward HER.Finally,the current key challenges in SACs for HER are pointed out and some potential directions are proposed as well.
基金financially supported by the National Science Foundation of China(21773112,21173119,and 21273109)the National Key Technology R&D Program of China(2017YFB0310704)the Fundamental Research Funds for the Central Universities and the Hubei Key Laboratory for Processing and Application of Catalytic Materials(CH201401)。
文摘Development of high-performance and cost-effective catalysts for electrocatalytic hydrogen evolution reaction(HER)play crucial role in the growing hydrogen economy.Recently,the atomically dispersed metal catalysts have attracted increasing attention due to their ultimate atom utilization and great potential for highly cost-effective and high-efficiency HER electrocatalyst.Herein,we propose a hightemperature treatment strategy to furtherly improve the HER performance of atomically dispersed Ptbased catalyst.Interestingly,after appropriate high-temperature treatment on the atomically dispersed Pt0.8@CN,the Pt species on the designed N-doped porous carbon substrate with rich defect sites can be re-dispersed to single atom state with new coordination environment.The obtained Pt0.8@CN-1000 shows superior HER performance with overpotential of 13 m V at 10 m A cm^(-2)and mass activity of 11,284 m A/mgPtat-0.1 V,much higher than that of the pristine Pt0.8@CN and commercial Pt/C catalyst.The experimental and theoretical investigations indicate that the high-temperature treatment induces the restructuring of coordination environment and then the optimized Pt electronic state leads to the enhanced HER performances.This work affords new strategy and insights to develop the atomically dispersed high-efficiency catalysts.
基金Project supported by the National Natural Science Foundation of China (Grant No 10674154)
文摘The B-spline basis set plus complex scaling method is applied to the numerical calculation of the exact resonance parameters Er and Г/2 of a hydrogen atom in parallel electric and magnetic fields. The method can calculate the ground and higher excited resonances accurately and efficiently. The resonance parameters with accuracies of 10^-9 - 10^-12 for hydrogen atom in parallel fields with different field strengths and symmetries are presented and compared with previous ones. Extension to the calculation of Rydberg atom in crossed electric and magnetic fields and of atomic double excited states in external electric fields is discussed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10575046 and 10775062)
文摘The interaction between intense femtosecond laser pulses and hydrogen atomic clusters is studied by a simplified Coulomb explosion model. The dependences of average proton kinetic energy on cluster size, pulse duration, laser intensity and wavelength are studied respectively. The calculated results indicate that the irradiation of a femtosecond laser of longer wavelength on hydrogen atomic clusters may be a simple, economical way to produce highly kinetic hydrogen ions. The phenomenon suggests that the irradiation of femtosecond laser of longer wavelength on deuterium atomic clusters may be easier than that of shorter wavelength to drive nuclear fusion reactions. The product of the laser intensity and the squared laser wavelength needed to make proton energy saturated as a function of the squared cluster radius is also investigated. The proton energy distribution calculated is also shown and compared with the experimental data. Our results are in agreement with the experimental results fairly well.
基金supported by the National Natural Science Foundation of China(No.22209126)。
文摘Urea oxidation reaction(UOR) has been selected as substitution for oxygen evolution reaction ascribing to its low thermodynamic voltage as well as utilization of nickel as electrocatalyst.Herein,we report the formation of nickel single atoms(Ni-SAs) as exceptional bifunctional electrocatalyst toward UOR and hydrogen evolution reaction(HER) in urea-assisted water splitting.In UOR catalysis,Ni-SAs perform a superior catalytic performance than Ni-NP/NC and Pt/C ascribing to the formation of HOO-Ni-N_(4) structure evidenced by in-situ Raman spectroscopy,corresponding to a boosted mass activity by 175-fold at 1.4 V vs.RHE than Ni-NP/NC.Furthermore,Ni-SAs requires only 450 mV overpotential to obtain HER current density of 500 mA cm^(-2).136 mA cm^(-2) is achieved in urea-assisted water splitting at1.7 V for Ni-SAs,boosted by 5.7 times than Pt/C-IrO_(2) driven water splitting.
文摘The Tianjin University has developed a molybdenum carbide supported monoatomic catalyst for acetylene hydrogenation.Among these metal components,monoatomic nickel,monoatomic cobalt or monoatomic copper can form Ni-Mo,Ni-Co,and Ni-Cu bonds with molybdenum atoms in MoC,which can enhance the adsorption and activation of hydrogen molecules to improve the hydrogenation activity.
基金Supported by the National Basic Research Program of China under Grant No 2012CB821305the National Natural Science Foundation of China under Grant No 91536102
文摘The dynamic dipole polarizabilities for 1S, 2S and 3S states of the hydrogen atom are calculated using the finite B-spline basis set method, and the magic wavelengths for 1S-2S and 1S-3S transitions are identified. In comparison of the solutions from the Schr6dinger and Dirac equations, the relativistic corrections on the magic wavelengths are of the order of 10-2 nm. The laser intensities for a 300-Er-deep optical trap and the heating rates at 514 and 1371 nm are estimated. The reliable prediction of the magic wavelengths would be helpful for the experimental design on the optical trapping of the hydrogen atoms, and in turn, it would be helpful to improve the accuracy of the measurements of the hydrogen 1S-2S and 1S-3S transitions.
文摘We discuss the equivalent form of the Ldvy-Leblond equation such that the nilpotent matrices are two-dimensional. We show that this equation can be obtained in the non-relativistic limit of the （2＋1）-dimensional Dirac equation. Phrthermore, we analyze the case with four-dimensional matrices, propose a Hamiltonian for the equation in （3＋1） dimensions, and solve it for a Coulomb potential The quantized energy levels for the hydrogen atom are obtained, and the result is consistent with the non-relativistic quantum mechanics.
基金financially supported by the National Natural Science Foundation of China (21922803 and 21776077)the Shanghai Natural Science Foundation (17ZR1407300 and 17ZR1407500)+3 种基金the Program for the Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learningthe Shanghai Rising-Star Program (17QA1401200)the State Key Laboratory of Organic-Inorganic Composites (oic-201801007)the Open Project of State Key Laboratory of Chemical Engineering (SKLChe15C03)。
文摘Exploration of cost-effective Pt/C catalysts has been a significant issue for electrochemical hydrogen evolution reaction(HER) toward sustainable energy conversion and storage.Herein,we report a fabrication strategy by employing platelet carbon nanofibers(p-CNF) as the support to immobilize Pt-CoO HER electrocatalyst using atomic layer deposition method.The edge-rich p-CNF support is found to act as the anchoring sites of Pt nanoparticles and favorably capture electrons from Pt to yield electron-deficient Pt surfaces for the boosted HER.Additionally,the sequential growth of CoO onto the Pt/p-CNF catalyst elaborately constructs the Pt-CoO interface and facilitates the electron transfer from Pt to CoO,which further enhances the HER activity.These advantages endow the fabricated Pt-CoO/p-CNF catalyst with the superior HER activity,e.g.,a very low overpotential of 26 mV at the current density of 10 mA·cm-2 and a mass activity of 4.42 A·mgPt-1at the overpotential of 30 mV,18.8 times higher than that of the commercial20 wt% Pt/C catalyst.The insights reported here could shed light on for the fabrication of cost-effective Pt-based composite HER catalysts.
