Disrupting the symmetric electron distribution of porphyrin-like Fe singleatom catalysts has been considered as an effective way to harvest high intrinsic activity.Understanding the catalytic performance governed by g...Disrupting the symmetric electron distribution of porphyrin-like Fe singleatom catalysts has been considered as an effective way to harvest high intrinsic activity.Understanding the catalytic performance governed by geometric microstrains is highly desirable for further optimization of such efficient sites.Here,we decipher the crucial role of local microstrain in boosting intrinsic activity and durability of asymmetric Fe single-atom catalysts(Fe-N_(3)S_(1))by replacing one N atom with S atom.The high-curvature hollow carbon nanosphere substrate introduces 1.3%local compressive strain to Fe-N bonds and 1.5%tensile strain to Fe-S bonds,downshifting the d-band center and accelerating the kinetics of*OH reduction.Consequently,highly curved Fe-N_(3)S_(1)sites anchored on hollow carbon nanosphere(FeNS-HNS-20)exhibit negligible current loss,a high half-wave potential of 0.922 V vs.RHE and turnover frequency of 6.2 e^(−1)s^(−1)site−1,which are 53 mV more positive and 1.7 times that of flat Fe-N-S counterpart,respectively.More importantly,multiple operando spectroscopies monitored the dynamic optimization of strained Fe-N_(3)S_(1)sites into Fe-N_(3)sites,further mitigating the overadsorption of*OH intermediates.This work not only sheds new light on local microstrain-induced catalytic enhancement,but also provides a plausible direction for optimizing efficient asymmetric sites via geometric configurations.展开更多
According to the stress-strain curves of single-phase martensite and single-phase ferrite steels,whose compositions are similar to those of martensite and ferrite in low Si-Mn-Nb dual-phase steel,the stress-strain cur...According to the stress-strain curves of single-phase martensite and single-phase ferrite steels,whose compositions are similar to those of martensite and ferrite in low Si-Mn-Nb dual-phase steel,the stress-strain curve of the low Si-Mn-Nb dual-phase steel was simulated using the finite element method（FEM）.The simulated result was compared with the measured one and they fit closely with each other, which proves that the FE model is correct.Based on the FE model,the microstress and microstrain of the dual-phase steel were analyzed. Meanwhile,the effective factors such as the volume fraction of martensite and the yield stress ratio between martensite and ferrite phases on the stress-strain curves of the dual-phase steel were simulated,too.The simulated results indicate that for the low Si-Mn-Nb dual-phase steel, the maximum stress occurs in the martensite region,while the maximum strain occurs in the ferrite one.The effect of the volume fraction of martensite（fm） and the yield stress ratio on the stress-strain curve of the dual-phase steel is small in the elastic part,while it is obvious in the plastic part.In the plastic part of this curve,the strain decreases with the increase of f_M,while it decreases with the decrease of the yield stress ratio.展开更多
The microstraining prior to yield of several common metallic materials has been studied.The resistances of metals to microstrain and to macroyield are believed to be based on different deformation mechanisms and to be...The microstraining prior to yield of several common metallic materials has been studied.The resistances of metals to microstrain and to macroyield are believed to be based on different deformation mechanisms and to be changed in different patterns.The influential factors upon the microstraining,such as heat treatment,prestrain,strain-aging and residual stress together with their mechanisms have been also discussed.展开更多
The elastic microstrains in a crystallite of electrodeposited nanocrystalline copper were investigated by analyzing the high resolution electron microscopy （HRTEM） image. The microstrain was considered as consisting...The elastic microstrains in a crystallite of electrodeposited nanocrystalline copper were investigated by analyzing the high resolution electron microscopy （HRTEM） image. The microstrain was considered as consisting of two parts, in which the uniform part was determined with fast Fourier transformation of the HRTEM image, while the non-uniform part of the microstrain in the crystallite was measured by means of peak finding. Atomic column spacing measurements show that the crystal lattice is contracted in the longitudinal direction, while expanded in the transverse direction of the elliptical crystallite, indicating that the variation of microstrain exists mainly near the grain boundary.展开更多
Alloying Pt with non-noble metals is effective for optimizing the activity of Pt-based electrocatalysts.However,the development of high-activity and stable hydrogen electrocatalysts remains challenging owing to the ra...Alloying Pt with non-noble metals is effective for optimizing the activity of Pt-based electrocatalysts.However,the development of high-activity and stable hydrogen electrocatalysts remains challenging owing to the random elemental distribution and weak interatomic bonding in alloys.Herein,we reported a Pt_(2)CoNi intermetallic nanocatalyst rich in surface microstrain for high-performance hydrogen electrocatalysis.The superlattice ordering crystalline structure ensures the specific positions of atoms in this nanocatalyst,resulting in the alternating arrangement of Pt and Co/Ni atoms.In one nanoparticle,multiple Pt_(2)CoNi grains are arranged along different grain orientations,which generates abundant surface microstrain due to the discrepancy of intermetallic lattice parameters.The unique crystal structure effectively modulates the electron distribution of Pt_(2)CoNi intermetallic nanocatalyst.The active sites of this nanocatalyst exhibit downshifted d-band centers,leading to accelerated hydrogen adsorption/desorption behavior.Resultantly,the Pt_(2)CoNi intermetallic nanocatalyst demonstrates impressive bifunctional hydrogen electrocatalytic capabilities for hydrogen evolution reaction(mass activity of 1.02 A/mg Pt and η_(10) variation of 3.7 mV after 10,000 cycles)and hydrogen oxidation reaction(kinetic mass activity of 4.08 A/mg Pt and 97.3%activity retention after 12 h operating at 0.1 V vs.RHE).This work provides a promising route for the development of efficient nanocatalysts with ingenious crystal structures.展开更多
The rock-salt cubic SnSe compound with multiple valleys and inherent low thermal conductivity is considered to be a promising thermoelectric compound.In this study,heterogeneous Pb atoms were strategically introduced ...The rock-salt cubic SnSe compound with multiple valleys and inherent low thermal conductivity is considered to be a promising thermoelectric compound.In this study,heterogeneous Pb atoms were strategically introduced into the lattice of cubic SnSe matrix,synergistically adjusting the thermoelectric transport properties of samples by optimizing hole carrier concentration(n)and suppressing thermal conductivity(κ_(tot)).When the doping content reached 0.08 mol,the peak power factor(PF)at 300 K increased to 20.00μW·cm^(-1)·K^(-2).The growing internal microstrain induced by the differences in atomic size strengthened the phonon scattering and effectively reduced the lattice thermal conductivity(κ_(L)).With further decoupling of the electrical and thermal transport properties,a peak thermoelectric figure of merit(ZT)of 0.82 and an average ZT of 0.42(300-750 K)were achieved in the samples doped with 0.10 mol Pb.These findings highlight the effectiveness of the selected dopants and demonstrate their synergy in improving the performance of thermoelectric materials.展开更多
All-inorganic perovskite solar cells(PSCs)have developed rapidly in the field of photovoltaics due to their excellent thermal and light stability.However,compared with organic–inorganic hybrid perovskites,the phase i...All-inorganic perovskite solar cells(PSCs)have developed rapidly in the field of photovoltaics due to their excellent thermal and light stability.However,compared with organic–inorganic hybrid perovskites,the phase instability of inorganic perovskite under humidity still remains as a critical issue that ham-pers the commercialization of inorganic PSCs.We originally propose in this work that microstrains between the perovskite lattices/grains play a key role in affecting the phase stability of inorganic perovskite.To this end,we inno-vatively design theπ-conjugated p-type molecule bis(2-ethylhexyl)3,30((4,8-bis(5-(2-ethylhexyl)-3,4-difluorothiophen-2-yl)benzo[1,2-b:4,5-b0]dithiophene-2,6-di yl)bis(3,300-dioctyl[2,20:50,200-terthiophene]-500,5-diyl))(2E,20 E)-bis(2-cyanoacrylate)(BTEC-2F)to covalent with the Pb dangling bonds in CsPbI2Br perovskite film,which significantly suppress the trap states and release the defect-induced local stress between perovskite grains.The interplay between the microstrains and phase stability of the inorganic perovskite are scrutinized by a series of charac-terizations including x-ray photoelectron spectroscopy,photoluminescence,x-ray diffraction,scanning electron microscopy,and so forth,based on which,we conclude that weaker local stresses in the perovskite film engender superior phase stability by preventing the perovskite lattice distortion under humidity.By this rational design,PSCs based on CsPbI2Br perovskite system deliver an outstanding power conversion efficiency(PCE)up to 16.25%.The unencapsulated device also exhibits an exceptional moisture stability by retaining over 80%of the initial PCE after 500 h aging in ambient with relative humidity of(RH)25%.展开更多
We demonstrate for the first time that a short time of microwave irradiation on the oxide precursor of a Cu/ZnO/Al2O3 catalyst can provide unique opportunity for tailoring the microstructure and activity of the cataly...We demonstrate for the first time that a short time of microwave irradiation on the oxide precursor of a Cu/ZnO/Al2O3 catalyst can provide unique opportunity for tailoring the microstructure and activity of the catalyst for methanol steam reforming. It is shown by in situ XRD that a considerable increase in the microstrain of Cu nanocrystals could be achieved in the catalysts processed by microwave irradiation for 310 min, which correlates well with the enhanced CH3OH conversion as observed on the corresponding samples. The present work also confirms that although the high specific surface area of Cu is a prerequisite for catalytic activity, it does not account for the observed changes in activity and selectivity alone without taking bulk microstructural changes into account.展开更多
基金supported by the Natural Science Foundation of Shandong Province (ZR2024JQ004)the National Natural Science Foundation of China (22108306, 22478432)Taishan Scholars Program of Shandong Province
文摘Disrupting the symmetric electron distribution of porphyrin-like Fe singleatom catalysts has been considered as an effective way to harvest high intrinsic activity.Understanding the catalytic performance governed by geometric microstrains is highly desirable for further optimization of such efficient sites.Here,we decipher the crucial role of local microstrain in boosting intrinsic activity and durability of asymmetric Fe single-atom catalysts(Fe-N_(3)S_(1))by replacing one N atom with S atom.The high-curvature hollow carbon nanosphere substrate introduces 1.3%local compressive strain to Fe-N bonds and 1.5%tensile strain to Fe-S bonds,downshifting the d-band center and accelerating the kinetics of*OH reduction.Consequently,highly curved Fe-N_(3)S_(1)sites anchored on hollow carbon nanosphere(FeNS-HNS-20)exhibit negligible current loss,a high half-wave potential of 0.922 V vs.RHE and turnover frequency of 6.2 e^(−1)s^(−1)site−1,which are 53 mV more positive and 1.7 times that of flat Fe-N-S counterpart,respectively.More importantly,multiple operando spectroscopies monitored the dynamic optimization of strained Fe-N_(3)S_(1)sites into Fe-N_(3)sites,further mitigating the overadsorption of*OH intermediates.This work not only sheds new light on local microstrain-induced catalytic enhancement,but also provides a plausible direction for optimizing efficient asymmetric sites via geometric configurations.
基金supported by the Natural Science Foundation of Hebei Province(No.E2008000822) the Program for One Hundred Excellent Talents of Hebei Province,China.
文摘According to the stress-strain curves of single-phase martensite and single-phase ferrite steels,whose compositions are similar to those of martensite and ferrite in low Si-Mn-Nb dual-phase steel,the stress-strain curve of the low Si-Mn-Nb dual-phase steel was simulated using the finite element method（FEM）.The simulated result was compared with the measured one and they fit closely with each other, which proves that the FE model is correct.Based on the FE model,the microstress and microstrain of the dual-phase steel were analyzed. Meanwhile,the effective factors such as the volume fraction of martensite and the yield stress ratio between martensite and ferrite phases on the stress-strain curves of the dual-phase steel were simulated,too.The simulated results indicate that for the low Si-Mn-Nb dual-phase steel, the maximum stress occurs in the martensite region,while the maximum strain occurs in the ferrite one.The effect of the volume fraction of martensite（fm） and the yield stress ratio on the stress-strain curve of the dual-phase steel is small in the elastic part,while it is obvious in the plastic part.In the plastic part of this curve,the strain decreases with the increase of f_M,while it decreases with the decrease of the yield stress ratio.
文摘The microstraining prior to yield of several common metallic materials has been studied.The resistances of metals to microstrain and to macroyield are believed to be based on different deformation mechanisms and to be changed in different patterns.The influential factors upon the microstraining,such as heat treatment,prestrain,strain-aging and residual stress together with their mechanisms have been also discussed.
基金Funded by the National Natural Science Foundation of China (No. 50171048)
文摘The elastic microstrains in a crystallite of electrodeposited nanocrystalline copper were investigated by analyzing the high resolution electron microscopy （HRTEM） image. The microstrain was considered as consisting of two parts, in which the uniform part was determined with fast Fourier transformation of the HRTEM image, while the non-uniform part of the microstrain in the crystallite was measured by means of peak finding. Atomic column spacing measurements show that the crystal lattice is contracted in the longitudinal direction, while expanded in the transverse direction of the elliptical crystallite, indicating that the variation of microstrain exists mainly near the grain boundary.
基金supported by the Natural Science Foundation of Tianjin(24JCZDJC01080)the National Natural Science Foundation of China(52372218)the National Key Research and Development Program of China(2025YFE0109500).
文摘Alloying Pt with non-noble metals is effective for optimizing the activity of Pt-based electrocatalysts.However,the development of high-activity and stable hydrogen electrocatalysts remains challenging owing to the random elemental distribution and weak interatomic bonding in alloys.Herein,we reported a Pt_(2)CoNi intermetallic nanocatalyst rich in surface microstrain for high-performance hydrogen electrocatalysis.The superlattice ordering crystalline structure ensures the specific positions of atoms in this nanocatalyst,resulting in the alternating arrangement of Pt and Co/Ni atoms.In one nanoparticle,multiple Pt_(2)CoNi grains are arranged along different grain orientations,which generates abundant surface microstrain due to the discrepancy of intermetallic lattice parameters.The unique crystal structure effectively modulates the electron distribution of Pt_(2)CoNi intermetallic nanocatalyst.The active sites of this nanocatalyst exhibit downshifted d-band centers,leading to accelerated hydrogen adsorption/desorption behavior.Resultantly,the Pt_(2)CoNi intermetallic nanocatalyst demonstrates impressive bifunctional hydrogen electrocatalytic capabilities for hydrogen evolution reaction(mass activity of 1.02 A/mg Pt and η_(10) variation of 3.7 mV after 10,000 cycles)and hydrogen oxidation reaction(kinetic mass activity of 4.08 A/mg Pt and 97.3%activity retention after 12 h operating at 0.1 V vs.RHE).This work provides a promising route for the development of efficient nanocatalysts with ingenious crystal structures.
基金supported by Taishan Scholar Program of Shandong Province(No.tsqn202306225)Shandong Postdoctoral Science Foundation(SDBX2023025)+2 种基金Leader of Scientific Research Studio Program of Jinan(No.2021GXRC082)University of Jinan Disciplinary Cross-Convergence Construction Projects 2023(Nos.XKJC-202301 and XKJC-202311)Jinan City-School Integration Development Strategy Project(Nos.JNSX2023015 and JNSX2023018).
文摘The rock-salt cubic SnSe compound with multiple valleys and inherent low thermal conductivity is considered to be a promising thermoelectric compound.In this study,heterogeneous Pb atoms were strategically introduced into the lattice of cubic SnSe matrix,synergistically adjusting the thermoelectric transport properties of samples by optimizing hole carrier concentration(n)and suppressing thermal conductivity(κ_(tot)).When the doping content reached 0.08 mol,the peak power factor(PF)at 300 K increased to 20.00μW·cm^(-1)·K^(-2).The growing internal microstrain induced by the differences in atomic size strengthened the phonon scattering and effectively reduced the lattice thermal conductivity(κ_(L)).With further decoupling of the electrical and thermal transport properties,a peak thermoelectric figure of merit(ZT)of 0.82 and an average ZT of 0.42(300-750 K)were achieved in the samples doped with 0.10 mol Pb.These findings highlight the effectiveness of the selected dopants and demonstrate their synergy in improving the performance of thermoelectric materials.
基金CAS Key Project of Frontier Science Research,Grant/Award Number:QYZDBSSW-SYS030National Natural Science Foundation of China,Grant/Award Numbers:22005322,51773212,81903743+2 种基金National Science Fund for Distinguished Young Scholars,Grant/Award Number:21925506Ningbo S&T Innovation 2025 Major Special Programme,Grant/Award Number:2018B10055National Key R&D Program of China,Grant/Award Number:2017YFE0106000。
文摘All-inorganic perovskite solar cells(PSCs)have developed rapidly in the field of photovoltaics due to their excellent thermal and light stability.However,compared with organic–inorganic hybrid perovskites,the phase instability of inorganic perovskite under humidity still remains as a critical issue that ham-pers the commercialization of inorganic PSCs.We originally propose in this work that microstrains between the perovskite lattices/grains play a key role in affecting the phase stability of inorganic perovskite.To this end,we inno-vatively design theπ-conjugated p-type molecule bis(2-ethylhexyl)3,30((4,8-bis(5-(2-ethylhexyl)-3,4-difluorothiophen-2-yl)benzo[1,2-b:4,5-b0]dithiophene-2,6-di yl)bis(3,300-dioctyl[2,20:50,200-terthiophene]-500,5-diyl))(2E,20 E)-bis(2-cyanoacrylate)(BTEC-2F)to covalent with the Pb dangling bonds in CsPbI2Br perovskite film,which significantly suppress the trap states and release the defect-induced local stress between perovskite grains.The interplay between the microstrains and phase stability of the inorganic perovskite are scrutinized by a series of charac-terizations including x-ray photoelectron spectroscopy,photoluminescence,x-ray diffraction,scanning electron microscopy,and so forth,based on which,we conclude that weaker local stresses in the perovskite film engender superior phase stability by preventing the perovskite lattice distortion under humidity.By this rational design,PSCs based on CsPbI2Br perovskite system deliver an outstanding power conversion efficiency(PCE)up to 16.25%.The unencapsulated device also exhibits an exceptional moisture stability by retaining over 80%of the initial PCE after 500 h aging in ambient with relative humidity of(RH)25%.
文摘We demonstrate for the first time that a short time of microwave irradiation on the oxide precursor of a Cu/ZnO/Al2O3 catalyst can provide unique opportunity for tailoring the microstructure and activity of the catalyst for methanol steam reforming. It is shown by in situ XRD that a considerable increase in the microstrain of Cu nanocrystals could be achieved in the catalysts processed by microwave irradiation for 310 min, which correlates well with the enhanced CH3OH conversion as observed on the corresponding samples. The present work also confirms that although the high specific surface area of Cu is a prerequisite for catalytic activity, it does not account for the observed changes in activity and selectivity alone without taking bulk microstructural changes into account.
