Limited by the sluggish kinetics at the cathode of proton exchange membrane fuel cells(PEMFCs),optimizing platinum-based alloy catalysts for oxygen reduction reaction remains a key target toward industrialization.Stra...Limited by the sluggish kinetics at the cathode of proton exchange membrane fuel cells(PEMFCs),optimizing platinum-based alloy catalysts for oxygen reduction reaction remains a key target toward industrialization.Strain engineering is widely employed to tune Pt-M catalysts,but its impact on the structure-property relationship is often interwoven with multiple factors.In this work,we propose a bi-stage strain tuning method and demonstrate it on the most common PtCo catalysts.Macro-strain is introduced by synthesizing single-crystal PtCo nanodendrites,whereas mild acid etching introduces micro-strain to the surface.The half-wave potential of as-treated catalysts reaches 0.959 V,and mass activity is up to 0.69 A mg^(−1)_(Pt).A minimal decrease of 2 mV is observed for half-wave potential after 10,000 cycles.Detailed analysis using advanced transmission electron microscopy,wide-angle X-ray scattering,etc.provides direct evidence that surface disorder at the atomic scale accounts for the enhanced activity and stability.In contrast,the simplicity of this approach allows for scaling up on Pt-M catalysts,as demonstrated on PEMFCs.The bi-stage strain tuning strategy provides a new perspective and reference for improving the activity and durability of Pt-M catalysts.展开更多
The recent report of superconductivity in nitrogen-doped lutetium hydride(Lu-H-N)at 294 K and 1 GPa brought hope for long-sought-after ambient-condition superconductors.However,the failure of scientists worldwide to i...The recent report of superconductivity in nitrogen-doped lutetium hydride(Lu-H-N)at 294 K and 1 GPa brought hope for long-sought-after ambient-condition superconductors.However,the failure of scientists worldwide to independently reproduce these results has cast intense skepticism on this exciting claim.In this work,using a reliable experimental protocol,we synthesized Lu-H-N while minimizing extrinsic influences and reproduced the sudden change in resistance near room temperature.With quantitative comparison of the temperaturedependent resistance between Lu-H-N and the pure lutetium before reaction,we were able to clarify that the drastic resistance change is most likely caused by a metal-to-poor-conductor transition rather than by superconductivity.Herein,we also briefly discuss other issues recently raised in relation to the Lu-H-N system.展开更多
Li-rich layered oxides(LRLOs)materials have been considered as one of the most promising cathode materials for next-generation lithium-ion batteries.However,LRLOs suffer from continuous phase transition from the layer...Li-rich layered oxides(LRLOs)materials have been considered as one of the most promising cathode materials for next-generation lithium-ion batteries.However,LRLOs suffer from continuous phase transition from the layered to rock-salt phase during cycling,and its origin still remains unclear.Here,we reveal that the accumulation of rock-salt phases originates from the compressive strain induced by phase transitions in which the initial surface rock-salt phase compresses its neighboring layered phase and further causes lattice contraction of the layered phase.This compressed layered phase always existed on the particle surface,leading to the rocksalt phase not completely covering the surface of the LRLOs particles.Also,the compressed layered phase can serve as an oxygen loss channel to lure the generation of more rock-salt phase,resulting in the phase transition gradually extending inwards.Based on this finding,we construct a uniform coherent spinel structure as a surface protection layer to suppress oxygen loss and the interior extension of rock-salt phase during cycling.As a result,the improved cathode materials demonstrate 99%voltage retention after 100 cycles.This work solves the surface inhomogeneous phase evolution of LRLOs,contributing to enhanced sustainability of high energy density cathode materials.展开更多
The growing usage of industrial dyes makes the sewage treatment a global issue,therefore low-cost,highly efficient catalysts are urgently demanded for wastewater purification.We present an ultrasonic-engineered cataly...The growing usage of industrial dyes makes the sewage treatment a global issue,therefore low-cost,highly efficient catalysts are urgently demanded for wastewater purification.We present an ultrasonic-engineered catalytic technology,which can achieve an extremely high efficiency in azo dye degradation via a tiny dosage of 0.1 gL^(-1)(only one-fifth of the normally used dosage)Fe_(81)Si_(9)B_(10)amorphous powders(APs)with a low activation energy of 45.32 kJ mol^(-1)and a high reaction rate of 0.70291 min^(-1).The non-destructive ultrasonic vibration(UV)treatment with very short processing times(0.43-1.08 s)amplifies degradation efficiency by an astonishing 55-fold compared to untreated APs.Combined with high-energy X-ray diffraction and small-angle neutron scattering analyses,we reveal that the UV-induced structural reconstruction at both shortand medium-range order effectively lower reaction energy barriers while accelerating charge transfer kinetics.The high-energy ultrasonic attacks promote the exposure of massive fresh active sites,which enhance the Fe^(2+)/Fe^(3+)redox circulation and thereby lead to the fast Fenton-like oxidation processes.By integrating ultrasonic physics with amorphous materials,this work develops an energy-efficient catalytic activation method,enabling sustainable water purification and innovative pollutant treatment strategies.展开更多
基金the National Natural Science Foundation of China(NO.12274010,12474003)Beijing Nova Program(20240484584)+2 种基金the support from the Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments,China(No.22dz2260800)the Shanghai Science and Technology Committee,China(No.22JC1410300)the National Natural Science Foundation of China(No.52103330)。
文摘Limited by the sluggish kinetics at the cathode of proton exchange membrane fuel cells(PEMFCs),optimizing platinum-based alloy catalysts for oxygen reduction reaction remains a key target toward industrialization.Strain engineering is widely employed to tune Pt-M catalysts,but its impact on the structure-property relationship is often interwoven with multiple factors.In this work,we propose a bi-stage strain tuning method and demonstrate it on the most common PtCo catalysts.Macro-strain is introduced by synthesizing single-crystal PtCo nanodendrites,whereas mild acid etching introduces micro-strain to the surface.The half-wave potential of as-treated catalysts reaches 0.959 V,and mass activity is up to 0.69 A mg^(−1)_(Pt).A minimal decrease of 2 mV is observed for half-wave potential after 10,000 cycles.Detailed analysis using advanced transmission electron microscopy,wide-angle X-ray scattering,etc.provides direct evidence that surface disorder at the atomic scale accounts for the enhanced activity and stability.In contrast,the simplicity of this approach allows for scaling up on Pt-M catalysts,as demonstrated on PEMFCs.The bi-stage strain tuning strategy provides a new perspective and reference for improving the activity and durability of Pt-M catalysts.
文摘The recent report of superconductivity in nitrogen-doped lutetium hydride(Lu-H-N)at 294 K and 1 GPa brought hope for long-sought-after ambient-condition superconductors.However,the failure of scientists worldwide to independently reproduce these results has cast intense skepticism on this exciting claim.In this work,using a reliable experimental protocol,we synthesized Lu-H-N while minimizing extrinsic influences and reproduced the sudden change in resistance near room temperature.With quantitative comparison of the temperaturedependent resistance between Lu-H-N and the pure lutetium before reaction,we were able to clarify that the drastic resistance change is most likely caused by a metal-to-poor-conductor transition rather than by superconductivity.Herein,we also briefly discuss other issues recently raised in relation to the Lu-H-N system.
基金supported by the Natural Science Foundation of Tianjin(grant nos.24JCJQJC00220 and 24ZXZSSS00390)the National Natural Science Foundation of China(grant nos.22479080,22121005,92372203,and 92372001)+1 种基金the Open Foundation of Shanghai Jiao Tong University Shaoxing Research Institute of Renewable Energy and Molecular Engineering(grant no.JDSX2023003)the Fundamental Research Funds for the Central Universities of Nankai University(grant nos.63241206 and 9242000710).
文摘Li-rich layered oxides(LRLOs)materials have been considered as one of the most promising cathode materials for next-generation lithium-ion batteries.However,LRLOs suffer from continuous phase transition from the layered to rock-salt phase during cycling,and its origin still remains unclear.Here,we reveal that the accumulation of rock-salt phases originates from the compressive strain induced by phase transitions in which the initial surface rock-salt phase compresses its neighboring layered phase and further causes lattice contraction of the layered phase.This compressed layered phase always existed on the particle surface,leading to the rocksalt phase not completely covering the surface of the LRLOs particles.Also,the compressed layered phase can serve as an oxygen loss channel to lure the generation of more rock-salt phase,resulting in the phase transition gradually extending inwards.Based on this finding,we construct a uniform coherent spinel structure as a surface protection layer to suppress oxygen loss and the interior extension of rock-salt phase during cycling.As a result,the improved cathode materials demonstrate 99%voltage retention after 100 cycles.This work solves the surface inhomogeneous phase evolution of LRLOs,contributing to enhanced sustainability of high energy density cathode materials.
基金supported by the National Natural Science Foundation of China(Grant Nos.52071078,and 52401201)the“Zhishan”Scholars Programs of Southeast University(Grant No.2242021R41158)+1 种基金the Jiangsu Key Laboratory for Advanced Metallic Materials(Grant No.BM2007204)supported by the Big Data Computing Center of Southeast University。
文摘The growing usage of industrial dyes makes the sewage treatment a global issue,therefore low-cost,highly efficient catalysts are urgently demanded for wastewater purification.We present an ultrasonic-engineered catalytic technology,which can achieve an extremely high efficiency in azo dye degradation via a tiny dosage of 0.1 gL^(-1)(only one-fifth of the normally used dosage)Fe_(81)Si_(9)B_(10)amorphous powders(APs)with a low activation energy of 45.32 kJ mol^(-1)and a high reaction rate of 0.70291 min^(-1).The non-destructive ultrasonic vibration(UV)treatment with very short processing times(0.43-1.08 s)amplifies degradation efficiency by an astonishing 55-fold compared to untreated APs.Combined with high-energy X-ray diffraction and small-angle neutron scattering analyses,we reveal that the UV-induced structural reconstruction at both shortand medium-range order effectively lower reaction energy barriers while accelerating charge transfer kinetics.The high-energy ultrasonic attacks promote the exposure of massive fresh active sites,which enhance the Fe^(2+)/Fe^(3+)redox circulation and thereby lead to the fast Fenton-like oxidation processes.By integrating ultrasonic physics with amorphous materials,this work develops an energy-efficient catalytic activation method,enabling sustainable water purification and innovative pollutant treatment strategies.
