Defect engineering serves as a cornerstone in the design of high-effciency single-atom catalysts(SACs)for advanced electrocatalytic systems.This study demonstrates oxygen vacancy-induced near-zero-valent Pt SACs ancho...Defect engineering serves as a cornerstone in the design of high-effciency single-atom catalysts(SACs)for advanced electrocatalytic systems.This study demonstrates oxygen vacancy-induced near-zero-valent Pt SACs anchored on TiO2 for efficient hydrogen evolution reaction(HER).Synchrotron spectroscopy and density functional theory calculation reveal that oxygen vacancies create unconventional Pt-Ti coordination while strengthening electronic metal-support interactions.This facilitates substantial electron transfer from TiO2 to Pt,generating a near-zero-valent Pt state with elevated electron density.The modified electronic structure lowers the Pt d-band center,reducing hydrogen intermediate(*H)adsorption energy and optimizing HER kinetics.Moreover,ab initio molecular dynamics and in situ Raman spectra show that the negative charge accumulated at the Pt site promotes K^(+)enrichment at the interface,which enhances H-OH bond polarization and accelerates water dissociation kinetics.The resulting D-TiO_(2)/Pt SACs exhibit superior HER activity across acidic,neutral,and alkaline conditions,achieving low overpotentials of 40,57,and 60 mV at 10 mA cm^(-2),respectively.Additionally,its mass activities at the overpotential of 100 mV are 10.3,33.9,and 20.9 times higher that of Pt/C,respectively.This study shows the key role of defectmediated electronic engineering in tailoring SACs'valence states and catalytic functions,advancing sustainable hydrogen production through rational catalyst design.展开更多
Magnesium composites reinforced by N-deficient Ti_(2)AlN MAX phase were first fabricated by non-pressure infiltration of Mg into three-dimensional(3D)co-continuous porous Ti_(2)AlN_(x)(x=0.9,1.0)preforms.The relations...Magnesium composites reinforced by N-deficient Ti_(2)AlN MAX phase were first fabricated by non-pressure infiltration of Mg into three-dimensional(3D)co-continuous porous Ti_(2)AlN_(x)(x=0.9,1.0)preforms.The relationship between their mechanical properties and micro-structure is discussed with the assessment of 2D and 3D characterization.X-ray diffraction(XRD)and scanning electron microscopy detected no impurities.The 3D reconstruction shows that the uniformly distributed pores in Ti_(2)AlN_(x) preforms are interconnected,which act as infiltra-tion tunnels for the melt Mg.The compressive yield strength and microhardness of Ti_(2)AlN_(0.9)/Mg are 353 MPa and 1.12 GPa,respectively,which are 8.55%and 6.67%lower than those of Ti_(2)AlN/Mg,respectively.The typical delamination and kink band occurred in Ti_(2)AlN_(x) under compressive and Vickers hardness(V_(H))tests.Owing to the continuous skeleton structure and strong interfacial bonding strength,the crack ini-tiated in Ti_(2)AlN_(x) was blocked by the plastic Mg matrix.This suggests the possibility of regulating the mechanical performance of Ti_(2)AlN/Mg composites by controlling the N vacancy and the hierarchical structure of Ti_(2)AlN skeleton.展开更多
基金financially supported by the National Oversea Postdoctoral Talent Attraction Programthe Pilot Group Program of the Research Fund for International Senior Scientists(52350710795)+2 种基金the Youth Fund of the National Natural Science Foundation of China(52402288)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(YESS20230183)the Yangfan Special Program of Shanghai Star Project(24YF2729700)。
文摘Defect engineering serves as a cornerstone in the design of high-effciency single-atom catalysts(SACs)for advanced electrocatalytic systems.This study demonstrates oxygen vacancy-induced near-zero-valent Pt SACs anchored on TiO2 for efficient hydrogen evolution reaction(HER).Synchrotron spectroscopy and density functional theory calculation reveal that oxygen vacancies create unconventional Pt-Ti coordination while strengthening electronic metal-support interactions.This facilitates substantial electron transfer from TiO2 to Pt,generating a near-zero-valent Pt state with elevated electron density.The modified electronic structure lowers the Pt d-band center,reducing hydrogen intermediate(*H)adsorption energy and optimizing HER kinetics.Moreover,ab initio molecular dynamics and in situ Raman spectra show that the negative charge accumulated at the Pt site promotes K^(+)enrichment at the interface,which enhances H-OH bond polarization and accelerates water dissociation kinetics.The resulting D-TiO_(2)/Pt SACs exhibit superior HER activity across acidic,neutral,and alkaline conditions,achieving low overpotentials of 40,57,and 60 mV at 10 mA cm^(-2),respectively.Additionally,its mass activities at the overpotential of 100 mV are 10.3,33.9,and 20.9 times higher that of Pt/C,respectively.This study shows the key role of defectmediated electronic engineering in tailoring SACs'valence states and catalytic functions,advancing sustainable hydrogen production through rational catalyst design.
基金financially supported by the National Natural Science Foundation of China(No.52175284)the State Key Lab of Advanced Metals and Materials(No.2021-ZD08)the Beijing Government Funds for the Cons tructive Project of Central Universities(No.353139535)。
文摘Magnesium composites reinforced by N-deficient Ti_(2)AlN MAX phase were first fabricated by non-pressure infiltration of Mg into three-dimensional(3D)co-continuous porous Ti_(2)AlN_(x)(x=0.9,1.0)preforms.The relationship between their mechanical properties and micro-structure is discussed with the assessment of 2D and 3D characterization.X-ray diffraction(XRD)and scanning electron microscopy detected no impurities.The 3D reconstruction shows that the uniformly distributed pores in Ti_(2)AlN_(x) preforms are interconnected,which act as infiltra-tion tunnels for the melt Mg.The compressive yield strength and microhardness of Ti_(2)AlN_(0.9)/Mg are 353 MPa and 1.12 GPa,respectively,which are 8.55%and 6.67%lower than those of Ti_(2)AlN/Mg,respectively.The typical delamination and kink band occurred in Ti_(2)AlN_(x) under compressive and Vickers hardness(V_(H))tests.Owing to the continuous skeleton structure and strong interfacial bonding strength,the crack ini-tiated in Ti_(2)AlN_(x) was blocked by the plastic Mg matrix.This suggests the possibility of regulating the mechanical performance of Ti_(2)AlN/Mg composites by controlling the N vacancy and the hierarchical structure of Ti_(2)AlN skeleton.
