Magnesium hydride serves as a promising solid-state hydrogen storage material owing to its high potential.However,its practical applications are constrained by the high enthalpy of hydrogen absorption and slow kinetic...Magnesium hydride serves as a promising solid-state hydrogen storage material owing to its high potential.However,its practical applications are constrained by the high enthalpy of hydrogen absorption and slow kinetics.In this study,we prepared a Ni/Ti3O5@graphene oxide(GO)dual-heterojunction composite material via solvent heating,electrostatic adsorption,and calcination to improve the hydrogen storage capabilities of MgH2.Adding Ni/Ti3O5@GO to MgH2 lowered the initial dehydrogenation temperature of MgH2 to 183℃;at a dehydrogenation temperature of 275℃,6.4 wt.%of H2 escaped from the MgH2 bulk.In addition,the hydrogen storage material absorbed 1.8 wt.%H2 at 30℃ for 30 min.The calculated activation energy of dehydrogenation was 48.221±0.141 kJ·mol-1,which was significantly lower than that of the ball-milled MgH2(112.63±1.44 kJ·mol-1).Mechanistic analysis results revealed that the heterojunction constructed from the multiphase compound system provided a large number of active sites and hydrogen diffusion routes,resulting in a synergistic catalytic effect that enhanced the hydrogen storage capacity of MgH2.In this work,we clarified the compositions of fuzzy interfaces in heterostructured materials by conducting ultraviolet photoelectron spectroscopy tests and identified key composite materials for the formation of heterojunctions.展开更多
The stereodivergent coupling via photoredoxransition metal catalysis has emerged as a powerful tool to construct diverse alkenes in both E and Z configurations.Despite well-established catalytic systems involving late...The stereodivergent coupling via photoredoxransition metal catalysis has emerged as a powerful tool to construct diverse alkenes in both E and Z configurations.Despite well-established catalytic systems involving late transition metals,the early transition metal catalyzed stereodivergent synthesis of alkenes still remains underdeveloped.Herein in this work,a stereodivergent reductive C(sp2)-C(sp3)coupling between cycloketone oximes and vinyl halides has been achieved by tunable photoredox/Ti dual catalysis,providing a facile access to a broad scope of cyano-substituted(fluoro)alkenes with high efficiency and controlled E/Z selectivity.Several products exhibited promising antifungal activities.展开更多
The influence of 0.1 wt.%Ti and Ti/B on Zn-6 wt.%Al-3 wt.%Mg coating alloy during rapid cooling(50-75℃/s)was investigated.The results demonstrate a significant change in the microstructure of the alloy upon the intro...The influence of 0.1 wt.%Ti and Ti/B on Zn-6 wt.%Al-3 wt.%Mg coating alloy during rapid cooling(50-75℃/s)was investigated.The results demonstrate a significant change in the microstructure of the alloy upon the introduction of Ti or Ti/B.Al dendrites undergo a transition from slender to short and coarse,and more Al dendrites are produced.The ternary eutectic Zn/Al/Mg2Zn11phase is no longer observed,while only the ternary eutectic Zn/Al/MgZn2phase is present.The addition of Ti results in the formation of a precipitated phase consisting of TiAl3and when Ti/B is added,both TiAl3and TiB2 phases are observed to precipitate.The solid solubility of Mg in Zn can be influenced by Ti,as demonstrated through composition profile,thermodynamic calculation,and diffusion couple experiments.Zn phase nucleates as the priority phase when the eutectic phase precipitates.Due to the significant supercooling,rapid growth of Zn phase occurs,accompanied by solid dissolution of some Mg and Al into Zn phase because of insufficient time for diffusion outside.The interface of Zn phase exhibits a low concentration of Mg,resulting in the formation of Mg2Zn11nuclei.After the solid solution of Ti in Zn phase,more Mg and Al will be discharged,and MgZn2nuclei will be generated at the higher concentration of Mg at the interface of Zn phase.By elucidating the solidification mechanism,a deeper comprehension of the role of Ti in Zn-6Al-3Mg alloy can be attained.展开更多
Cr2O3was used as grain inhibitor in Ti(C,N)-based cermets with vacuum sintering.The microstructure and mechanical and tribological properties of cermets with Cr2O3and Cr3C2were investigated.The resul...Cr2O3was used as grain inhibitor in Ti(C,N)-based cermets with vacuum sintering.The microstructure and mechanical and tribological properties of cermets with Cr2O3and Cr3C2were investigated.The results show that adding Cr2O3promotes a gray core/gray rim structure formation and finer size of Ti(C,N)hard phase.Compared with the cermet with an equal Cr3C2addition,the cermet with 0.6 wt.%Cr2O3exhibits 16.5%higher transverse rupture strength.This enhancement is likely due to the smaller lattice misfit at the coreim interface and more uniform Cr distribution in the binder.Additionally,at room temperature(25℃)and 800℃,Cr2O3-containing cermets demonstrate lower coefficients of friction and volume wear ratios than Cr3C2-containing cermets,with the wear ratio difference reaching an order of magnitude.Scanning electron microscopy and X-ray photoelectron spectroscopy results further confirm more oxidation wear in Cr2O3-containing cermets than in Cr3C2-containing cermets.展开更多
Formaldehyde(HCHO) is a common indoor pollutant, long-term exposure to HCHO may harm human health. Its efficient removal at mild conditions is still challenging. The catalytic oxidation of HCHO molecules on a single a...Formaldehyde(HCHO) is a common indoor pollutant, long-term exposure to HCHO may harm human health. Its efficient removal at mild conditions is still challenging. The catalytic oxidation of HCHO molecules on a single atomic catalyst, Ti-decorated Ti3C2O2(Ti/Ti3C2O2) monolayer, is investigated by performing the first principles calculations in this work. It demonstrates that Ti atoms can be easily well dispersed at the form of single atom on Ti3C2O2 monolayer without aggregation. For HCHO catalytic oxidation, both Langmuir-Hinshelwood(LH) and Eley-Rideal(ER) mechanisms are considered. The results show that the step of HCHO dissociative adsorption on Ti/Ti3C2O2 with activated O2 can release high energy of 4.05 e V based on the ER mechanism, which can help to overcome the energy barrier(1.04 e V) of the subsequent reaction steps. The charge transfer from *OH group to CO molecule(dissociated from HCHO) not only promotes *OH group activation but also plays an important role in the H2 O generation along the ER mechanism. Therefore, HCHO can be oxidized easily on Ti/Ti3C2O2 monolayer, this work could provide significant guidance to develop effective non-noble metal catalysts for HCHO oxidation and broaden the applications of MXene-based materials.展开更多
Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be...Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be addressed which impede Ti3C2Tx obtaining the ideal specific capacitance,such as restacking,re-crushing,and oxidation of titanium.Recently,many advances have been proposed to enhance capacitance performance of Ti3C2Tx.In this review,recent strategies for improving specific capacitance are summarized and compared,for example,film formation,surface modification,and composite method.Furthermore,in order to comprehend the mechanism of those efforts,this review analyzes the energy storage performance in different electrolytes and influencing factors.This review is expected to predict redouble research direction of Ti3C2Tx materials in supercapacitors.展开更多
基金supported by the National Natural Science Foundation of China[grant number U24A2044]Science and Technology Major Program of Guangxi Province[grant number GUIKEAA24206007].
摘要Magnesium hydride serves as a promising solid-state hydrogen storage material owing to its high potential.However,its practical applications are constrained by the high enthalpy of hydrogen absorption and slow kinetics.In this study,we prepared a Ni/Ti3O5@graphene oxide(GO)dual-heterojunction composite material via solvent heating,electrostatic adsorption,and calcination to improve the hydrogen storage capabilities of MgH2.Adding Ni/Ti3O5@GO to MgH2 lowered the initial dehydrogenation temperature of MgH2 to 183℃;at a dehydrogenation temperature of 275℃,6.4 wt.%of H2 escaped from the MgH2 bulk.In addition,the hydrogen storage material absorbed 1.8 wt.%H2 at 30℃ for 30 min.The calculated activation energy of dehydrogenation was 48.221±0.141 kJ·mol-1,which was significantly lower than that of the ball-milled MgH2(112.63±1.44 kJ·mol-1).Mechanistic analysis results revealed that the heterojunction constructed from the multiphase compound system provided a large number of active sites and hydrogen diffusion routes,resulting in a synergistic catalytic effect that enhanced the hydrogen storage capacity of MgH2.In this work,we clarified the compositions of fuzzy interfaces in heterostructured materials by conducting ultraviolet photoelectron spectroscopy tests and identified key composite materials for the formation of heterojunctions.
基金the National Natural Science Foundation of China(Nos.22101135,22271293 and 21502096)the Natural Science Foundation of Jiangsu Province(Nos.BK20210381 and BK20150652)+3 种基金the Fundamental Research Funds for the Central Universities(Nos.KYQN2022058,KJQN201629,and XUEKEN2022032)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0960000)CAS Project for Young Scientists in Basic Research(No.YSBR-050)the Chinese Academy of Sciences and the“333 High Level Talent Project”of Jiangsu Province for financial support。
摘要The stereodivergent coupling via photoredoxransition metal catalysis has emerged as a powerful tool to construct diverse alkenes in both E and Z configurations.Despite well-established catalytic systems involving late transition metals,the early transition metal catalyzed stereodivergent synthesis of alkenes still remains underdeveloped.Herein in this work,a stereodivergent reductive C(sp2)-C(sp3)coupling between cycloketone oximes and vinyl halides has been achieved by tunable photoredox/Ti dual catalysis,providing a facile access to a broad scope of cyano-substituted(fluoro)alkenes with high efficiency and controlled E/Z selectivity.Several products exhibited promising antifungal activities.
基金support from Science and Technology Committee of Shanghai(Grant No.21ZR1423600)Central Government Guides the Development of Local Science and Technology Special Fund of China(Grant No.216Z1004G)+1 种基金the support from Ningbo Yongjiang Talent Introduction Programme(2022A-023-C)Zhejiang Phenomenological Materials Technology Co.,Ltd.,China.
摘要The influence of 0.1 wt.%Ti and Ti/B on Zn-6 wt.%Al-3 wt.%Mg coating alloy during rapid cooling(50-75℃/s)was investigated.The results demonstrate a significant change in the microstructure of the alloy upon the introduction of Ti or Ti/B.Al dendrites undergo a transition from slender to short and coarse,and more Al dendrites are produced.The ternary eutectic Zn/Al/Mg2Zn11phase is no longer observed,while only the ternary eutectic Zn/Al/MgZn2phase is present.The addition of Ti results in the formation of a precipitated phase consisting of TiAl3and when Ti/B is added,both TiAl3and TiB2 phases are observed to precipitate.The solid solubility of Mg in Zn can be influenced by Ti,as demonstrated through composition profile,thermodynamic calculation,and diffusion couple experiments.Zn phase nucleates as the priority phase when the eutectic phase precipitates.Due to the significant supercooling,rapid growth of Zn phase occurs,accompanied by solid dissolution of some Mg and Al into Zn phase because of insufficient time for diffusion outside.The interface of Zn phase exhibits a low concentration of Mg,resulting in the formation of Mg2Zn11nuclei.After the solid solution of Ti in Zn phase,more Mg and Al will be discharged,and MgZn2nuclei will be generated at the higher concentration of Mg at the interface of Zn phase.By elucidating the solidification mechanism,a deeper comprehension of the role of Ti in Zn-6Al-3Mg alloy can be attained.
基金Natural Science Foundation of Ningxia,China(No.2023AAC03284)Fundamental Research Funds for the Central Universities Research Project of North Minzu University,China(No.2022XYZCL04)+1 种基金Project of Key Laboratory of Powders and Advanced CeramicsCo-founded by Ningxia and the State Ethnic Affairs Commission,China(No.2103)。
摘要Cr2O3was used as grain inhibitor in Ti(C,N)-based cermets with vacuum sintering.The microstructure and mechanical and tribological properties of cermets with Cr2O3and Cr3C2were investigated.The results show that adding Cr2O3promotes a gray core/gray rim structure formation and finer size of Ti(C,N)hard phase.Compared with the cermet with an equal Cr3C2addition,the cermet with 0.6 wt.%Cr2O3exhibits 16.5%higher transverse rupture strength.This enhancement is likely due to the smaller lattice misfit at the coreim interface and more uniform Cr distribution in the binder.Additionally,at room temperature(25℃)and 800℃,Cr2O3-containing cermets demonstrate lower coefficients of friction and volume wear ratios than Cr3C2-containing cermets,with the wear ratio difference reaching an order of magnitude.Scanning electron microscopy and X-ray photoelectron spectroscopy results further confirm more oxidation wear in Cr2O3-containing cermets than in Cr3C2-containing cermets.
摘要Formaldehyde(HCHO) is a common indoor pollutant, long-term exposure to HCHO may harm human health. Its efficient removal at mild conditions is still challenging. The catalytic oxidation of HCHO molecules on a single atomic catalyst, Ti-decorated Ti3C2O2(Ti/Ti3C2O2) monolayer, is investigated by performing the first principles calculations in this work. It demonstrates that Ti atoms can be easily well dispersed at the form of single atom on Ti3C2O2 monolayer without aggregation. For HCHO catalytic oxidation, both Langmuir-Hinshelwood(LH) and Eley-Rideal(ER) mechanisms are considered. The results show that the step of HCHO dissociative adsorption on Ti/Ti3C2O2 with activated O2 can release high energy of 4.05 e V based on the ER mechanism, which can help to overcome the energy barrier(1.04 e V) of the subsequent reaction steps. The charge transfer from *OH group to CO molecule(dissociated from HCHO) not only promotes *OH group activation but also plays an important role in the H2 O generation along the ER mechanism. Therefore, HCHO can be oxidized easily on Ti/Ti3C2O2 monolayer, this work could provide significant guidance to develop effective non-noble metal catalysts for HCHO oxidation and broaden the applications of MXene-based materials.
基金National Natural Science Foundation of China with Grant No.21905304Natural Science Foundation of Shandong Province(No.ZR2019BEM031)the Fundamental Research Funds for the Central Universities(Nos.18CX02158A and 19CX05001A).
摘要Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be addressed which impede Ti3C2Tx obtaining the ideal specific capacitance,such as restacking,re-crushing,and oxidation of titanium.Recently,many advances have been proposed to enhance capacitance performance of Ti3C2Tx.In this review,recent strategies for improving specific capacitance are summarized and compared,for example,film formation,surface modification,and composite method.Furthermore,in order to comprehend the mechanism of those efforts,this review analyzes the energy storage performance in different electrolytes and influencing factors.This review is expected to predict redouble research direction of Ti3C2Tx materials in supercapacitors.