Control of surface structure at the atomic level can effectively tune catalytic properties of nanomaterials.Tuning surface strain is an effective strategy for enhancing catalytic activity;however,the correlation studi...Control of surface structure at the atomic level can effectively tune catalytic properties of nanomaterials.Tuning surface strain is an effective strategy for enhancing catalytic activity;however,the correlation studies between the surface strain with catalytic performance are scant because such mechanistic studies require the precise control of surface strain on catalysts.In this work,a simple strategy of precisely tuning compressive surface strain of atomic-layer Cu2O on Cu@Ag (AL-Cu2O/Cu@Ag) nanoparticles (NPs) is demonstrated.The AL-Cu2O is synthesized by structure evolution of Cu@Ag core-shell nanoparticles,and the precise thickness-control of AL-Cu2O is achieved by tuning the molar ratio of Cu/Ag of the starting material.Aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM) and EELS elemental mapping characterization showed that the compressive surface strain of AL-Cu2O along the [111] and [200] directions can be precisely tuned from 6.5% to 1.6% and 6.6% to 4.7%,respectively,by changing the number of AL-Cu2O layer from 3 to 6.The as-prepared AL-Cu2O/Cu@Ag NPs exhibited excellent catalytic property in the synthesis of azobenzene from aniline,in which the strained 4-layers Cu2O (4.5% along the [111] direction,6.1% along the [200] direction) exhibits the best catalytic performance.This work may be beneficial for the design and surface engineering of catalysts toward specific applications.展开更多
The present study proposes the mix design method of Fly Ash(FA)based geopolymer concrete using Response Surface Methodology(RSM).In this method,different factors,including binder content,alkali/binder ratio,NS/NH rati...The present study proposes the mix design method of Fly Ash(FA)based geopolymer concrete using Response Surface Methodology(RSM).In this method,different factors,including binder content,alkali/binder ratio,NS/NH ratio(sodium silicate/sodium hydroxide),NH molarity,and water/solids ratio were considered for the mix design of geopolymer concrete.The 2D contour plots were used to setup the mix design method to achieve the target compressive strength.The proposed mix design method of geopolymer concrete is divided into three categories based on curing regime,specifically one ambient curing(25°C)and two heat curing(60 and 90°C).The proposed mix design method of geopolymer concrete was validated through experimentation of M30,M50,and M70 concrete mixes at all curing regimes.The observed experimental compressive strength results validate the mix design method by more than 90%of their target strength.Furthermore,the current study concluded that the required compressive strength can be achieved by varying any factor in the mix design.In addition,the factor analysis revealed that the NS/NH ratio significantly affects the compressive strength of geopolymer concrete.展开更多
基金the National Natural Science Foundation of China (Nos.51631001,21643003,51872030,51702016,and 51501010)Fundamental Research Funds for the Central Universities, Beijing Institute of Technology Research Fund Program for Young Scholars and ZDKT18-01 from State Key Laboratory of Explosion Science and Technology (Beijing Institute of Technology).
文摘Control of surface structure at the atomic level can effectively tune catalytic properties of nanomaterials.Tuning surface strain is an effective strategy for enhancing catalytic activity;however,the correlation studies between the surface strain with catalytic performance are scant because such mechanistic studies require the precise control of surface strain on catalysts.In this work,a simple strategy of precisely tuning compressive surface strain of atomic-layer Cu2O on Cu@Ag (AL-Cu2O/Cu@Ag) nanoparticles (NPs) is demonstrated.The AL-Cu2O is synthesized by structure evolution of Cu@Ag core-shell nanoparticles,and the precise thickness-control of AL-Cu2O is achieved by tuning the molar ratio of Cu/Ag of the starting material.Aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM) and EELS elemental mapping characterization showed that the compressive surface strain of AL-Cu2O along the [111] and [200] directions can be precisely tuned from 6.5% to 1.6% and 6.6% to 4.7%,respectively,by changing the number of AL-Cu2O layer from 3 to 6.The as-prepared AL-Cu2O/Cu@Ag NPs exhibited excellent catalytic property in the synthesis of azobenzene from aniline,in which the strained 4-layers Cu2O (4.5% along the [111] direction,6.1% along the [200] direction) exhibits the best catalytic performance.This work may be beneficial for the design and surface engineering of catalysts toward specific applications.
文摘The present study proposes the mix design method of Fly Ash(FA)based geopolymer concrete using Response Surface Methodology(RSM).In this method,different factors,including binder content,alkali/binder ratio,NS/NH ratio(sodium silicate/sodium hydroxide),NH molarity,and water/solids ratio were considered for the mix design of geopolymer concrete.The 2D contour plots were used to setup the mix design method to achieve the target compressive strength.The proposed mix design method of geopolymer concrete is divided into three categories based on curing regime,specifically one ambient curing(25°C)and two heat curing(60 and 90°C).The proposed mix design method of geopolymer concrete was validated through experimentation of M30,M50,and M70 concrete mixes at all curing regimes.The observed experimental compressive strength results validate the mix design method by more than 90%of their target strength.Furthermore,the current study concluded that the required compressive strength can be achieved by varying any factor in the mix design.In addition,the factor analysis revealed that the NS/NH ratio significantly affects the compressive strength of geopolymer concrete.
基金the National Science and Technology Major Project(Grant No.J2019-VIII-0008-0169)the National Natural Science Foundation of China(Grant No.11922211 and 11832015)the 111 Project(Grant No.BP0719007).
