Surface segregation is ubiquitous in multi-component materials and is of great important for catalysis but little is known on the surface structure under graphene encapsulation.Here,we show that the graphene encapsula...Surface segregation is ubiquitous in multi-component materials and is of great important for catalysis but little is known on the surface structure under graphene encapsulation.Here,we show that the graphene encapsulated CoCu performs well for the electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF)to2,5-furandicarboxylic acid(FDCA)with the onset potential before 1.23 VRHEand a nearly 100%selectivity of FDCA under 1.4 VRHE.From the experimental results,the unprecedented catalytic performance was attributed to local structural distortion and sub-nanometer lattice composition of the CoCu surface.We accurately show the dispersed Cu doped Co_(3)O_(4) nano-islands with a lot of edge sites on the bimetallic Co-Cu surface.While,the gradient components effectively facilitate the establishment of built-in electric field and accelerate the charge transfer.Theoretical and experimental results reveal that the surface Co and neighbouring Cu atoms in sub-nanometer lattice synergistically promote the catalysis of HMF.This work offers new insights into surface segregation in tuning the element spatial distribution for catalysis.展开更多
The rational structure design and active-site regulation of catalysts is crucial for high energy output. Herein, B, F co-doped Fe–N–C embedded in a flexible and free-standing hierarchical porous carbon framework(Fe...The rational structure design and active-site regulation of catalysts is crucial for high energy output. Herein, B, F co-doped Fe–N–C embedded in a flexible and free-standing hierarchical porous carbon framework(Fe–SA–FPCS) was reported. Owing to the synergism of optimized intrinsic activity, fast mass transfer and well exposed active sites, the Fe–SA–FPCS exhibits a high halfwave potential(E1/2=0.89 V vs. RHE) and small Tafel slope(66 m V dec^(-1)). Theoretical calculations uncover that B, F co-doping could accelerate the desorption of OH* on Fe sites, which can effectively increase oxygen reduction reaction activity. As the cathode for Zn–air batteries(ZABs), Fe–SA–FPCS demonstrates a high open-circuit voltage(1.51 V), large peak power density(168.4 m W cm^(-2)) and excellent stability. The assembled flexible solid-state ZAB exhibits excellent stability during charge and discharge cycling in the flat/bent state, and is promising for the application of portable and flexible devices. This work provides a new perspective for the fabrication of single-atom electrocatalysts with well-designed structure and excellent electrochemical energy conversion and storage capability.展开更多
基金supported by the National Key R&D Program of China(2020YFA0710000)the National Natural Science Foundation of China(Grant No.:22122901,21902047)the Provincial Natural Science Foundation of Hunan(2020JJ5045,2021JJ20024,2021RC3054)。
文摘Surface segregation is ubiquitous in multi-component materials and is of great important for catalysis but little is known on the surface structure under graphene encapsulation.Here,we show that the graphene encapsulated CoCu performs well for the electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF)to2,5-furandicarboxylic acid(FDCA)with the onset potential before 1.23 VRHEand a nearly 100%selectivity of FDCA under 1.4 VRHE.From the experimental results,the unprecedented catalytic performance was attributed to local structural distortion and sub-nanometer lattice composition of the CoCu surface.We accurately show the dispersed Cu doped Co_(3)O_(4) nano-islands with a lot of edge sites on the bimetallic Co-Cu surface.While,the gradient components effectively facilitate the establishment of built-in electric field and accelerate the charge transfer.Theoretical and experimental results reveal that the surface Co and neighbouring Cu atoms in sub-nanometer lattice synergistically promote the catalysis of HMF.This work offers new insights into surface segregation in tuning the element spatial distribution for catalysis.
基金supported by the National Key R&D Program of China (2020YFA0710000)the National Natural Science Foundation of China (21825201 and U19A2017)+2 种基金the China Postdoctoral Science Foundation (2020M682541)the Science and Technology Innovation Program of Hunan Province, China (2020RC2020)Changsha Municipal Natural Science Foundation (kq2007009)。
文摘The rational structure design and active-site regulation of catalysts is crucial for high energy output. Herein, B, F co-doped Fe–N–C embedded in a flexible and free-standing hierarchical porous carbon framework(Fe–SA–FPCS) was reported. Owing to the synergism of optimized intrinsic activity, fast mass transfer and well exposed active sites, the Fe–SA–FPCS exhibits a high halfwave potential(E1/2=0.89 V vs. RHE) and small Tafel slope(66 m V dec^(-1)). Theoretical calculations uncover that B, F co-doping could accelerate the desorption of OH* on Fe sites, which can effectively increase oxygen reduction reaction activity. As the cathode for Zn–air batteries(ZABs), Fe–SA–FPCS demonstrates a high open-circuit voltage(1.51 V), large peak power density(168.4 m W cm^(-2)) and excellent stability. The assembled flexible solid-state ZAB exhibits excellent stability during charge and discharge cycling in the flat/bent state, and is promising for the application of portable and flexible devices. This work provides a new perspective for the fabrication of single-atom electrocatalysts with well-designed structure and excellent electrochemical energy conversion and storage capability.
