Tensile and Fatigue Properties of Free-Standing Cu Foils

Tensile and fatigue properties of free-standing as-rolled Cu foils were investigated by means of uniaxial tensile and dynamic bending tests. A special testing system was established to evaluate fatigue behavior of a microscale material subjected to dynamic bending load. The experimental results show that the yield strength increases, but the fracturestrain and fatigue resistance decrease with decreasing foil thickness. Deformation and fatigue damage behavior was characterized. The size effect on tensile and fatigue properties of the Cu foils are evaluated to get further understanding of the mechanical behavior of the micrometer-scale metallic materials.

Silane coupling agent treated copper foil as a current collector for silicon anode

Since the volume variation of silicon particles during cycling,the binding spots between Cu current collector and silicon anode raised to be one of the critical binding problems.In this work,an amino-modified Cu current collector(Cu^(*))is fabricated to tackle this issue.The amino groups on Cu^(*)surface increase its hydrophilicity,which is conducive to the curing process of aqueous slurry on its surface.Meanwhile,these amino groups can form abundant amide bonds with carboxyl groups from the adopted polyacrylic acid(PAA)binder.The combined action composed of the covalent bond and mechanical interlocking could reduce the contact loss inside the electrode.However,high concentration silane coupling agent treatment will weaken the surface roughness of Cu^(*)and weaken mechanical interlocking.What is more,the insulation of silane coupling agent reduces the conductivity of Cu and increases the impedance of battery.Considering the effect of silane coupling agent comprehensively,electrochemical performance of Cu^(*)-0.05%is best.

ZnO Nanobelts and Hollow Microspheres Grown on Cu Foil

ZnO nanobelts, hollow microspheres, and urchins have been prepared on copper foil via a simply low temperature evaporation route. The microstructure, morphologies, and photolu-minescence of the ZnO nanostructures were studied with X-ray diffraction, Raman spectra, scanning electron microscopy and photoluminescence spectra. The width of the nanobelts was about 500 nm and the length was longer than 10μm. The diameter of the hollow microspheres was between 5 and 10μm. A possible growth mechanism of the nanobelts, microspheres and urchins was proposed. The photoluminescence spectrum exhibited strong deep level energy emissions and a weak near band edge emission. These ZnO nanostructures on a copper substrate have the advantages of naturally good adhesion and electrical connection between the ZnO nanostructures and the conductive substrate.

Mechanically induced Cu active sites for selective C–C coupling in CO_(2)electroreduction

Developing a convenient method to endow bulk Cu-based electrode with high activity of electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to multicarbon(C_(2+))products is desirable but challenging.Herein,for the first time,we report that mechanical polishing induces highly reactive Cu sites for selective C-C coupling in CO_(2)RR.We find that mechanical polishing could endow Cu foil with abundant nanocavity surface structure,which efficiently confines the carbonaceous intermediates to enhance the probability of C-C coupling reaction.By confining the carbonaceous intermediates with Cu nanocavity,the as-prepared electrode delivers a Faradaic efficiency toward C_(2+)products of 65.7%at-1.3 V vs.RHE,which is enhanced up to 1.7 folds compared with that of commercial Cu foil.This work provides a new method to enable Cu foil with high activity of CO_(2)RR to C_(2+)products.

Metal-organic layers induce in situ nano-structuring of Cu surface in electrocatalytic CO_(2)reduction

Cu-based catalysts have attracted widespread attention for its capability in electrocatalytically reducing CO_(2)to a variety of products.Surface modification of Cu has become an interesting method for tuning the catalytic performance.Here,we use Zrbased metal-organic layers(MOLs)as the additive of the Cu surface,which enhanced the Faradaic efficiency of CH4 by two times as compared to the untreated polycrystalline Cu foil.Unexpectedly,the MOLs were found to induce in situ nano-structuring of the Cu foil surface within seconds in the electrolysis,as revealed by a combination of scanning electron microscopy(SEM),grazing incidence X-ray diffractometry(GIXRD),and linear sweep voltammetry(LSV)measurements.These surface changes are responsible for the shift of product selectivity.Control experiments suggest that negatively chargedμ3-O−on the Zr-cluster in the MOL might interact with CO-covered Cu surface and induce roughing and nano-structuring.This work reveals a potential role of additive on Cu to induce surface nano-structuring that tunes catalytic activity and selectivity.

High-quality bilayer graphene grown on softened copper foils by atmospheric pressure chemical vapor deposition

Bilayer graphene(BLG)shows great application prospect and potential in next-generation electronics because of its unique electrical and mechanical properties.However,the scalable synthesis of large-area high-quality BLG films is still a great challenge,despite the maturity of chemical vapor deposition(CVD)technique.In this study,we report a robust method to grow BLGs on flat,softened Cu foils by atmospheric pressure CVD.A moderate amount of residual oxygen accelerates the growth of BLG domains while suppressing the formation of multilayers.Raising the nucleation density at low hydrogen pressure efficiently increases the film continuity.Based on the optimized CVD process,the growth of graphene films on 4×4 cm^2 Cu foils with an average BLG coverage of 76%is achieved.The morphology and structure characterizations demonstrate a high quality of the BLG.Dual gate field-effect transistors are investigated based on AB-stacked BLG,with a tunable bandgap and high carrier mobility of up to 6790 cm2 V^−1 s^−1 at room temperature.

The role of Cu crystallographic orientations towards growing superclean graphene on meter-sized scale

Chemical vapor deposition(CVD)-grown graphene films on Cu foils,exhibiting fine scalability and high quality,are still suffering from the adverse impact of surface contamination,i.e.,amorphous carbon.Despite the recent successful preparation of superclean graphene through Cu-vapor-assisted reactions,the formation mechanism of amorphous carbon remains unclear,especially with regard to the functions of substrates.Herein,we have found that the crystallographic orientations of underlying metal substrates would determine the cleanness of graphene in such a way that slower diffusion of active carbon species on asformed graphene-Cu(100)surface is the key factor that suppresses the formation of contamination.The facile synthesis of clean graphene is achieved on the meter-sized Cu(100)that is transformed from the polycrystalline Cu foils.Furthermore,a clean surface of graphene on Cu(100)ensures the reduction of transfer-related polymer residues,and enhanced optical and electrical performance,which allows for versatile applications of graphene in biosensors,functioning as flexible transparent electrodes.This work would offer a promising material platform for the fundamental investigation and create new opportunities for the advanced applications of high-quality graphene films.

Chemical vapor deposition growth of large-scale hexagonal boron nitride with controllable orientation

Chemical vapor deposition （CVD） synthesis of large-domain hexagonal boron nitride （h-BN） with a uniform thickness is very challenging, mainly due to the extremely high nucleation density of this material. Herein, we report the successful growth of wafer-scale, high-quality h-BN monolayer films that have large single-crystalline domain sizes, up to -72 μm in edge length, prepared using a folded Cu-foil enclosure. The highly confined growth space and the smooth Cu surface inside the enclosure effectively reduced the precursor feeding rate together and induced a drastic decrease in the nucleation density. The orientation of the as-grown h-BN monolayer was found to be strongly correlated to the crystallographic orientation of the Cu substrate： the Cu （111） face being the best substrate for growing aligned h-BN domains and even single-crystalline monolayers. This is consistent with our density functional theory calculations. The present study offers a practical pathway for growing high-quality h-BN films by deepening our fundamental understanding of the process of their growth by CVD.