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Attractive attributes of carbon nanotubes (CNTs), which include high aspect ratio, excellent electrical and thermal conductivity, high melting point, and longer lifetime, have made this one-dimensional material a promising candidate for next-generation field emitters. In the present work, CNTs were grown directly on copper foil, copper foam, nickel foil and nickel foam through chemical vapor deposition. A comparison between CNT-based two-dimensional emitters, i.e. CNTs synthesized on copper and nickel foils, CNT-based three-dimensional (3D) emitters, i.e. CNTs developed on foams of copper and nickel, have been demonstrated. We observed that CNTs on foams exhibited better field emission compared to CNTs synthesized on foils. This is due to the multistage structure of the 3D foams which provides high surface area for CNT growth and hence enhanced field emission response. In the present work, a CNT sample prepared on nickel foam was observed to exhibit better field emission response compared to the other samples synthesized in the present study. This particular sample demonstrated a very low turn-on field of 0.93 V/lm, excellent field enhancement factor of 13,343 and good stability of electron emission.

The present investigation is aimed to find a thread between various surface textures of polycrystalline Cu−Ni alloys, in cold-rolled and annealed conditions, and the nature of graphene, grown by the chemical vapor deposition (CVD) method, on these substrates. High-quality graphene grown on Cu−Ni alloys was transferred to various nanostructures, such as CuO nanorods and carbon nanotubes, for field emission application. In this work, , and 63Cu−37Ni) alloy buttons were prepared by arc melting, and texture in the samples were engineered by cold rolling (plastic deformation) and annealing (recrystallization) processes. Study of surface texture by X-ray method demonstrates characteristically different deformation and recrystallization texture components, compared to conventional rolling and annealing textures. The evolution of texture has been explained based on the effects of surface friction, shear stress, and addition of Ni. Unusual appearance of {111} orientations, though less in volume, after annealing at 1000 °C, was observed in Cu−Ni alloys through the suppression of cube texture component. The underlying deformation and recrystallization mechanisms are explained through the changes in strain hardening, extended recovery, and continuous recrystallization effects. The effects of Ni content are correlated with the number of graphene layers, while an increase in the fraction of {111} orientations could be linked with defect density in graphene layers. Results of the present study will be motivating for selection of various polycrystalline Cu−Ni alloys, with different surface textures, for controlling quality of graphene, synthesized by the chemical vapor deposition method.