Effect of multifunctional (NH4)2SO4 and co-deposition factors on porous copper film

Abstract

In this study, porous copper film was prepared by a co-deposition process, which used (NH4)2SO4, a hydrogen source, as dynamic templates. To improve the morphology of porous copper film, sodium citrate was added into the base co-deposition solution as a chemical additive. The phase composition of co-deposited porous copper film was examined by X-ray diffractometer (XRD), while its morphology and nanostructure features were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The porous copper films with earhead-like nanodendrites were synthesized in the base deposition solution by the addition of (NH4)2SO4 which served as an appropriate hydrogen source and suppressed both copper deposition and hydrogen bubbles coalescence. Meanwhile, the porous copper film obtained from the optimized solution containing (NH4)2SO4 and sodium citrate displayed better morphology and structure features. The effect mechanism of (NH4)2SO4 and sodium citrate on the morphology and nanostructure of porous copper film at a 3.0 A cm-2 current density was discussed. Moreover, the effects of CuSO4 concentration and co-deposition current density on porous copper films were respectively investigated. The results demonstrated that the pore size and wall thickness would remarkably increase while the CuSO4 concentration increased. Besides, the porous copper structure started to appear with the walls becoming denser when co-deposition current density increased.