A Study on the Effect of Electrodeposition Parameters on the Morphology of Porous Nickel Electrodeposits

In this study, the electrodeposition of nickel foam by dynamic hydrogen bubble-template method is optimized, and the effects of key deposition parameters (applied voltage and deposition time) and bath composition (concentration of Ni²⁺, pH of the bath, and roles of Cl⁻ and SO₄²⁻ ions) on pore size, distribution, and morphology and crystal structure are studied. Nickel deposit from 0.1 M NiCl₂ bath concentration is able to produce the honeycomb-like structure with regular-sized holes. Honeycomb-like structure with cauliflower morphology is deposited at higher applied voltages of 7, 8, and 9 V; and a critical time (>3 minutes) is required for the development of the foamy structure. Compressive residual stresses are developed in the porous electrodeposits after 30 seconds of deposition time (−189.0 MPa), and the nature of the residual stress remains compressive upto 10 minutes of deposition time (−1098.6 MPa). Effect of pH is more pronounced in a chloride bath compared with a sulfate bath. The increasing nature of pore size in nickel electrodeposits plated from a chloride bath (varying from 21 to 48 μm), and the constant pore size (in the range of 22 to 24 μm) in deposits plated from a sulfate bath, can be ascribed to the striking difference in the magnitude of the corresponding current–time profiles.