Role of complex formation in mass transport during nickel electrodeposition from low-concentration formate-chloride electrolytes

Nickel electrodeposition from 0.2 M formate-chloride solutions is studied. Depending on electrolyte pH(0), the highest current density of the electrod eposition of compact nickel deposits varies from 3 (pH(0) 3.5) to 40 A dm(- 2) (pH(0) 2.0). With the current efficiency for nickel taken into account, this corresponds to nickel deposition rates of 3 to 25 A dM(-2). One of the reasons for the high permissible current densities is good buffer properti es of the electrolyte. Computer calculations show that the considerable acc eleration of the nickel electrodeposition is due to mass transport accelera ted by the formation of complex [NiL](+) cations. The complex formation als o affects the intensity of interaction between nickel and hydrogen ions tra nsported to the cathode. The current by nickel increases due to the partici pation of formic acid molecules in the hydrogen evolution.