Electrochemical metal nucleation and growth mechanism from metal nitrate-L-serine deep eutectic solvent

Electrodeposited nickel, cobalt, and their alloys are critical for applications including energy storage, electrocatalysis and magnetic devices . Traditional aqueous electrodeposition suffers from hydrogen evolution , causing embrittlement , while deep eutectic solvents (DES) offer a promising alternative owing to their low water activity. Here, amino acid-metal nitrate DES (Ni(NO 3 ) 2 and/or Co(NO 3 ) 2 -L‑serine) are introduced, and the electrochemical nucleation and growth mechanisms of Ni, Co, and their alloys are investigated. Cyclic voltammetry and potentiostatic transient analyses reveal potential-dependent nucleation and growth behavior . Electrodeposition of Ni from Ni(NO 3 ) 2 /L‑serine DES exhibits a two-stage nucleation and growth behavior. The electrodeposition of Co from Co(NO 3 ) 2 /L‑serine DES follows a three-dimensional progressive nucleation mechanism. New models integrating proton reduction and adsorption with Scharifker-Mostany model for monometallic deposition and with Scharifker model for alloy deposition are proposed to interpret potentiostatic current transient behavior. The deposits are characterized by X-ray diffraction and scanning electron microscopy and the crystalline metal phases are confirmed.