A new route for preparing nanoporous Cu–Zn–Ni–Co alloy by electrodeposition and dealloying: Application as electrocatalysts for water reduction

Nanoporous Cu–Zn–Ni–Co alloys have been prepared on Cu foils by a two-step electrodeposition mechanism in ethylammonium nitrate (EAN), a protic ionic liquid, and ethaline, a deep eutectic solvent (DES). A porous alloy was then produced using a dealloying step. The physicochemical properties of ethaline containing Ni 2+ , Co 2+ , and Zn 2+ salts were firstly investigated. The two-step electrodeposition process for the preparation and dealloying of Cu–Zn–Ni–Co alloys was then discussed. In the first step, cobalt was deposited on copper in pure EAN. Zinc and nickel were subsequently co-electrodeposited in ethaline to produce a Cu–Zn–Ni–Co alloy after further heat treatment. Nanoporous alloys were prepared by electrochemical and chemical dealloying to obtain different electrocatalytic properties for the hydrogen evolution reaction (HER). In comparison to the initial non-porous alloy, the HER performance has been markedly enhanced, with an HER potential reaching as low as −0.067 V/RHE. The novel approach of preparing nanoporous Cu–Zn–Ni–Co alloys by electrodeposition in ionic media, followed by dealloying, represents an efficient methodology for practical applications in electrocatalysis, including water splitting. • Preparation of quaternary alloys (Cu–Ni–Zn–Co) through electrodeposition and heat treatment. • Nanoporous alloy structure controlled through chemical or electrochemical dealloying. • Ni–Cu–Co-based alloys with a uniform nanopores distribution are highly effective electrocatalysts.