Sustainable pulse electrodeposition of copper from cyanide-free alkaline baths enables high-performance and additive-free industrial coatings

Cyanide-free alkaline copper electrodeposition represents a sustainable alternative to traditional hazardous baths, yet direct current (DC) methods often suffer from severe non-uniformity and poor aesthetic quality. This study investigates pulse current (PC) electrodeposition as an efficient strategy to overcome these limitations. Results show that, in cyanide-free baths, PC deposition improves coating homogeneity, reduces grain size and increases gloss to values exceeding 1000 compared with DC (171). This dramatic aesthetic and structural enhancement stems from the high peak current densities during pulse times, which generate elevated cathodic overpotentials that strongly promote high crystal nucleation rates over grain growth. Furthermore, PC parameters enable effective additive-free deposition, avoiding the local coating burning and decomposition caused by organic additives under high instantaneous current densities. When applied to complex 3D fashion accessories, optimized PC deposition achieved exceptional thickness uniformity, reducing standard deviation from ± 3.7 μm (DC) to just ± 0.4 μm. These findings demonstrate that tailored PC electrodeposition provides a green, high-performance and additive-free solution for decorative industrial plating.