Interfacial regulation mechanism of polyacrylamide and thiourea in zinc electrodeposition

Zinc electrodeposition is widely employed in metal protection, electrochemical energy systems, and electronic manufacturing. However, conventional plating systems often suffer from dendritic growth, coarse grains, and poor corrosion resistance, significantly limiting their performance. This study systematically examined the regulatory effects of two representative functional organic additives, polyacrylamide (PAM) and thiourea (TU), on the process of zinc electrodeposition in a weakly acidic ZnSO₄-based electrolyte. By optimizing plating parameters (ZnSO₄ concentration, current density, and pH) and introducing varying concentrations of PAM and TU, the impact on deposition behavior and coating performance was evaluated using electrochemical measurements, surface morphology characterization, and contact angle analysis. Furthermore, density functional theory (DFT) and molecular dynamics (MD) simulations were employed to elucidate the interfacial adsorption behavior and electronic structure characteristics of PAM and TU on the Zn surface. This work clarifies the molecular-level mechanisms of additive-regulated zinc deposition and highlights the pivotal role of quantum chemical calculations in additive screening. The findings provide theoretical guidance and practical insight for the rational design and optimization of functional additives in electrodeposition systems.