DFT study on formaldehyde catalytic oxidation mechanism over Pd(111)/Pd(100) in electroless copper deposition

The study of catalytic mechanisms of palladium-based activators in electroless copper plating is essential for improving coating quality and process efficiency. Many scholars are conducting research on palladium-reduced or palladium activators. However, the mechanism of palladium's role in electroless copper plating remains to be explored, which will greatly help in the development of new activation solutions for electroless copper plating. Based on this, density functional theory (DFT) was used to study the catalytic reaction mechanism of formaldehyde on the main exposed surfaces (111) and (100) of Pd, and the adsorption of each intermediate was determined. Four possible reaction pathways were proposed to elucidate the kinetic feasibility of the target reaction, and the energy barriers and step diagrams of these pathways were systematically calculated. The results show that the most reliable pathway is that HCHO reduces Cu2+ through the transformation pathway of HCHO – CH2(OH)O− – CH2O22− – HCOOH in an alkaline environment. Pd(111) can effectively reduce the activation energy required for the formation of the intermediate CH2O22−, and has better adsorption and catalytic properties than Pd(100). This study aims to provide a theoretical reference for the development of new activation solutions for electroless copper plating.