Targeted Passivation of High-Activity Cu (220) Facet for Enhanced Oxidation Resistance in Cu Powders

Copper (Cu) powder, valued for its exceptional conductivity and low cost. However, their applications suffer from severe oxidation. Existing organic modification strategies overlook the intrinsic surface energy anisotropy of Cu, inadequately suppressing initial oxidation at high-active sites and consequently poor oxidation resistance. To address this limitation, this work proposes a priority targeted passivation of high-activity facets strategy. This approach recognizes that high-activity sites on Cu surfaces serve as primary triggers for oxidation reactions, by preferentially blocking O 2 dissociation at these active sites, oxidation can be substantially suppressed. Three environmentally friendly modifiers — stearic acid (SA), oleic acid (OA), and 1-dodecanethiol (1-D) were screened for surface modification. Systematically investigated how their facet-selective adsorption regulates oxidation pathways in Cu particles. While OA preferentially adsorb onto high-activity Cu (220) facets, effectively inhibiting O 2 dissociation at these critical sites and suppressing oxidation at its source. OA-modified Cu powder preserved 63.40 % metallic Cu after 180°C/8h sintering and remained unoxidized after 180 days in air exposure, demonstrating exceptional antioxidation performance. This study establishes that prioritized passivation of highly energy facets is essential for enhancing the oxidation resistance of Cu powders.