Induction of non-uniform corrosion on the Fe(100) surface by (Fe2O3)n clusters: A DFT study

Iron corrosion in natural environments is strongly influenced by early-stage corrosion products such as (Fe 2 O 3 ) n clusters. Using density functional theory (DFT), we investigated the adsorption and electronic effects of (Fe 2 O 3 ) n clusters with n = 1, 2, and 3 on the Fe(100) surface. All clusters adsorb stably and disrupt surface charge uniformity, generating localized regions of charge depletion that promote anodic dissolution. Concurrently, electron transfer from Fe atoms to the clusters establishes cathodic centres, forming localized anodic–cathodic pairs that accelerate corrosion. These effects intensify with increasing cluster size, with the n = 3 cluster inducing the strongest charge redistribution and lowest reaction energy barriers. Additionally, over-stabilization of OH* intermediates suppress the cathodic oxygen reduction reaction, contributing to asymmetric reactivity. This spatial differentiation initiates non-uniform corrosion, such as pitting. The findings provide atomic-scale insight into corrosion mechanisms and demonstrate the predictive value of DFT in guiding corrosion mitigation strategies. • Stable adsorption of iron oxide clusters: (Fe 2 O 3 ) n clusters (n = 1–3) adsorb strongly on Fe(100), disrupting surface charge uniformity and initiating corrosion processes. • Localized anodic–cathodic pairs accelerate corrosion: Electron transfer from Fe to clusters creates cathodic centres, while charge depletion zones promote anodic dissolution, enhancing corrosion kinetics. • Cluster size amplifies corrosion effects: Larger clusters (n = 3) induce the strongest charge redistribution and lowest energy barriers, intensifying localized corrosion. • Suppression of oxygen reduction reaction: Over-stabilization of OH* intermediates inhibits cathodic ORR, causing asymmetric reactivity and triggering pitting corrosion.