Designing effective organic corrosion inhibitor from first-principles modelling

Corrosion of metal remains a major issue to many industries such as utilities, infrastructures, and consumer electronics nowadays. It can cost billions of dollars for maintenance and extending the service life of the applications. Aluminium (Al) is one of the mostly used light-weighted metals in those applications. It is thus important to develop more effective ways to mitigate the corrosion process in Al metal. Imidazole and quinoline are two commonly used organic corrosion inhibitors on Al metal. But the inhibiting mechanism has not been well-understood and compared. More importantly, the effects of chemical functionalization of these molecules on the corrosion inhibiting effectiveness have yet been explored. In this project, we investigated the corrosion inhibiting mechanism of imidazole and quinoline based organic inhibitors using density functional theory (DFT) calculations and aimed to design more effective inhibitors via chemical functionalization with fluoride (F) and hydroxide (OH) on imidazole and quinoline. We found that in general, the organic inhibitors bind stronger to the aluminium oxide (Al2O3) surface than the Al metal surface, attributing to the stronger interactions between the oxygen atoms on the oxide surface and the heteroatoms/functional groups on the inhibitors. More importantly, we found that the OH functionalized imidazole exhibits stronger binding strength to both surfaces as compared to its pristine form, showing an improved corrosion inhibitor for Al. In addition, as a use case study, we investigated the effects of hydrofluoric (HF) acid on aluminium when it is used as a current collector in lithium-ion batteries. We found that the OH functionalized imidazole exhibits stronger affiliation to the HF acid molecule on the oxide surface compared to other inhibitors, showing its potential to protect Al2O3 from acid-attack. Overall, the work predicted that the OH functionalized imidazole is an improved organic corrosion inhibitor for Al.Bachelor of Engineering (Mechanical Engineering