Surface science perspectives on eco-friendly corrosion inhibitors

The science of metallic degradation and its control have developed significantly over the past decades. Beginning with traditional corrosion inhibitors such as chromates, nitrates and phosphates which are well-known for their effectiveness and environmental hazards, the field has recorded great progress with the development and implementation of safer alternatives. This recent shift is premised on global regulatory measures, increasing environmental campaigns, promotion of green chemistry ideals and industrial demands. Latest advances in the field now promote the use of eco-friendly materials like bio-based ionic liquids, biopolymers, plant extracts and biosurfactants for corrosion protection. This review captures the surface and interfacial activities of these sustainable corrosion inhibitors which are extensively explored using cutting-edge experimental and computational techniques. Electrochemical insights, together with corrosion inhibition efficiencies ranging from 80 to 99 % for typical eco-friendly inhibitors have been obtained using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. Modern analytical techniques including X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electron microscopy (SEM) have resulted in structural and mechanistic insights at the electrode/electrolyte interface. Recent advancements in molecular modelling and machine learning have further enhanced the understanding of inhibitor-metal interactions and rational design of eco-friendly inhibitors. Overall, this review succinctly highlights recent progress in eco-friendly inhibition approach, outlines green chemistry metrics, identifies key challenges and proposes future research directions to accelerate industrial implementation. • The perspectives of eco-friendly corrosion inhibitors were discussed. • The interfacial mechanism of eco-friendly corrosion inhibitors was highlighted. • The key factors and green metrics of eco-friendly corrosion inhibitors were discussed. • The mini-review provides a roadmap for next-generation materials for corrosion control.