Asian Journal of Applied Chemistry Research

Nanocomposites are increasingly designed to perform more than one interfacial function, yet corrosion protection and wastewater treatment have largely developed as separate materials-engineering domains. This critical narrative review examines the chemistry that connects and, in some cases, places these functions in tension. Literature published from 2010 to 5 July 2026 was evaluated, with selected earlier conceptual evidence considered where necessary. Particular attention was given to graphene and graphene oxide hybrids, conducting-polymer composites, layered double hydroxides and nanoclays, metal-organic frameworks, MXenes, semiconductor heterojunctions, and emerging bio-derived or mineral nanocomposites. Across corrosion protection, effective performance depends on suppressing electrolyte transport, strengthening interfaces, promoting passivation, and enabling controlled inhibitor release or defect response. In wastewater treatment, the same families of materials are exploited for adsorption, photocatalysis, membrane separation, contaminant transformation, and recoverable reactive interfaces. The comparison reveals that multifunctionality is governed less by the nominal identity of the nanofiller than by interfacial accessibility, charge-transfer pathways, defect structure, wettability, porosity, immobilisation and environmental stability. Several properties are intrinsically ambivalent: conductivity can accelerate catalytic electron transfer but promote galvanic corrosion; high porosity can increase sorption or inhibitor storage while increasing electrolyte permeability; oxidation can degrade some two-dimensional barriers yet create useful adsorption or catalytic sites; and strong hydrophilicity assists aqueous treatment while undermining moisture exclusion in protective coatings. A small group of genuinely cross-functional studies demonstrates that corrosion resistance can coexist with adsorption, photocatalysis, antibacterial activity or antifouling, but most evidence remains laboratory-scale and function-specific. The field therefore requires hierarchical and compartmentalised designs, longer-duration and real-matrix testing, rigorous release and regeneration assessment, and performance metrics that treat durability, secondary pollution and recoverability as co-equal design criteria. This cross-domain synthesis provides a materials-chemistry framework for designing nanocomposites whose multiple functions remain compatible throughout service rather than merely coexisting in initial laboratory tests.