Waste-derived nanomaterials: defect engineering, supramolecular assembly, and design rules for sustainable hybrids

• Waste streams serve as intrinsic sources of dopants, defects, and supramolecular sites. • Integrated framework links precursor chemistry, defect engineering, and hybrid design. • Thermochemical, biological, and mechanochemical syntheses enable defect modulation. • Structure–defect–function relationships govern multifunctional material performance. • LCA, TEA, AI-driven defect prediction, and digital twins enable scalable deployment. The conversion of waste feedstocks into functional nanomaterials facilitates sustainable methodologies by transforming discarded biomass, polymers, industrial by-products, and electronic waste into valuable hybrid systems. This review rigorously analyzes the manner in which chemical signatures derived from waste influence defect formation, supramolecular assembly, and hierarchical structuring across nano-, meso-, and macro-scales. A comparative evaluation of thermochemical, biological, and mechanochemical methodologies is presented regarding their effectiveness in modulating defects, dopants, and interfaces that are critical to material performance. Quantitative correlations that connect defect metrics to electrochemical, catalytic, and biomedical functionalities are emphasized, substantiated by case studies and performance matrices. Additionally, the review incorporates life cycle and techno-economic assessments, delineating design principles that reconcile high functionality with environmental sustainability. Innovative tools, such as Artificial Intelligence (AI)-based defect prediction and digital twin modeling, are described as facilitators for scalable production. By reframing waste as a resource rich in design potential, this work outlines a strategic framework for the development of next-generation, sustainable hybrid nanomaterials.