Component self-assembly for reciprocal urban mining

Urban mines—stockpiles of materials in discarded waste—include various metals, oxides, polymers and halogens with diverse implications in terms of materials sustainability, which are reflected in different environmental–economic–efficiency trade-offs when recycling them. Here we leverage the diverse composition of urban mines to develop ‘reciprocal recycling’—a self-assembly strategy that uses urban mine components to support their own recycling to ultimately activate sustainable urban mining. We screened tens of physicochemical componential interactions available for multimetal co-recovery, halogenated pollutants elimination and polymer conversion. Self-assembly prototypes with four fundamental componential interactions were presented for reciprocal recycling of representative urban mines. Under the guidance of revealed physicochemical interaction mechanisms, the reciprocal recycling process design enabled >96% recovery of copper–platinum–palladium–rhodium, >99% suppression of brominated pollutants and mediated epoxy resin conversion. The self-assembly strategy showcased joint environmental–economic–efficiency benefits and high flexibility, paving the way to sustainable urban mining and improving material circularity. Urban mining is crucial for improving the sustainability of materials cycle but hindered by the complexity of urban mine composition. Here the authors develop a self-assembly strategy that takes advantage of the composition diversity of urban mines to achieve sustainable reciprocal urban mining.