Specific Recovery and In Situ Reduction of Precious Metals from Waste To Create MOF Composites with Immobilized Nanoclusters

Incorporation of active metal (especially precious metal) nanocomponents into metal–organic frameworks (MOFs) could capacitate MOFs with enhanced or new properties for innovative industrial applications. Despite increasing numbers of reports of precious metal nanoparticles/MOFs, developing such composites with low cost and high metal loading is still highly desirable. Herein, we demonstrated a novel and facile method to convert precious metal waste to wealth via using thiourea modified MOFs of UiO-66-TU as a proof of principle to recover and immobilize precious metals. The new MOFs exhibited excellent selectivity which allowed for precious metals to be isolated from the waste electronic and electrical equipment (WEEE), which commonly contain different metal species. UiO-66-TU extracts a representative precious metal of Au effectively in a wide pH range, and the maximum Au adsorption capacity could approach 326 mg g–1. Through a simple reduction treatment, the adsorbed Au ions could be converted to well-dispersed Au nanoclusters (NCs, size below 1.8 nm) embedded in the MOFs, resulting in useful Au NCs/MOF composites. The merits of low cost and considerable Au loading, combined with the good stability of the Zr based MOFs, make the currently prepared Au NCs/UiO-66-TU composites potentially promising for various applications.