Recovery-Induced Spatial Engineering of Au/MXene Nanoarchitectures for Direct Ion-to-Electrode Conversion

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Abstract
Creating direct pathways that transform dissolved metal waste into functional architecture is central to sustainable nanomanufacturing and circular materials design. Here, we report a redox-driven strategy for the direct conversion of gold (Au) ions from electronic waste into spatially organized Au/MXene nanoarchitectures and electrocatalytic membranes. Ti3C2Tx MXene nanosheets exhibit an Au uptake capacity of 3720 mg g–1 at 1 ppm, together with high selectivity in the presence of excess competing metal ions. Mechanistic studies reveal that the Au capture is coupled with spontaneous interfacial redox conversion, where ∼91% of Au(III) ions are reduced in situ into metallic Au nanoparticles on the MXene surface. Importantly, performing the recovery process in a dispersed colloidal state enables recovery-induced interlayer assembly, producing homogeneous Au distributions throughout the MXene framework after vacuum-assisted membrane formation. In contrast to surface-confined deposition in conventional filtration architectures, the interlayer nanoarchitecture preserves ion-transport pathways and maximizes catalytic accessibility. We further show that ultratrace Au concentrations promote the formation of highly dispersed confined Au domains, enabling efficient electrocatalytic membranes despite substantially lower gold loading. The resulting membranes function directly as flexible binder-free electrodes without additional refining, metal stripping, or catalyst deposition steps. This work establishes a recovery-as-fabrication strategy in which dissolved metal ions are directly transformed into functional nanoarchitectures through coupled redox reduction, confined nucleation, and interlayer assembly.
Funding Information
  • Guangdong Provincial Introduction of Innovative Research and Development Team (2023ZT10L039)
  • Royal Society (RSRP\R\190000)
  • Ministry of Education - Singapore (EDUNC-33-18-279-V12)

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