Piezoelectric catalysis for selective recovery of precious metals (Cu and Au) from waste CPUs

This study addresses the technical challenges of traditional processes for precious metal recovery from electronic waste, including high energy consumption, severe pollution, and the use of highly corrosive reagents. We innovatively propose a green recovery strategy based on piezoelectric catalysis. By combining the compositional characteristics of electronic waste (Cu > 80 wt%, Au 0.1–0.5 wt%) with the hard-soft acid-base (HSAB) theory, we developed a BOC-NH₄Cl-CH₃CN-H₂O catalytic system. This system achieves efficient dissolution of copper and gold (1334 mg h −1 ·g-cat −1 and 2.7 mg h −1 ·g-cat −1 , respectively) through an oxidation-coordination mechanism, with dissolution rates reaching 99.8% and 95.5% in simulated systems and enrichment purity exceeding 99%. Based on the experimental data, it is proposed that under piezocatalysis, acetonitrile is oxidized to acetamide, which then synergistically coordinates with NH₃/Cl − to form stable coordination products (with binding energies of E_Cu = −4.034 eV and E_Au = −2.993 eV, respectively). This process may serve as a key mechanism responsible for the significant enhancement of metal dissolution. Due to the lower oxidation potential of Cu ( E°  = 0.34 V) compared to Au ( E°  = 1.5 V), the system exhibits a “high‑copper, low-gold” selective dissolution characteristic that aligns well with waste composition. This technology provides an efficient and environmentally friendly solution for metal recovery from electronic waste.