Microscopic Insights into Impurity-Modulated Capture of Platinum-Group Metals by Bismuth in Copper Anode Slimes

The efficient recovery of platinum group metals (PGMs) from decoppered anode slimes is essential for sustainable resource management, yet the atomic-level mechanisms underlying their capture remain unclear. Herein, first-principles calculations were employed to elucidate the microscopic interactions by which bismuth acts as a trapping agent for PGMs (Ru, Ir, Pt, Rh, Os, Pd) and to determine the effects of four representative impurities (As, Sb, Pb, Si). The results demonstrate that pristine Bi(001) exhibits strong chemisorption toward all six PGMs, as proved by the large charge transfer, significant electron sharing and pronounced p-d orbital hybridization. Furthermore, these impurities spontaneously incorporate into the Bi(001) surface due to the large binding energy. Crucially, some impurities such as As and Si function as potent surface activators rather than detrimental contaminants. These dopants significantly enhance the PGM binding strength by inducing intense localized charge redistribution and establishing strong orbital hybridizations among the Bi-5d, PGM-d and p orbitals of dopants. Overall, this work provides a theoretical foundation for strategically utilizing the impurities to optimize the recovery of PGMs in complex smelting systems.