Hierarchical Coassembly of NiMo 3 S 13 /MoS 2 /Ni 3 S 2 on Nickel Foam for Selective Extraction of Ag + over Cu 2 + and Reduction of Ag + to Metallic Ag 0

Through a one-step solvothermal reaction of (NH4)2Mo3S13·H2O and nickel foam (NF), a coassembly of NiMo3S13/MoS2/Ni3S2/NF is fabricated, exhibiting highly selective extraction capability for precious metal silver. Under an initial Ag+ concentration range (C0Ag) of 10–1300 ppm, the NiMo3S13/MoS2/Ni3S2/NF demonstrates extremely high silver removal (>99.9%), realizing an exceptionally large silver sorption capacity (qmAg) of 1456 mg g–1. Notably, a much more rapid Ag sorption rate is achieved, with 10 ppm C0Ag being decreased to 0.079 ppm (79 ppb) within 10 min (Ag removal ∼99.2%). For trace Ag+ (∼1 ppm C0Ag) coexisting with highly concentrated competitive ions of Cu2+ (Cu:Ag molar ratio ∼2241), a large Ag/Cu separation factor (SFAg/Cu) of 684 is reached, showing wonderful separation capacity of Ag+ over Cu2+. The Ni0 (from NF and Ni3S2), Mo4+ (from NiMo3S13 and MoS2), and S22–/S2– in NiMo3S13/MoS2/Ni3S2/NF act as reducing agents to fulfill the reduction of Ag+ to Ag0 crystals with a novel morphology of ultrathin nanosheets. The overwhelmingly high extraction capability for precious metal Ag makes the NiMo3S13/MoS2/Ni3S2/NF a top-tier sorbent. This work offers valuable insights into the design of highly efficient sorbents to trap Ag+ and extract noble Ag0 from complex aqueous solutions or Cu/Ag ore leachates.