Graphene Based Copper‐Nickel Bimetal Nanocomposite: Magnetically Separable Catalyst for Reducing Hexavalent Chromium

Graphene based copper‐nickel bimetal nanocomposite (Cu 3 Ni 2 ‐rGO) was prepared via a one‐step solvothermal procedure, in which Ni(OH) 2 and Cu(OH) 2 were used as precursors. Structural characterization confirms that the as‐prepared Cu 3 Ni 2 ‐rGO nanocomposite is composed of Cu 3 Ni 2 nanoparticles in the size range of 20–100 nm and the reduced graphene oxide (rGO) sheets. Benefiting from the combination of Cu 3 Ni 2 and rGO, the Cu 3 Ni 2 ‐rGO nanocomposite exhibits excellent catalytic performance on reducing highly toxic Cr(VI) at room temperature. The reduction of Cr(VI) (40 mL, 100 mg L −1 ) can be completed within 6 min using Cu 3 Ni 2 ‐rGO nanocomposite as the catalyst, which is much more efficient than using monometallic nanocomposite containing only Cu or Ni. Moreover, Cu 3 Ni 2 ‐rGO nanocomposite can be magnetically separated, which enables effective recycle. Besides, Cu 3 Ni 2 ‐rGO shows good cycling stability.