Uniform Pt@Pd nanocrystals supported on N-doped reduced graphene oxide as catalysts for effective reduction of highly toxic chromium(VI)

Abstract In this work, we developed a facile one-pot co-reduction method for fabrication of spherical porous Pt@ultra-thin Pd skin core-shell nanocrystals supported on N-doped reduced graphene oxide (Pt@Pd NCs/N-rGO). Trajenta (Tra), a kind of dipeptidyl peptidase-4 inhibitors for treatment of diabetes, served as a new structure-directing agent for Pt@Pd NCs and N-doping resource for rGO via π-π stacking interactions. The product was mainly characterized by microscopic analysis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetry (TGA), Raman and Fourier transform infrared (FT-IR) spectroscopy, and the formation mechanism was discussed in some detail. By taking formic acid as the reductant, the Pt@Pd NCs/N-rGO nanocomposite showed significantly enhanced catalytic ability and improved repeatability for the reduction of highly toxic hexavalent chromium (Cr(VI)) compared with commercial Pt/C (20  wt %) and Pd/C (20  wt %).