A carbon-promoted galvanic replacement method to synthesize efficient PdNi nanoalloy catalyst.

[Display omitted] • A new method to synthesize PdNi, PdCu, and PdFe nanoalloy was proposed. • The Pd based nanoalloy was prepared through a carbon promoting method. • Carbon doping significantly accelerates the displacement rate of nickel. • This catalyst exhibited excellent catalytic performance for pollution treatment. • This catalyst showed high stability in the flow test. PdNi nanoalloy catalysts were prepared by a carbon-promoted galvanic replacement method. Characterizations and control experiments show the increased replacement rate of metal Ni with Pd2+ ion can be attributed to the higher electrode potential and smaller crystalline sizes caused by carbon doping. Introduction of carbon (C) into Ni particles not only accelerates the formation process of PdNi nanoalloys, but also enables C atoms to successfully enter the lattice interstices of PdNi nanoalloys. C regulates the surface electronic properties of PdNi nanoalloys by the electron transfer between different elements and improves their activity. The PdNi@C-650 exhibits extraordinary activity and long-term stability for hydrogenation reduction of hexavalent chromium (Cr (VI)) and hydrodechlorination of chlorophenols in comparison with PdNi/CNTs (carbon nanotubes) and commercial Pd/C. Density functional theory calculations together with investigations of mechanism reveal that the high electron-deficient PdNi nanoalloys from the redistribution of electron between Ni, Pd and C of the PdNi@C-650 promote the surface adsorption of substrate molecules and H 2 , which accordingly enhances the hydrogenation activity. This study brings a new method for the design and preparation of high active noble metal nanoalloy. [ABSTRACT FROM AUTHOR]