Herein, highly branched Pt@Ag core-shell nanoparticles (Pt@Ag NPs) were fabricated by a facile one-pot wet-chemical approach, where poly(ethyleneimine) (PEI) served as structure-directing and capping agents. Their structure, morphology and composition were mainly characterized by a set of techniques. And their growth mechanism was discussed in some detail. The prepared catalyst exhibited remarkable enhancement in catalytic activity of 4-nitrophenol (4-NP) reduction as a proof-of-concept application, surpassing commercial Pt black and home-made Ag NPs catalysts. Also, the as-obtained catalyst showed superior stability without sacrificing the catalytic activity. These observations endow the catalyst possibility for practical applications in nitrophenols environmental remediation. (C) 2018 Elsevier Inc. All rights reserved.