An aqueous solution synthesis method was used to synthesize a Pt-Ni/GNs composite containing trace amounts of Ni species by the aid of self-etching or acid-etching process. Its component structure and morphology were characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) and Raman spectra, etc. The obvious cracked Pt-Ni nanoclusters can be found in Pt-Ni (trace)/GNs which contains only trace Ni species. Electrochemical experiments indicate that Pt-Ni (trace)/GNs exhibits bi-functional electrocatalytic performance for MOR and ORR with the mass activity of 1009.98 mA mg(-1) and 157.7 mA mg(-1), respectively, which is superior to commercial Pt-Ru/C-JM. It is proven that the trace Ni species contribute to the enhanced electrocatalytic performance of the Pt-Ni/GNs composite. (C) 2019 Elsevier Inc. All rights reserved.