Highly dispersed PtNi nanoparticles modified carbon black as high-performanced electrocatalyst for oxygen reduction in acidic medium

Abstract

• Rational optimization of Ni/C precursor for Pt galvanic replacement. • Regulation on the electronic structure of active site stemmed from PtNi alloys. • PtNi/C shows excellent and stable ORR activity via 4e - pathway in acidic medium. • The mass activity of PtNi/C at 0.8 V is 9.4 times that of commercial Pt/C. Due to the excellent intrinsic activity, platinum-based materials are widely used to produce highly efficient electrocatalysts towards oxygen reduction reactions (ORR), but their ultrahigh price and poor stability severely hinder the mass production and further wide application. Alloying Pt with 3d transition metals through galvanic replacement is an effective way to reduce Pt loading based on the premise of outstanding ORR activity. In this work, to fabricate the optimal precursor for subsequent galvanic replacement, a series of carbon-supported Ni samples were firstly prepared by tuning the Ni loading amount and pyrolysis temperature. Then, the highly dispersed PtNi nanoparticles modified carbon nanohybrid (PtNi/C) with low Pt content of 2.29 wt% can be obtained, which exhibits remarkable and durable ORR activity with E 1/2 of 0.841 V vs. RHE via efficient 4e - ORR process in acidic media. Moreover, it should be emphasized that the as-synthesized PtNi/C behaves the impressively high mass activity of 0.57 A/mg Pt at 0.8 V, which is 9.4 times that of commercial Pt/C. It is confident that our work can offer constructive suggestions for the design and synthesis of high-performanced electrocatalysts fabricated through galvanic replacement method.