Ni₂P Entwined by Graphite Layers as a Low-Pt Electrocatalyst in Acidic Media for Oxygen Reduction

A simple and feasible strategy was reported to construct Ni₂P nanostructures entwined by graphite layers (Ni₂P/GC). In this process, a commercial amino phosphonic acid chelating resin was adopted as both the phosphorus and carbon resources. Then, Ni²⁺ was introduced into the resin framework via ionic exchange and chelation to form a resin-Ni²⁺ precursor. After carbonization, the highly dispersed Ni₂P particles, coupled with thin graphite layers, were simultaneously synthesized in situ. A ternary 7.5% Pt-Ni₂P/GC catalyst was further obtained by loading 7.5 wt % Pt on Ni₂P/GC. For the oxygen reduction reaction in acidic media, the 7.5% Pt-Ni₂P/GC catalyst exhibited even more positive onset (1.03 V) and half-wave (0.93 V) potentials, as well as a rather higher mass activity of 565.3 mA mg_Pt^-1 and a better long-term stability than those of the commercial 20% Pt/C (JM) electrocatalyst. The improved reaction kinetics is mainly attributed to the synergistic effect between Pt and Ni₂P/GC. This work not only provides a method for the synthesis of phosphides but also gives insight into the synergy between Pt and Ni₂P, which is helpful for the development of more low-Pt catalysts in acidic media.