Block copolymer reduces, protects and mediates oriented growth into nano/submicron branched platinum

Abstract

New nano/submicron branched platinum (B-Pt) was readily synthesized by auto-reduction reflux of H₂PtCl₆ solution mixed with poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic F127, PEO₁₀₀PPO₆₅PEO₁₀₀). The as-prepared B-Pt shows many interconnected fractal twigs with the diameter of each branch at nano-level though the whole B-Pt array is relatively large at submicron size. High resolution transmission electron microscopy (HRTEM) shows that the B-Pt generally exposed (111) planes and possesses a high density of edges and corners, widespread lattice distortions, step and suspension atoms, which are all beneficial for electrocatalysis. Electrochemical tests, comparing the kinetic current, further confirmed that the oxygen reduction reaction (ORR) activity of the B-Pt was better than that of current commercial Pt black and Pt/C catalysts. The copolymer serves as reducing, protecting and orienting agent at the same time and the growth mechanism of B-Pt is described in detail.