Synthesis and characterization of platinum supported on surface-modified ordered mesoporous carbons by self-assembly and their electrocatalytic performance towards oxygen reduction reaction

Ordered mesoporous carbons (OMCs) were fabricated by an organic–organic self-assembly process. Surface-modified OMCs were also prepared via the conventional acid-oxidation, H₂O₂ oxidation and 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (AEPTMS) grafted routes. Pt nanoparticles (NPs) supported on OMC (Pt/OMC) and modified OMC (Pt/OMC-H₂SO₄, Pt/OMC-H₂O₂ and Pt/OMC-AEPTMS) were synthesized and characterized by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), transmission electron microscopy (TEM) analysis. It was found that acid-oxidation (H₂SO₄/HNO₃) method led to formation of a much wider Pt distribution with mean particle size of 6.8 nm. Unlike Pt/OMC-H₂SO₄ samples, Pt NPs (ca. 2.0 nm) were supported uniformly on AEPTMS-modified OMC with low electrical conductivity. Among three surface-modified methods, the H₂O₂ treatment method was an easily controllable way for surface modification of OMC which possesses desirable electrical conductivity, well-dispersed and nanosized Pt (ca. 3 nm). Accordingly, the Pt/OMC-H₂O₂ samples were observed to have superior electrocatalytic activity for oxygen reduction reaction as compared to synthesized Pt/OMC, Pt/OMC-H₂SO₄, Pt/OMC-AEPTMS and the commercial electrocatalysts (Pt supported on XC-72).