Mesoporous Chromium Nitride as High Performance Catalyst Support for Methanol Electrooxidation

Abstract

A simple process for preparing mesoporous chromium nitride (CrN) by the ammonolysis of a bulk ternary oxide (K2Cr2O7) is reported. The products were characterized by Rietveld refinement of powder X-ray diffraction patterns, scanning electron microscopy (SEM), and nitrogen adsorption/desorption analysis. Pore sizes ranging from 10 to 20 nm are easily accessible. The conductivity of mesoporous CrN powder compressed at 35 bar is 54 S/cm. A Pt/CrN catalyst prepared from the mesoporous CrN shows a negative onset potential for methanol electrooxidation (0.20 V vs SCE) similar to that of Pt/C (0.22 V vs SCE). The electrochemically active specific surface area (ECSA) of the Pt/CrN catalyst (82 m2/g) was only slightly higher than that of Pt/C (75 m2/g). More importantly, the Pt/CrN catalyst demonstrates high tolerance to corrosion and is a candidate to replace carbon black, which is known to corrode under high potentials, as a support for fuel cell catalysts. This work provides an efficient method for preparing mesoporous metal nitrides that are promising supports for the oxidation of small organic molecules in fuel cells.