Synthesis of highly stable and methanol-tolerant electrocatalyst for oxygen reduction: Co supporting on N-doped-C hybridized TiO2

The currently used carbon supported Pt or Pt alloy catalysts for cathodic oxygen reduction reaction (ORR) suffer from prohibitive cost as well as limited productivity of Pt, carbon-support corrosion, and methanol poisoning. Here we report a one-pot heat treatment for synthesis of Co supporting on N-doped-C (C-N) hybridized TiO2 catalyst. For the first time, TiO2 is used as the predominant content in C-based ORR catalyst. Fiber-like polyaniline (PANI) is introduced as a C-N precursor and also acts as a good template for growing TiO2 crystals. During the following one-pot heat treatment, the metallic Co particles are in situ growing on the carbonized TiO2/PANI support. The influences of PANI proportion, calcination temperature, and Co incorporation on the ORR catalytic performance are systematically investigated. The optimal Co/TiO2/C-N catalyst shows higher stability and methanol-tolerance than commercial Pt/C or Co/C-N catalyst with comparable activity. The remarkable enhancement of stability is mainly ascribed to the following two reasons: (1) the excellent chemical stability of rutile TiO2; (2) the strong interactions of "TiO2-PANI coupling" and "metal-support coupling". Thus, TiO2/C-N appears to be a promising substitute for carbon materials when supporting metal or metal oxide catalyst for PEMFC application in terms of electrochemical stability. (C) 2015 Elsevier Ltd. All rights reserved.