Studies On The Stability Of Catalyst Based On Conductive Nano-Ceramic Supports For PEMFC

Pt-based catalysts are usually employed as anode and cathode catalysts in proton exchange membrane fuel cell (PEMFC). However, carbon supports in PEMFCs are under strongly oxidizing conditions:high water content, low pH (<1), high temperature (50-90℃), high potential (0.6-1.2 V versus Reversible Hydrogen Electrode, RHE), high oxygen concentration can be oxidized to CO or CO2. The insufficient stability of catalysts remains a major obstacle to the widespread commercialization of PEMFCs. The homogeneously dispersed Pt nanoparticles were deposited on the surface of ceramic support using an ethylene glycol reduction method. The structure, performance and durability of the prepared catalysts were characterized by TEM, XRD, CV and ADT. The experimental results and conclusions are summarized as following:1) nano-SiC ceramic and ZrO2-C have almost no change in the redox region after oxidation treatment for 48 h, which means there are negligible surface oxides. Contrarily, there are visible current peaks in the redox region for Vulcan XC-72, resulting from the surface oxide formation due to the hydroquinone-quinone (HQ-Q) redox couple on the carbon black surface These results indicate that nano-SiC and ZrO2-C are more resistant to electrochemical oxidation than Vulcan XC-72;2) The HRTEM images demonstrate that Pt nanoparticles are successfully deposited and homogeneously dispersed on the novel supports with a particle size of-3 nm, indicating that the introduced ceramic as novel support of Pt nanoparticles is extraordinarily successful;3) The CV results show our catalysts have good catalytic activity, The ECSA of Pt/SiC/C and Pt/ZrO2-C catalysts are close to the traditional Pt/C, and the ECSA of Pt/B4C is higher than Pt/C with a improved CO-tolerant performance;4) Based on ADT and HRTEM, the electrochemical stability of the novel catalysts were remarkably enhanced compared with the Pt/C catalysts, after ADT, a lot of Pt nanoparticles detached from the surface of carbon, in contrast, slight agglomeration of Pt particles is observed for the ceramic support, there is still a large number of Pt particles remaining on the ceramic surfaces.This study supplies a possibility to prepare an advanced catalyst with high electrocatalytic performance and stability by using nano ceramic materials as supports.