Low temperature proton exchange membrane fuel cell operation with 1% carbon monoxide in hydrogen

Low temperature proton exchange membrane fuel cells (LT-PEMFC's) are a proven means of direct energy conversion with thermodynamic efficiency two to three times that of the internal combustion engine. LT-PEMFC's currently use commercial Pt electrodes that require ultra-high purity hydrogen containing not more than 0.0001 % CO as a fuel source to prevent deactivation at the anode. While this restriction yields energy with essentially zero carbon tailpipe emissions, the high cost and centralized infrastructure to produce such fuel limits widespread implementation of LT-PEMFC technology. Here we describe the use of unsupported PtBi alloy nanoparticles to permit the use of 1% CO in hydrogen at the anode. Stable LT-PEMFC operation at 30% the power in ultra-high purity hydrogen is obtained at 0.2 A cm −2 . This CO content is comparable to that found in much less expensive synthesis gas and is an order of magnitude higher than is tolerated by any other electrocatalyst. Voltage oscillations typically associated with the Langmuir-Hinshelwood CO electrooxidation mechanism on state-of-the-art CO-resistant PtRu/C electrodes are eliminated. Unlike PtRu/C, a significant fraction of the interfacial potential associated with active sites on PtBi is employed to reposition CO ads on the electrocatalyst surface and is more consistent with the Eley-Rideal mechanism.