Water based electrolyzers offer a promising approach for generating hydrogen gas for renewable energy storage. 3M's nanostructured thin film (NSTF) catalyst technology platform has been shown to significantly reduce many of the performance, cost and durability barriers standing in the way of H 2 /air PEM fuel cells for vehicles. In this paper we describe results from the first evaluations of low loaded NSTF catalysts in H 2 /O 2 electrolyzers at Proton OnSite and Giner, Inc. Over two dozen membrane electrode assemblies comprising nine different NSTF catalyst types were tested in 11 short stack durability tests at Proton OnSite and 14 performance tests in 50 cm 2 single cells at Giner Electrochemical Systems. NSTF catalyst alloys of Pt 68 Co 29 Mn 3 , Pt 50 Ir 50 and Pt 50 Ir 25 Ru 25 , with Pt loadings in the range of 0.1 to 0.2 mg/cm 2 , were investigated for beginning-of-life performance and durability up to 4000 hours as both electrolyzer cathodes and anodes. Catalyst composition, deposition and process conditions were found to be important for meeting the performance of standard PGM blacks on electrolyzer anodes while using only 10% as much PGM catalyst. Analyses of MEA's after the durability tests by multiple techniques document changes in catalyst alloy composition, loading, crystallite structure and support stability.Pure pressurized hydrogen gas offers a convenient and predictable means for storing and transporting convertible energy from renewable or other energy sources for powering fuel cells for vehicle, portable and back-up power applications. Renewable energy sources such as wind and solar will require large, efficient and versatile energy storage means for load leveling over wide periods of time covering seconds to days for which electrochemical storage means offer many advantages. Regenerative fuel cells and H 2 /O 2 electrolyzers used for energy storage are key examples. Water based electrolyzers with higher heating value voltage efficiencies of 75% are projected to be able to produce H 2 in the $3-$4/kg range, competitive with current gasoline prices, at reasonable electricity costs on the order of $0.05/kW-Hr. [1][2][3][4] Proton exchange membrane (PEM) based water electrolyzers offer a promising pathway to efficient hydrogen production because of a small installation footprint, ease of handling the solid polymer electrolyte and ability to generate high pressure hydrogen with only deionized water and electricity as inputs. Commercial PEM electrolyzer costs based on current technology are excessive due both to low volume (batch) system assembly and high stack component material costs. However, the electrolyzer stacks and their internal components, viz. separator plates, PEM's and catalysts have cost factors that could benefit significantly from the technology improvements that PEM fuel cell development has enabled over the past decade or more. With respect to the electrocatalysts, current commercial PEM electrolyzers use 2 mg/cm 2 or more of precious group metals (PGM) on their anodes (oxygen ev...

Two series of high molecular weight disulfonated poly(arylene ether sulfone) random copolymers were synthesized as proton exchange membranes for high-temperature water electrolyzers. These copolymers differ based on the position of the ether bonds on the aromatic rings. One series is comprised of fully para-substituted hydroquinone comonomer, and the other series incorporated 25 mol % of a meta-substituted comonomer resorcinol and 75 mol % hydroquinone. The influence of the substitution position on water uptake and electrochemical properties of the membranes were investigated and compared to that of the state-of-the-art membrane Nafion. The mechanical properties of the membranes were measured for the first time in fully hydrated conditions at ambient and elevated temperatures. Submerged in water, these hydrocarbon-based copolymers had moduli an order of magnitude higher than Nafion. Selected copolymers of each series showed dramatically increased proton conductivities at elevated temperature in fully hydrated conditions, while their H gas permeabilities were well controlled over a wide range of temperatures. These improved properties were attributed to the high glass transition temperatures of the disulfonated poly(arylene ether sulfone)s.

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