Proton transport for fuel cells

No abstract

A Comprehensive Study of an Acid-Based Reversible H2-Br2 Fuel Cell System

The regenerative H2-Br2 fuel cell has been a subject of notable interest and is considered as one of the suitable candidates for large scale electrical energy storage. In this study, the preliminary performance of a H2-Br2 fuel cell using both conventional as well as novel materials (Nafion and electrospun composite membranes along with Pt and RhxSy electrocatalysts) is discussed. The performance of the H2-Br2 fuel cell obtained with a conventional Nafion membrane and Pt electrocatalyst was enhanced upon employing a double-layer Br2 electrode while raising the cell temperature to 45°C. The active area and wetting characteristics of Br2 electrodes were improved upon by either pre-treating with HBr or boiling them in de-ionized water. On the other hand, similar or better performances were obtained using dual fiber electrospun composite membranes (PFSA/PPSU) versus using Nafion membranes. The RhxSy electrocatalyst proved to be more stable in the presence of HBr/Br2 than pure Pt. However, the H2 oxidation activity on RhxSy is quite low compared to that of Pt. In conclusion, a stable H2 electrocatalyst that can match the hydrogen oxidation activity obtained with Pt and a membrane with low Br2/Br− permeability are essential to prolong the lifetime of a H2-Br2 fuel cell

Selective Hydrogenation of Furfural in a Proton Exchange Membrane Reactor Using Hybrid Pd/Pd Black on Alumina

Conventional thermocatalytic hydrogenation employs high temperatures and pressures and often exhibits low selectivity toward desired products. Electrochemical hydrogenation can reduce energy input by operating at ambient conditions and improving process control and selectivity; however, electrocatalysts face stability and conductivity limitations. To overcome these obstacles, we physically mixed a traditional electrocatalyst (Pd black) with a hydrogenation‐active metal (Pd) supported on a conventional metal oxide support (alumina, Al2O3) and investigated electrochemical hydrogenation of furfural, a model biomass compound. Experiments were conducted in a proton exchange membrane (PEM) reactor, in which synthesized electrocatalysts were used as cathodes. Catalysts with Pd black and varying loadings of Pd on Al2O3 were used to determine the impact of hydrogen spillover on electrocatalytic hydrogenation mechanisms, selectivity, and rates. Observed hydrogenation rates and selectivities were linked to structural and compositional properties of the catalyst mixtures. Of the Pd black cathodes tested, 5 wt % Pd/Al2O3 exhibited production rates as high as pure Pd black and higher selectivity towards completely hydrogenated products. Improved selectivity and rates were attributed to a synergistic interaction between Pd black and 5 wt % Pd/Al2O3 in which Pd/Al2O3 increased the number of active sites, while Pd black provided stable conductivity.Breaking away from convention: The performance of hybrid cathodes, consisting of a traditional electrocatalyst (Pd black) with a hydrogenation‐active metal (Pd) supported on a conventional metal oxide support (Al2O3), is investigated using electrochemical hydrogenation of furfural in a proton exchange membrane reactor. Varying loadings of Pd on Al2O3 within the hybrid cathode elucidates the impact of structural and compositional properties of the catalyst mixtures on hydrogenation rates and selectivities.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152702/1/celc201901314-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152702/2/celc201901314.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152702/3/celc201901314_am.pd