Patent ID: 7332240

Claim:
A device configured to convert a hydrogenous fuel source to electrical energy, said device comprising: an electrochemical conversion assembly configured to partition said device into first and second flow field regions; a first reactant input and a first product output in communication with said first flow field region; a first diffusion media comprising a porous diffusion media substrate configured to pass multiphase reactants between said first flow field region and said electrochemical conversion assembly; a second reactant input and a second product output in communication with said second flow field region; and a second diffusion media comprising a porous diffusion media substrate configured to pass multiphase reactants between said second flow field region and said electrochemical conversion assembly, wherein said device is configured such that at least one of said first and second diffusion media comprise a region subject to relatively high H 2 O concentrations and a region subject to relatively low H 2 O concentrations, a mesoporous layer is carried along at least a portion of a major face of one of said first and second diffusion media substrates and comprises a hydrophilic carbonaceous component and a hydrophobic component, and said mesoporous layer occupies a substantially greater portion of one of said high H 2 O region and said low H 2 O region relative to the other of said high H 2 O region and said low H 2 O region, wherein (1) at least one of said first and second diffusion media substrate comprises an increased thickness portion and a reduced thickness portion and said mesoporous layer is carried along only said reduced thickness portion of at least one of said first and second diffusion media substrates and/or (2) said mesoporous layer at least partially infiltrates at least one of said first and second diffusion media substrates to a depth of greater than zero μm to about 10 μm in said high H 2 O regions and a depth of greater than 0 μm to about 25 μm in said low H 2 O regions; and said hydrophilic carbonaceous component comprises a moderate surface area carbon characterized by mean particle size of between about 15 nm and about 70 nm in said high H 2 O regions.