the hydrophilic carbonaceous component may comprise a minor portion of carbon graphite to enhance electrical conductivity the hydrophobic component 26 may comprise a fluorinated polymer e g polytetrafluoroethylene ptfe polyvinylidene fluoride pvdf polyvinyl fluoride pvf a combination of fluorinated polymers or any other suitable hydrophobic material or combination of materials regarding the respective weight percentages of the respective hydrophilic and hydrophobic components the mesoporous layer may comprise between about 80 wt and about 95 wt of the carbonaceous component or more specifically about 80 wt of the carbonaceous component in high operational humidity applications and between about 90 wt and about 95 wt of the carbonaceous component in low operational humidity applications in many embodiments of the present invention the mesoporous layer 24 is more effective in addressing water management issues if it is positioned against the membrane electrode assembly 30 of the fuel cell 10 as opposed to being positioned to face the flow field of the cell nevertheless it is contemplated that the diffusion media substrate 22 may carry the mesoporous layer 24 along either major face 21 23 of the substrate 22 regardless of which face is positioned against the membrane electrode assembly 30 further the mesoporous layer 24 may cover all or a portion of the face along which it is carried as is illustrated in fig2 the mesoporous layer 24 at least partially infiltrates the diffusion media substrate 22 the extent of infiltration illustrated schematically by showing the first surface.