Editing Direct methanol fuel cell (section)

== The cell ==
In contrast to [[indirect methanol fuel cell]]s, where methanol is reacted to [[hydrogen]] by [[steam reforming]], DMFCs use a methanol solution (usually around 1[[molarity|M]], i.e. about 3% in mass) to carry the reactant into the cell; common operating temperatures are in the range {{cvt|50 to 120|°C}}, where high temperatures are usually pressurized.
DMFCs themselves are more efficient at high temperatures and pressures, but these conditions end up causing so many losses in the complete system that the advantage is lost;<ref>Dohle, H.; Mergel, J. & Stolten, D.: Heat and power management of a direct-methanol-fuel-cell (DMFC) system, Journal of Power Sources, 2002, 111, 268-282.</ref> therefore, atmospheric-pressure configurations are currently preferred.

Because of the methanol cross-over, a phenomenon by which methanol diffuses through the membrane without reacting, methanol is fed as a weak solution: this decreases efficiency significantly, since crossed-over methanol, after reaching the air side (the cathode), immediately reacts with air; though the exact kinetics are debated, the result is a reduction of the cell voltage. Cross-over remains a major factor in inefficiencies, and often half of the methanol is lost to cross-over. Methanol cross-over and/or its effects can be alleviated by (a) developing alternative membranes (e.g.<ref>{{cite journal|last=Wei|first=Yongsheng|title=A novel membrane for DMFC – Na2Ti3O7 Nanotubes/Nafion composite membrane: Performances studies|journal=International Journal of Hydrogen Energy|year=2012|volume=37|issue=2|pages=1857–1864|doi=10.1016/j.ijhydene.2011.08.107|display-authors=etal}}</ref><ref>{{cite web |title=Safe space: improving the "clean" methanol fuel cells using a protective carbon shell |url=https://bioengineer.org/safe-space-improving-the-clean-methanol-fuel-cells-using-a-protective-carbon-shell/ |website=Bioengineer.org |date=4 December 2020 |access-date=30 December 2020}}</ref>), (b) improving the electro-oxidation process in the catalyst layer and improving the structure of the catalyst and gas diffusion layers (e.g.<ref>{{cite journal|last=Matar|first=Saif|author2=Hongtan Liu|title=Effect of cathode catalyst layer thickness on methanol cross-over in a DMFC|journal=Electrochimica Acta|year=2010|volume=56|issue=1|pages=600–606|doi=10.1016/j.electacta.2010.09.001}}</ref> ), and (c) optimizing the design of the flow field and the membrane electrode assembly (MEA) which can be achieved by studying the current density distributions (e.g.<ref>{{cite journal|last=Almheiri|first=Saif|author2=Hongtan Liu|title=Separate measurement of current density under land and channel in Direct Methanol Fuel Cells|journal=Journal of Power Sources|year=2014|volume=246|pages=899–905|doi=10.1016/j.jpowsour.2013.08.029|bibcode=2014JPS...246..899A}}</ref> ).

Other issues include the management of [[carbon dioxide]] created at the [[anode]], the sluggish dynamic behavior, and the ability to maintain the solution water.

The only waste products with these types of fuel cells are [[carbon dioxide]] and water.