Proton Exchange Membrane Fuel Cell with a Pt‐free Cathode and a Freely Diffusing Electron Acceptor

In a fuel cell, almost 80% efficiency loss arises due to the cathode; consequently, the cathode requires the largest amount of precious metal catalyst. Here, we show a precious‐metal‐free cathode for a proton exchange membrane fuel cell (PEMFC) containing only carbon nanoparticles as the catalyst and a freely diffusing molecule as the electron acceptor. Factors controlling the true rate of electrochemical reactions are amplified just by using carbon nanoparticles, leading to a carbon corrosion‐free PEMFC delivering 154 mW/cm2 at 358 mA/cm2 without any precious metals.