Fuel Cell Polarization Curve.

<p>The performance of the fuel cell is characterized through its output voltage (blue, left axis) and power density (red, right axis) as functions of output current density. A 2 mm² device exhibits an open-cell voltage of 192 mV and achieves maximum power output of more than 180 µW cm⁻² when sourcing 1.5–1.85 mA cm⁻².