A suspension containing MWCNT in ethanol (1.67 mL g -1 ) and 2 vol% of a 5 wt% Nafion solution was sonicated for 15 minutes. The suspension was then dropcasted on a defined area of carbon paper (0.1 mL cm -2 ) that was masked with Teflon tape followed by overnight drying at room temperature. The electrode was then taped to a metal rod using a copper tape and the metal rod and copper tape was wrapped with Parafilm.