The Design of Low Pt Loading Electrodes for Use in Fuel Cell-Based Breath Alcohol Sensors

Modern breath alcohol sensors (BrAS) employ an electrochemical sensor based upon fuel cell technology. These devices closely mimic power generating fuel cell technology from 30 years ago, with each electrode containing massive amounts of Pt black catalyst (∼10−20 mg cm −2 ). Here we report low-loading gas diffusion electrodes (GDE) fabricated using 40% Pt/C and studied the impact of Pt loading on sensor performance. The optimal loading was determined to be ca. 1 mg Pt cm −2 , which gives the optimal balance between Pt utilization and ethanol sensitivity. The ethanol sensitivity performance achieved with the GDE paired with a Nafion membrane was similar to that achieved with a commercial MEA that employs a Pt loading of 13.7 mg cm −2 and a PVC membrane. When paired with porous-PVC membranes our GDEs showed even greater sensitivity, readily exceed that of the commercial MEA despite the fact it employs 92% less Pt. The highest sensitivity was achieved when the GDE was paired to a gold-coated PVC membrane (Au-PVC), where the thin layer of gold is believed to enhance the membrane∣electrode interface. Thus, this sensor composition is proposed as a viable lower-cost alternative to the high-loading Pt black electrodes currently used in commercial BrAS technology.