IMPROVED ELECTROCATALYTIC ACTIVITY OF OXYGEN REDUCTION ON PLATINUM USING NANO-COBALT IN DIRECT METHANOL FUEL CELL CATHODE ELECTRODES

摘要

High surface area nanometal particles of nano-cobalt (n-Co) (approx 8 nm particles), produced at QuantumSphere Inc., were blended in various ratios with Pt and Nation~® ionomer, and investigated for their electrocatalytic activity in the oxygen reduction reaction (ORR). The ORR was evaluated by voltammetry using Pt/n-Co blended catalyst on glassy carbon to determine both kinetic activity and as an indicator of direct methanol fuel cell (DMFC) cathode performance. Kinetic enhancement was observed for Pt:n-Co where n-Co is 30-50 % (by weight) of the catalyst mixture, including a minimum of 10 mV improvement in the open circuit voltage (OCV). By Tafel slope measurements, it is clear that the mechanism for ORR does not change, however the reaction rate is enhanced by addition of n-Co to Pt in the catalytic ink. For ink compositions similar to those used for standard DMFC cathodes, eliminating 50% of the Pt black resulting in 50% higher energy density while reducing total catalyst cost by roughly 44%.