Binary platinum–ruthenium/Nafion electrodes for the detection of hydrogen

In this paper, binary Pt–Ru/Nafion working electrodes for amperometric sensing of hydrogen were characterized and evaluated. Pt was alloyed with Ru on Nafion membranes by the Takenaka–Torikai method (T–T method). By controlling the amount of Ru in the alloys, the morphologies of the films varied from coarse particles to fine granules, some of which were fine enough to merge into the substrate. The response currents of all electrodes were proportional to hydrogen concentrations ranging from 100 to 1000 ppm. The sensitivity of the Pt–Ru/Nafion electrodes was inversely proportional to the amount of Ru in the electrodes. However, both response and recovery times as well as sensitivity of the Pt80Ru20/Nafion electrode were improved while increasing the operational temperature. Binary electrodes that possessed a bi-functional mechanism for hydrogen oxidation were found to mitigate the impact of CO poisoning effectively only at low applied potential of 0.2 V (vs. Ag/AgCl). Moreover, the Pt80Ru20/Nafion electrode entailed fast response and recovery times (90% response and recovery times) within 40 s.