Tungsten carbide-based electrochemical sensors for hydrogen determination in gas mixtures

An amperometric study of gas-diffusion electrodes (GDE) catalysed by two ty pes of tungsten carbide, WC(1) and WC(2), which differ considerably in thei r specific surface area (0.5 and 6 m(2) g(-1)), was carried out. The H-2-ai r gas mixture (H-2 1-4%) measurements show that for this range of hydrogen concentration the hydrogen limiting diffusion current (i(d(H2))) may be att ained so that a curve of limiting current density against hydrogen concentr ation can be obtained. The response and stability of the electrode performa nce were compared to those of platinum catalysed GDEs. The most promising f or use in amperometric hydrogen sensing is the WC(1) catalyst of small spec ific surface area. Electrodes catalysed with this catalyst show inferior re sponse time in comparison to electrodes catalysed with the other two cataly sts (WC(2) and Pt) but their overall stability is much better.