It is important to develop a reliable gas sensor for the detection of H2 that is expected for clean energy. Expanded polytetrafluoroethylene (ePTFE) membrane is a chemically stable substance and has high gas permeability without permeation of aqueous electrolytes.

A study has been made of ion implantation of various kinds of ions into ePTFE membranes with fluenses of 1 × 1013, 1 × 1014, 1 × 1015, and 5 × 1015 ions/cm2. After Au ion plating to ion-implanted ePTFE, we produced the electrochemical H2 gas sensor using the gas permeable electrode.

The electrochemical gas sensor using a gas permeable electrode modified by ion implantation showed a good sensitivity and selectivity for H2 detection. Especially the sensor used N+-, N2+-, O+-, and O2+- implanted ePTFE membrane with fluences of above 1 × 1015 ions/cm2 showed significant effect, which was more than 20 times higher than that of control.

Morphology change of ePTFE by ion implantation was examined by SEM and chemical bonding structure of the irradiated ePTFE surface was analyzed by FT-IR–ATR spectroscopy. With ion-implanted ePTFE, internodal distance, density between the nodes, and C C bonds induced by ion implantation were major factors influencing the H2 detection current.