pH Sensitivity of Screen-Printed Sensors based Onamorphous and Crystalline RuO2 and the Impact of Conducting and Inert Binders

Whereas crystalline RuO2 is well-known in thermally prepared layers, the superior sensitivity dE/dpH of the amorphous oxide prepared by a sol-gel process has not been considered in detail so far. RuO2 pastes, bound with ethyl cellulose, nafion, acrylic resin, and carbon black show Nernstian behavior both in standard pH buffer solutions and in corrosive media. Sintered layers appear to be less sensitive and tend to age. A residual content of chloride influences the properties of the electrode. The impact of the solution resistance on the pH response is obvious during acid-base titrations, which differ considerably from measurements in standard buffer solutions.