Effect of ordered mesoporous carbon contact layer on the sensing performance of sputtered RuO₂ thin film pH sensor

The effect of contact layer on the pH sensing performance of a sputtered RuO₂ thin film pH sensor is investigated. The response of pH sensors employing RuO₂ thin film electrodes on screen-printed Pt, carbon and ordered mesoporous carbon (OMC) contact layers are measured over a pH range from 4 to 10. Working electrodes with OMC contact layer are found to have Nernstian pH sensitivity (-58.4mV/pH), low short-term drift rate (5.0mV/h), low hysteresis values (1.13mV) and fast reaction times (30s), after only 1h of conditioning. A pH sensor constructed with OMC carbon contact layer displays improved sensing performance compared to Pt and carbon-based counterparts, making this electrode more attractive for applications requiring highly-accurate pH sensing with reduced conditioning time.