Electrochemical sensors can be utilised for liquid or gas analyte detection. We are currently investigating the use of nanoporous gold (NPG) in a variety of sensing applications where the combination of microfabricated electrode arrays and nanoporous catalyst processing enables highly functional sensing materials for liquid and gas analysis. The highly active NPG has been shown to possess a number of advantages for catalytic reactions in solution.
We have demonstrated the advantages of NPG for fuel cell catalyst applications, volatile organic compound analysis in water, large molecule pharmaceutical sensing in solution and oxygen gas detection in water. We are extending the work on NPG to gas detection and have employed microelectrode arrays, post-processed with NPG, to monitor environmental CO2 and O2.
We have also developed a process for a low cost nanoporous material, manganese dioxide (MnO2) deposition on microelectrode arrays or templated deposition on copper nanotube arrays for oxygen gas reduction in fuel cell applications or gas evolution in a water splitting reaction. This material has potential as a gas sensor with desirable catalytic properties in a format which is nanoporous over a high conductivity support material to assist with signal detection for a material which is typically a poor electronic conductor.
We are also investigating a range of Ni-Fe based mixed oxide catalysts for oxygen gas reduction. The catalyst layers are prepared electrochemically using a simple and scalable potential cycling methodology on macro-scale substrates and chip-scale microelectrode arrays. The effect of substrate and oxide composition on the stability and electrocatalytic performance of the mixed oxides has been investigated and the mixed oxides have been shown to exhibit high stability and reusability under catalytic conditions.