Chemically engineered plasmonic Au-gallium oxide nanocomposites for harsh environment applications: an investigation into thermal and chemical robustness

Enhanced thermal, chemical, and mechanical properties of different metal nanoparticle morphologies integrated with metal oxides have been reported in multiple instances. The chemical and material robustness of metal nanoparticles incorporated surficially and into the bulk of distinct as well as spontaneously formed morphologies of metal oxides through solution-based and microwave-based approaches are investigated in this study. These composites were tested for their chemical and material robustness by exposing films formed on quartz substrates to high temperatures (800 °C) in an air ambient as well as to extreme conditions of pH, often encountered in harsh environment applications such as sensing and catalysis. The changes in the optical properties and crystallinity have been studied using in situ absorption and ex situ X-ray diffraction analyses and electron microscopy. The trends observed with respect to the changes in the plasmonic absorbance were validated theoretically and found to be in reasonable agreement with the experimental data. Confirmations of the phenomena occurring in different morphologies and architectures were thereby corroborated through careful interpretations from experiments and predictions from theoretical models. We, therefore, report a simple solution-based process for achieving engineered harsh environment-compatible nanocomposites through studies specifically tailored for such applications such as catalysis, sensing, energy storage, and enhanced luminescence. The significance of the work is the ability to fabricate solution-based AGO composites with high thermal and chemical stabilities, enabling sensing at elevated temperatures of up to 800 °C.