UC Riverside

The increasing environmental contamination, especially from heavy metals, toxic gases,radioactive materials, pesticides, and pathogens, is a global concern. In this regard, electrical and electrochemical sensors attracted a huge attention. The efficiency and sensitivity of any sensor system is highly dependent on its sensing material interface. This work is focused on synthesis, characterization, and optimization of different nanomaterials (0D, 1D, and 2D) for the sensitive detection of three environmental contaminants, i.e. bacteria, heavy metals (Arsenic), and toxic gases (NO2). Tuning the material properties to harvest the highest efficiency, for bio/chemical sensors, is a main challenge in every project. A linker-free gold magnetite nanoparticles (Fe3O4-Au NPs) was synthesized using a novel approach that provided very tiny magnetite (~ 10nm) NPs with a high surface area, and synergistic electrocatalytic effects of the two nanomaterials due to the zero spacing between them. Fe3O4-Au NPs-ionic liquid was modified on glassy carbon electrode (GCE) and achieved a trace level detection of As(III) in water using anodic stripping voltammetry. Non-lytic M13 phage was chemically loaded to AuNPs-GCE and used for highly sensitive, selective, and stable (thermally and chemically) impedimetric detection of E. coli in water. A detailed experimental study of what really matters for getting pristine graphene-like rGO thin film, supported by DFT calculations, was conducted. The rGO thin film was then integrated into microfabricated interdigitated and single gap devices with back gating for field-effect transistor (FET) measurements and applications. The material electronic properties of bandgap and charge carrier mobility were monitored and linked to the material quality. The resulting high quality rGO thin film served as a semiconductor channel in FET-based electrical sensor for detection of bacteria and heavy metals. Lastly, MoSe2, and ternary MoSe(2-X)TeX alloys were synthesized using chemical vapor deposition (CVD), with a gradient variation in (x) to tune the band gap and carrier mobility of the corresponding alloys for near-infrared (NIR) optoelectronic applications. Orders of magnitude enhancement in the device output was observed by Te doping. By a precise control of the epitaxial growth factors, Janus MoSe(2-X)TeX/MoSe(2-y)Tey heterostructure with defect-free interface was synthesized, and an antiambipolar transistor was recorded for the first time.