Hybrid Nanomaterials for Low-cost Detection of Chemicals in Water

1. Hybrid Nanomaterials for Low-cost Detection of Chemicals in Water Guihua (Rose) Zhou Graduate Student PI: Junhong Chen University of Wisconsin-Milwaukee 04-07-2014

2. Objective &Approach • Selective detection of heavy metal ions (Hg2+) in drinking water. • *MCL: maximum contaminant level specified by EPA • To fabricate a field-effect transistor (FET)-based water sensing platform. • To integrate proposed sensor into existing water equipment for pilot test Schematic of the Hybrid TRGO-Au NP Sensing Platform Thioglycolic Acid (TGA) as Probe Fig. 1. Electrical detection of analytes through the introduction of functionalized Au NPs in a TRGO FET platform

3. Methodology Fig. 3. scanning electron microscope (SEM) image of a TRGO across the electrodes. Fig. 2. Fabrication process of TRGO/Au NP/TGA hybrid. • Fabrication Process: • rGO ( thermally reduced grapheme oxide in 400 ̊C, Ar for 1 hr) • Au NPs( sputter for 2 nm) • TGA( 1 hr reaction, wash with DI) Fig. 4. SEM image of the Au NPs uniformly decorated on the GO sheets.

4. Result • The drain current versus time was monitored and then the sensitivity was obtained for different target Hg2+ concentrations (Fig. 5). • There was no noticeable change observed upon the addition of DI water, implying the specificity and stability of the device. • The sensor responded within a few seconds for the Hg2+ to diffuse through the liquid drop on the top of the device. • The rGO/TGA-Au NP hybrid sensor indeed gave no obvious response upon the addition of Na+ and Ca2+, demonstrating the specificity of the rGO/TGA-Au NP hybrid sensor.