Design, fabrication, and characterization of Hg²⁺ sensor based on graphite oxide and metallic nanoclusters

In this paper, sensors with field-effect transistor structure have been developed to detect low concentration of mercury ions (Hg²⁺) in water. These sensors are based on graphite oxide decorated with silver nanoclusters, where the change in the electrical current signal is the sensing parameter. By utilizing thermal evaporation process, interdigitated electrodes of gold were deposited on the surface of the sensor substrates. Graphite oxide (GO) was assembled between the interdigitated electrodes. Silver nanoclusters were generated inside an ultra-high vacuum (UHV) compatible system by sputtering and inert-gas condensation technique; then they were self-assembled on top of the graphite oxide. Each sensor was subjected to different concentrations of Hg²⁺ to test its sensitivity. The sensors showed better performance when incorporating silver nanoclusters with graphite oxide. The selectivity of the fabricated sensors was further investigated by testing different metal ions, and it revealed optimum response to Hg²⁺ among other metal ions, which makes them preferable for practical applications.