Novel graphene electrochemical transistor with ZrO2/rGO nanocomposites functionalized gate electrode for ultrasensitive recognition of methyl parathion

A novel graphene electrochemical transistor (GECT) based on zirconia/reduced graphene oxide (ZrO 2 /rGO) nanocomposites functionalized gate electrode and graphene as channel was successfully designed and fabricated for highly sensitive detection of methyl parathion (MP). ZrO 2 /rGO nanocomposites were co-electrodeposited on a glassy carbon electrode considering the special affinity of ZrO 2 toward phosphate groups and high specific surface area of rGO. The sensing mechanism is attributed to the change of effective gate voltage applied to GECT induced by the electrochemical reactions of MP at the functionalized gate electrode, thus tuning the channel carrier concentration and the channel current. Due to the excellent electrocatalytic activity of ZrO 2 /rGO on the gate and the high carrier mobility of graphene in the channel, the developed sensor exhibited excellent sensing performances with ultra-low detection limit (10 pg/mL) and ultra-wide linear range from 10 pg/mL to 10 μg/mL, which especially stand out of the reported devices. The GECT sensor also showed good selectivity toward usual interferents and strong practicality through testing MP in Chinese cabbage samples. The developed GECT devices provided not only the novel platform for pesticide detection with high sensitivity but the new method of enhancing the sensing performance through specifically functionalized gate electrode.