Modified Graphite Paper Based Miniaturized Electrochemically Optimized Hydrazine Sensing Platform

Abstract

In this work, a miniaturized platform for electrochemical detection of hydrazine, has been developed using droplet paper based three electrode system. Copper oxide cluster (CuO) immobilized on the surface of graphite sheet (Grp@CuO) is used as a working electrode. The developed Grp@CuO showed a surface-confined delayed redox response at an electrode potential (E1/2) −0.24 V vs Ag/AgCl in pH 7 phosphate buffer solution (PBS). The physicochemical characterization of the Grp@CuO revealed the electro deposition of CuO cluster on the surface of graphite sheet. Grp@CuO displayed selective electro-catalytic activity towards the detection of hydrazine in pH 7.0 PBS. A systematic linear increase in the oxidation current is observed in the range of 1 μM to 7 μM at an applied potential of −0.6 to 0.2 V vs Ag/AgCl with an excellent current sensitivity, lower detection limit (0.3482 μM). The fabricated miniaturized droplet-based sensor showed zero interference from other chemicals. Therefore, it is a viable option to be used in detection of hydrazine in real samples. Finally, the prepared platform was harnessed to real water samples for hydrazine detection.

Hydrazine Oxidation Electrocatalysis

“…Even undoped carbon can electro-oxidize hydrazine, albeit with high overpotentials. ,− It was first shown in 1965 on active carbon . Combining experiments and DFT calculations, the edge defects on undoped carbon were found to be more active than basal plane sites, in analogy to the ORR (Figure j) .…”

Understanding hydrazine oxidation electrocatalysis on undoped carbon

“…3a). 57,58 Ball-milled graphite is twice as active as graphite powder towards the HzOR, when comparing mass-normalized current densities (3.9 vs. 2.2 A g À1 at 1 V vs. RHE). The rise in massnormalized current is even more pronounced on rGO, with a 6-fold increase compared to graphite powder (18.4 A g À1 at 1 V vs. RHE).…”

“…To date, only two undoped carbons have been reported as HzOR electrocatalysts, and their active sites were not identified. 57,58 We now report a combined experimental and theoretical study into the role of undoped carbon towards HzOR electrocatalysis. Using crystallographically oriented graphites, as well as exfoliated and purposely defected carbons, we demonstrate the role of defect sites in HzOR electrocatalysis.…”

“…To date, only two undoped carbons have been reported as HzOR electrocatalysts, and their active sites were not identified. 57,58…”

Miniaturized Disposable Buckypaper-Polymer Substrate Based Electrochemical Purine Sensing Platform

“…[3][4][5][6][7][8] Plastic and paper stands out to be most potential substrate for fabricating point-of-care devices that require being in contact with bodily fluid such as blood, serum and urine depending upon their biocompatibility, flexibility and ease of use. [9][10][11] The integration of μFDs with electrochemical analysis gives new capabilities and functionalities that enables detection of several compounds with high accuracy.…”