Interfacial Capacitance of Graphene Oxide Films Electrodes: Fundamental Studies on Electrolytes Interface Aiming (Bio)Sensing Applications

Abstract

The understanding of bidimensional materials dynamics and its electrolyte interface equilibrium, such as graphene oxide (GO), is critical for the development of a capacitive biosensing platform. The interfacial capacitance (C i ) of graphene-based materials may be tuned by experimental conditions such as pH optimization and cation size playing key roles at the enhancement of their capacitive properties allowing their application as novel capacitive biosensors. Here we reported a systematic study of C i of multilayer GO films in different aqueous electrolytes employing electrochemical impedance spectroscopy for the application in a capacitive detection system. We demonstrated that the presence of ionizable oxygen-containing functional groups within multilayer GO film favors the interactions and the accumulation of cations in the structure of the electrodes enhancing the GO C i in aqueous solutions, where at pH 7.0 (the best condition) the C i was 340 μF mg À 1 at À 0.01 V vs Ag/AgCl. We also established that the hydrated cation radius affects the mobility and interaction with GO functional groups and it plays a critical role in the Ci, as demonstrated in the presence of different cations Na + = 640 μF mg À 1 , Li + = 575 μF mg À 1 and TMA + = 477 μF mg À 1 . As a proof-ofconcept, the capacitive behaviour of GO was explored as biosensing platform for standard streptavidin-biotin systems. For this system, the C i varied linearly with the log of the concentration of the targeting analyte in the range from 10 pg mL À 1 to 100 ng mL À 1 , showing the promising applicability of capacitive GO based sensors for label-free biosensing.

Ab-initio Molecular Dynamics Simulation of the Changes in the Optical Properties of 2D MoS₂ When Doped with Pt at 300 K

“…Bidimensional materials show different interesting physical properties, making them suitable for many potential applications, including energy storage [1][2][3], biomedical research [4][5][6], field-effect transistors (FETs) [7][8][9][10], as well as sensors and biosensing [11,12]. One of such materials is Molybdenum disulfide, MoS2, a layered dichalcogenide with a hexagonal structure similar to graphene.…”

Effect of Pt Decoration on the Optical Properties of Pristine and Defective MoS2: An Ab-Initio Study

“…Bidimensional materials show different interesting physical properties, making them suitable for many potential applications, including energy storage [ 1 , 2 , 3 ], biomedical research [ 4 , 5 , 6 ], field-effect transistors (FETs) [ 7 , 8 , 9 , 10 ], as well as sensors and biosensing [ 11 , 12 ]. One of these materials is Molybdenum disulfide, MoS 2 , a layered dichalcogenide with a hexagonal structure reminiscent of graphene.…”