Graphene oxide based free-standing films for humidity and hydrogen peroxide sensing (original) (raw)
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Journal of Colloid and Interface Science, 2011
An aqueous dispersion of reduced graphene oxide (rGO) has been successfully prepared via chemical reduction of graphene oxide (GO) by hydrazine hydrate in the presence of aniline for the first time. The noncovalent functionalization of rGO by aniline leads to a rGO dispersion that can be very stable for several months without the observation of any floating or precipitated particles. Several analytical techniques including Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) have been used to characterize the resulting rGO. Taking advantages of the fact reducing ability of aniline toward AgNO 3 , we further demonstrated the subsequent decoration of rGO with Ag nanoparticles (AgNPs) by in situ chemical reduction of silver salts. It was found that such AgNP/rGO nanocomposites exhibit good catalytic activity toward the reduction of hydrogen peroxide (H 2 O 2 ), leading to an enzymeless sensor with a fast amperometric response time of less than 2 s. The linear detection range is estimated to be from 100 lM to 80 mM (r = 0.9991), and the detection limit is estimated to be 7.1 lM at a signal-to-noise ratio of 3.
A route to detect H2 in ambient conditions using a sensor based on reduced graphene oxide
Sensors and Actuators A-physical, 2020
Change in resistance of rGO/AZO and AZO sensor under an accumulated exposition at 40 sccm of H2 (g) over time. Highlights Positioning of GO flakes across electrodes using a positive dielectrophoretic force. A rGO work function in the range of 4.7-4.9 eV At 40 sccm, the sensitivity of the rGO sensor is of ~100 % at 1 V Relative humidity is a critical factor for the performance of rGO Abstract Graphene Oxide (GO) is considered an ideal candidate for the fabrication of hydrogen gas (H2 (g)) sensors due to its excellent capabilities for direct wiring, thanks to the presence of functional groups, which provide an opportunity to modify its chemical functionalities. In this study, we have fabricated a H2 (g) sensor based J o u r n a l P r e-p r o o f on the precise positioning of GO flakes across sputtered aluminium-doped ZnO (AZO) electrodes on a glass substrate using a positive dielectrophoretic force (DEP). GO flakes assembly was performed between AZO electrodes gap of 4 m and optimized by controlling the DEP parameters. A chemical reduction using a solution of 10 mM sodium borohydride was used to enhance the conductivity of the GO flakes up to two orders of magnitude. The arrangement of the GO flakes, the efficiency of the reduction process, the morphology and the surface potential of these was analyzed by Atomic Force and Kelvin Probe Microscopies. A reduced Graphene Oxide (rGO) work function in the range of 4.7-4.9 eV was obtained. Moreover, the H2 (g) response of rGO/AZO sensor was studied by two types of tests. First test consists of a single 10 min exposure of pure H2 (g), collecting the IV directly data in order to obtain the sensitivity of the rGO to be of ~100 % at 1 V. Second test consists of a batch of different time exposures to analyze the stress performance and the saturation level of the sensor. Finally, the impact of the ambient conditions on our sensor sensitivity was studied.
Sensors and Actuators B: Chemical, 2014
We report the synthesis and application of MnO 2 nanotubes/reduced graphene oxide nanocomposite (MnO 2 NTs/RGO NCs) for the detection of hydrogen peroxide. The MnO 2 NTs/RGO NCs were synthesized via a simple single-step hydrothermal process in acidic KMnO 4 solution without the use of surfactants or templates. The nanocomposites were synthesized with different percentages of RGO (1, 3 and 5%). Field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction results confirmed the growth of MnO 2 NTs on the RGO surface. Electrochemical properties of the MnO 2 NTs/RGO NCs electrode were investigated by amperometry, cyclic voltammetry and electrochemical impedance spectroscopy. The observations confirmed that the charge transfer resistance of the glassy carbon electrode (GCE) coated with MnO 2 NTs/RGO NCs was significantly decreased. The limit of detection and limit of quantification S/N = 3) of two linear segments (0.1-30 mM and 40-80 mM of H 2 O 2 ) are estimated as 1.29 M, 4.29 M and 0.82 M, 2.75 M, respectively. The reproducibility experiment results prove that the use of MnO 2 NTs/RGO NCs is feasible for the quantitative detection of H 2 O 2 in the range of 0.1-80 mmol L −1 .
Resistive chemical sensors were developed having as sensitive film graphene oxide (GO) spin-coated on glass. Sensor electrical behaviour to room temperature relative humidity was evaluated. High sensitivity characterizes GO sensor. However, it lacks repeatability and long term stability. To this end, we developed spin-coated GO sensors with different active layer thickness, which were subjected to subsequent thermal annealing steps. It was found that the resulting reduced GO (rGO) sensors demonstrate excellent stability compromising, though, the sensitivity which mainly depends on the number of annealing steps and film thickness. Finally, we propose a rapid, transparent, low-power consumption rGO sensor, enabling its use in relevant applications.
Sensors and Actuators B: Chemical, 2015
Novel impedance-type humidity sensors were made by coating diamine-functionalized graphene oxide (GO) films on alumina or plastic substrates. Ethylenediamine (EA) and 1,6-hexanediamine (HA) were used to functionalize GO using N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) (EDC/NHS) as the coupling reagent. The effects of the chain length of diamine on the electrical and humidity-sensing properties of the diamine-functionalized GO film were investigated. The diamine-functionalized GO film was characterized by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). The impedance-type humidity sensor that was made of the EA-GO film exhibited a wide range of working humidities, a high sensitivity, satisfactory linearity, a small hysteresis, high flexibility, a short response/recovery time, a weak dependence on temperature and high long-term stability. The linearity of the humidity sensor depended on the applied frequency. The ions (H 3 O +) dominate the conductance of the diamine-functionalized GO film.
Talanta, 2013
Electrochemical detection of H 2 O 2 was investigated on a Nafion/exfoliated graphene oxide/Co 3 O 4 nanocomposite (Nafion/EGO/Co 3 O 4) coated glassy carbon electrode. The morphological characterization was examined by scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy. The modified electrode showed well defined and stable redox couples signal in both alkaline and natural aqueous solutions with excellent electrocatalytic activity for oxidation of hydrogen peroxide. The response of the modified electrode to H 2 O 2 was examined using amperometry (at 0.76 V vs. Ag/AgCl reference electrode) in a phosphate buffer solution (pH 7.4). The detection limit was 0.3 mmol L À 1 with a linearity of up to four orders of magnitude and a sensitivity of 560 mA mmol À 1 L cm À 2. The response time of the electrode to achieve 95% of the steady-state current was recorded at 4 s. The ability of the sensor for routine analyses was demonstrated by the detection of H 2 O 2 presents in milk samples with appreciable recovery values. In addition, the Nafion/EGO/Co 3 O 4-GCE showed good selectivity for H 2 O 2 detection in the presence of ascorbic acid, uric acid, and glucose. The attractive analytical performances such as remarkable catalytic activity, good reproducibility, long term stability, and facile preparation method made this novel nanocomposite electrode promising for the development of effective H 2 O 2 sensor.
Application of Graphene/Nickel Oxide Composite as a Humidity Sensor
Egyptian Journal of Chemistry, 2020
Molecular modeling analyses at Density functional theory DFT level was used to study the possible application of modified graphene (G) as gas sensor. A model molecules of graphene sheet was constructed then modified with nickel oxide NiO attached to graphene through covalent bonds forming G/NiO composite. DFT at B3LYP/6-31G(d,p) was utilized to investigate the physical properties of G; G/NiO; G/NiO/2H2O. Results show that interacting G/NiO composite with water molecules lowers the calculated energy of the formed structure reflecting the possibility of exposing G/NiO structure to humidity, since it forms more energetically stable composition that can be detected by a proper circuit. However, water addition results in significant reduction in the TDM which would enhance its stability. This would increase the efficiency of G/NiO material as a humidity sensor. Mapping molecular electrostatic potential indicated that, the impact of interacting with G/NiO composite through Ni end increases electron cloud on the terminals ensuring the great ability of this region to sense different water molecules. It is concluded that, the change in the physical properties of G/NiO under the influence of water molecules took place. Collecting these data together, it is clear that the studied G/NiO composite could act as humidity sensor.
AIP Advances, 2016
The oxidation properties of graphene oxide (GO) are systematically correlated with their chemical sensing properties. Based on an impedance analysis, the equivalent circuit models of the capacitive sensors are established, and it is demonstrated that capacitive operations are related to the degree of oxidation. This is also confirmed by X-ray diffraction and Raman analysis. Finally, highly sensitive stacked GO sensors are shown to detect humidity in capacitive mode, which can be useful in various applications requiring low power consumption.