Navegando por Autor "Diniz, Mariana Oliveira"

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Electrical characterization of V2O5/POMA deposited by the casting technique.
(2020) Diniz, Mariana Oliveira; Cestarolli, Dane Tadeu; Bianchi, Rodrigo Fernando; Guerra, Elídia Maria
Conductive polymer derivatives, such as poly-o-methoxyaniline (POMA), have been broadly used in different applications because they present characteristics similar to those of polyaniline. POMA can intercalate into a V2O5 matrix to improve its structural and electrical properties, and thin films of V2O5/POMA can be deposited by different techniques to extend their technological applications after intercalation reactions. Then, V2O5/POMA hybrid material was deposited by casting technique and characterizated for, further, to be ued as component in amperometric ammonia gas sensor. Our results show the influence of the deposition technique on electrical properties. Indeed, the values of parameters such as resistance, interface effects and conductivity slightly change according to the deposition technique being used.
Electrical impedance of V2O5/POMA hybrid film deposited by casting for application in ammonia gas sensor.
(2021) Diniz, Mariana Oliveira; Coelho, R. S.; Bianchi, Rodrigo Fernando; Guerra, Elidia Maria
The sensitivity evaluation of a vanadium pentoxide/poly-o-methoxyaniline hybrid material (V2O5/POMA) using casting deposition for the preparation of an ammonia gas sensor was investigated herein. V2O5/POMA was produced by the intercalation of V2O5 via sol–gel and o-methoxyaniline monomers. V2O5/ POMA thin film deposition onto electrodes was performed by casting. The electrical studies confirmed that V2O5/POMA exhibited increased complex impedance as a function of increasing ammonia concentration. The conductivity of the film decreased with increasing ammonia concentration due to the de-doping process. According to theoretical adjustment, a significant increase in the bulk and interfacial electrical resistance in the presence of ammonia was observed. The combination of these effects contributed to the high sensitivity of the prepared film in both the real and imaginary components of the complex impedance for ammonia gas in a range of 0 to 100 ppm, which indicated that the film is a good candidate for use as an ammonia sensing material.
Improving performance of polymer-based ammonia gas sensor using POMA/ V2O5 hybrid films.
(2019) Diniz, Mariana Oliveira; Golin, Alana Fernandes; Santos, Mirela de Castro; Bianchi, Rodrigo Fernando; Guerra, Elídia Maria
Conducting polymers such as polyaniline (PANi) have been widely investigated as ammonia gas sensors due to their intrinsic redox states, good environmental stability, and suitability for low-cost and variable changing in electrical conductivity when exposed to acid and basic gases. In this paper we used both a hybrid PANi derivative, poly(o-methoxyaniline) (POMA)-vanadium pentoxide (V2O5) film, and new ac electrical measurement strategies to increase the ammonia gas sensor performance. Complex impedance measurements of POMA/V2O5 hybrid film showed linearity in response and a high sensitivity to ammonia in the 0–20 ppm range in both real (around 800%) and imaginary (around 3000%) components, which indicated that the film is a good candidate to use as an ammonia sensing material. FTIR spectra presented typical V2O5 and POMA bands and also presented a shifting to higher wave numbers in bands referring to the vanadyl group and primary amines, which indicated the presence of hydrogen bonds between oxide and polymer. Finally, the Cole–Cole theoretical model with an interface effect provided a good fit for the experimental results from electrical ac measurements.