Investigation of Reduced Graphene Oxide and a Nb-Doped TiO₂ Nanotube Hybrid Structure To Improve the Gas-Sensing Response and Selectivity

Abstract

The precise detection of flammable and explosive gases and vapors remains an important issue because of the increasing demand for renewable energy sources and safety requirements in industrial processes. Metal oxides (TiO2, SnO2, ZnO, etc.) are very attractive materials for the manufacturing of chemical gas sensors. However, their gas selectivity issues and further improvement in the sensing response remain a significant challenge. The incorporation of metal oxides with two-dimensional (2D) graphene oxide (GO) is considered to be a promising approach to obtaining hybrid structures with improved gas-sensing performance. Herein, we report the development of GO and niobium-doped titanium dioxide nanotube (NT) hybrid structures with a tunable selectivity and sensing response against hydrogen gas, achieved by properly controlling the degree of reduction and concentration of GO. The effects of these parameters are systematically studied in terms of the response amplitude and selectivity. It was found that, compared to undoped titanium dioxide nanotubes, the hybrid material with an optimal concentration of reduced-GO and the introduction of niobium shows an increase in hydrogen response of about an order of magnitude and a simultaneous reduction of the response to possible interfering compounds such as carbon monoxide and acetone, thus providing enhanced selectivity. This research may provide an efficient way to enhance the chemical sensing performance of metal oxide nanomaterials.

Dopant-mediated surface charge imbalance for enhancing the performance of metal oxide chemiresistive gas sensors

“…6–10 Frequently, metal oxides in pristine forms have suffered from issues of sensitivity toward a particular gas and also selectivity amidst an array of gases. 11–15 Besides morphology tuning, surface functionalization, and changing the material dimension, doping is a strategy that has been successfully used in overcoming the above shortcomings of pure metal oxides. 16–19 What really matters in choosing a dopant is to define the parameters that constitute the concept of suitability.…”

Chemical Gas Sensors Studied at SENSOR Lab, Brescia (Italy): From Conventional to Energy-Efficient and Biocompatible Composite Structures

“…It is also compelling to notice that, by the addition of only a WO x surface layer, the electrical signal of the structure underwent a dramatic change upon the introduction of VOCs, differently from pure TiO 2 that displayed weak variations (Figure 8). Similarly, the coupling of V 2 O 5 with the anatase TiO 2 enhanced the response of material towards ethanol at 200 • C [82].…”

Effective and Robust Parameter Identification Procedure of a Two-Site Langmuir Kinetics Model for a Gas Sensor Process

“…This interface has multiple sections: (1) data import (upper left corner), (2) data display including time, resistance, and experimental and theoretical conductance (left), (3) results including parameter values, coefficients of determination, and GA fitness (lower left corner), (4) command buttons including "Initialize" to set the gas concentration, "Estimate" to estimate the parameters, "Optimize" to utilize models to fit curves, and "Save" to save the image and results (top right), (5) concentration edit (right), and ( 6) plots for the model plot with the given parameters (bottom right). We must highlight that the latest tLKGA GUI will be released via an open-source GitHub repository.…”