Role of Defect Engineering and Surface Functionalization in the Design of Carbon Nanotube-Based Nitrogen Oxide Sensors

Abstract

Nitrogen oxides (NOx) are among the main atmospheric pollutants; therefore, it is important to monitor and detect their presence in the atmosphere. To this end, low-dimensional carbon structures have been widely used as NOx sensors for their outstanding properties. In particular, carbon nanotubes (CNTs) have been widely used as toxic-gas sensors owing to their high specific surface area and excellent mechanical properties. Although pristine CNTs have shown promising performance for NOx detection, several strategies have been developed such as surface functionalization and defect engineering to improve the NOx sensing of pristine CNT-based sensors. Through these strategies, the sensing properties of modified CNTs toward NOx gases have been substantially improved. Therefore, in this review, we have analyzed the defect engineering and surface functionalization strategies used in the last decade to modify the sensitivity and the selectivity of CNTs to NOx. First, the different types of surface functionalization and defect engineering were reviewed. Thereafter, we analyzed experimental, theoretical, and coupled experimental–theoretical studies on CNTs modified through surface functionalization and defect engineering to improve the sensitivity and selectivity to NOx. Finally, we presented the conclusions and the future directions of modified CNTs as NOx sensors.

Recent Advances in the Development of Nanocarbon-Based Electrocatalytic/Electrode Materials for Proton Exchange Membrane Fuel Cells: A Review

“…To enhance the adhesion between catalytic nanoparticles and the surface of the structured support and to increase the reactivity of CNTs by creating active sites that facilitate the distribution of catalyst nanoparticles, the support undergoes chemical or physical pre-modification [102][103][104][105][106]. In the case of chemical (or covalent) functionalization, new functional groups are attached to the carbon atoms [107].…”

Density Functional Theory-Based Approaches to Improving Hydrogen Storage in Graphene-Based Materials

“…These structures are shown in Figure 1 . Although carbon structures are good candidates for hydrogen storage, pristine carbon structures have limited reactivity for hydrogen storage [ 42 , 43 ]. Therefore, to improve the hydrogen storage properties of these structures, diverse approaches such as defect engineering and surface functionalization have been implemented.…”

Stability, Energetic, and Reactivity Properties of NiPd Alloy Clusters Deposited on Graphene with Defects: A Density Functional Theory Study

“…However, it exhibits limited chemical reactivity [25,26]; to date, different strategies, such as defect engineering and surface functionalization, have been implemented to improve this issue [27]. Specifically, defect engineering (e.g., vacancy and doping) has proven to be an excellent method to increase the reactivity of carbon structures [27][28][29]. For example, pyridinic N-doped graphene (PNG) has proven to be a vital support material since it enhances the catalytic activity and stability of nanoparticles [30][31][32][33].…”