Recent Advancements in TiO2 Nanostructures: Sustainable Synthesis and Gas Sensing

Abstract

The search for sustainable technology-driven advancements in material synthesis is a new norm, which ensures a low impact on the environment, production cost, and workers’ health. In this context, non-toxic, non-hazardous, and low-cost materials and their synthesis methods are integrated to compete with existing physical and chemical methods. From this perspective, titanium oxide (TiO2) is one of the fascinating materials because of its non-toxicity, biocompatibility, and potential of growing by sustainable methods. Accordingly, TiO2 is extensively used in gas-sensing devices. Yet, many TiO2 nanostructures are still synthesized with a lack of mindfulness of environmental impact and sustainable methods, which results in a serious burden on practical commercialization. This review provides a general outline of the advantages and disadvantages of conventional and sustainable methods of TiO2 preparation. Additionally, a detailed discussion on sustainable growth methods for green synthesis is included. Furthermore, gas-sensing applications and approaches to improve the key functionality of sensors, including response time, recovery time, repeatability, and stability, are discussed in detail in the latter parts of the review. At the end, a concluding discussion is included to provide guidelines for the selection of sustainable synthesis methods and techniques to improve the gas-sensing properties of TiO2.

Nb2O5 Microcolumns for Ethanol Sensing

“…To evaluate the sensor’s response to n-type behavior, the conductance of the sensor was compared under two conditions: firstly in the presence of the target gas, and secondly in synthetic air. The sensor’s response was quantified using the equation S (∆G/G) = (G g − G a )/Ga for reducing gases or (G a − G g )/G g for oxidizing gases, where G a represents the conductance of the sensor in synthetic air and G g corresponds to the conductance of the sensor when exposed to the analyte gas [ 18 , 29 ]. This approach allowed for the characterization of the sensor’s performance in detecting and distinguishing between different gases, providing valuable insights into its sensitivity and selectivity.…”

“…By detecting the presence of ethanol in the air, these sensors can alert workers to impending dangers, safeguarding them from potential adverse effects such as irritations of the eyes, nose, and throat, as well as inducing headaches, dizziness, and even unconsciousness [ 12 ]. Consequently, ethanol gas sensing has emerged as a subject of utmost significance, garnering considerable attention in recent years, as evidenced by numerous scholarly works [ 13 , 14 , 15 , 16 , 17 , 18 ].…”

A Mini-Review on Metal Oxide Semiconductor Gas Sensors for Carbon Monoxide Detection at Room Temperature

“…Moreover, porous TiO 2 was reported to be suitable for chemical sensors in cyber chemical systems [70]. The latest progress in TiO 2 nanostructures for gas sensing can be found in another review [71]. WO 3 is an excellent material for CO sensing as well [72,73].…”

Photocatalytic TiO2-Based Nanostructures as a Promising Material for Diverse Environmental Applications: A Review

“…The band-gap within titanium dioxide originates from the arrangement of electrons in both Ti and O atoms. Across all three polymorphs of titanium dioxide, the valence band (VB) mainly comprises O 2p orbitals, while the conduction band (CB) primarily consists of Ti 3d orbitals [47,48]. The most increased point of the VB resides at the Γ point within the Brillouin zone, while the lowest point of the CB sits at the X point.…”