TiO<SUB>2</SUB> Particles on a 3D Network of Single-Walled Nanotubes for NH<SUB>3</SUB> Gas Sensors

Abstract

Ammonia (NH3) gas is one of the gases which causes damage to environment such as acidification and climate change. In this study, a gas sensor based on the three-dimensional (3D) network of single-walled nanotubes (SWNTs) was fabricated for the detection of NH3 gas in dry air. The sensor showed enhanced performance due to the fast gas diffusion rate and weak interactions between the carbon nanotubes and the substrate. Metal oxide particles were introduced to enhance the performance of the gas sensor. Atomic layer deposition (ALD) was employed to deposit the metal oxide in the complex structure, and good control over thickness was achieved. The hybrid gas sensor consisting of the 3D network of SWNTs with anatase TiO2 particles showed stable, repeatable, and enhanced gas sensor performance. The phase of TiO2 particles was characterized by Raman and the morphology of the TiO2 particles on the 3D network of SWNTs was analyzed by transmission electron microscope.

Adsorption, Dissociation, and Spillover of Hydrogen over Au/TiO2 Catalysts: The Effects of Cluster Size and Metal–Support Interaction from DFT

“…Titanium dioxide (TiO 2 ) has been widely used in the field of environmental protection and energy conservation such as photocatalysis, , heterogeneous catalysis, ,, gas sensors, − and dye-sensitized solar cells − due to its excellent photoelectric properties, nontoxic nature, physical chemical stability, high catalytic activity, and low costs. Au nanoparticles supported on TiO 2 have been widely used in many important catalytic reactions. ,− The structures of Au nanoparticles on TiO 2 have been studied using high-resolution electron microscopy (HREM), and researchers found that the catalytic activity strongly depends on the size of Au particles as well as the crystalline structure of TiO 2 supports. , Density functional theory (DFT) calculations were employed to investigate the interactions between Au and TiO 2 support − as well as the reaction mechanisms for reactions catalyzed by Au/TiO 2 catalysts. ,− Catalytic hydrogenation is an important type of reaction in which Au nanoparticles supported on TiO 2 exhibit their particular catalytic capability such as in CO 2 reduction, ,,− the hydrogenation of unsaturated C–C bonds, ,, the selective hydrogenation of α,β-unsaturated carbonyl compounds such as aldehydes and ketones, ,,− and the hydrodeoxygenation of biomass-derived compounds. ,,, In these hydrogenation processes, the adsorption and dissociation of hydrogen on the supported metal particles are crucial steps and sometimes rate-limiting .…”

Gas Biosensor Arrays Based on Single-Stranded DNA-Functionalized Single-Walled Carbon Nanotubes for the Detection of Volatile Organic Compound Biomarkers Released by Huanglongbing Disease-Infected Citrus Trees

“…To improve sensitivity and selectivity, biosensors that incorporate a variety of bioreceptors and transducers have been reported in the literature. SWNT surface can be functionalized/decorated with inorganic molecules (TiO 2 , SnO 2 nanoparticles) [24,25,26], organic macromolecules (porphyrin, polycyclic aromatic hydrocarbons) [27,28], or biomolecules [29] to improve the sensing performance. DNA molecules [30,31] are naturally occurring polymers that have many unique functions, including catalyzing chemical reactions [32] and controlling gene expression.…”