Abstract
The properties of multi-wall carbon nanotubes decorated with iridium oxide nanoparticles (IrOx-MWCNTs) are studied to detect harmful gases such as nitrogen dioxide and ammonia. IrOx nanoparticles were synthetized using a two-step method, based on a hydrolysis and acid condensation growth mechanism. The metal oxide nanoparticles obtained were employed for decorating the sidewalls of carbon nanotubes. Iridium-oxide nanoparticle decorated carbon nanotube material showed higher and more stable responses towards NH3 and NO2 than bare carbon nanotubes under different experimental conditions, establishing the optimal operating temperatures and estimating the limits of detection and quantification. Furthermore, the nanomaterials employed were studied using different morphological and compositional characterization techniques and a gas sensing mechanism is proposed.
Highlights
Chemical sensors employing carbon nanomaterials, like carbon nanotubes and graphene, have attracted great research interest
Despite the fact that carbon nanotube mats can work at room temperature for gas sensing [33], the presence of metal oxide nanoparticles, which may show catalytic properties above room temperature, has encouraged us to explore the performance of the hybrid nanomaterials at moderate operating temperatures
From the gas sensing tests, it was derived that the presence of iridium oxide (IrOx) NPs decorating the outer wall of multi-wall carbon nanotubes (MWCNT) was advantageous for detecting ammonia and nitrogen dioxide
Summary
Chemical sensors employing carbon nanomaterials, like carbon nanotubes and graphene, have attracted great research interest. Carbon nanotubes have been extensively employed in gas sensing applications due to their suitable electronic, physical, and chemical properties, such as nanometer-size, high carrier mobility, and surface area to volume ratio [1]. By functionalizing the sidewalls of multi-wall carbon nanotubes (MWCNT), some sensing properties can be enhanced, such as reproducibility, selectivity, and sensitivity [2]. Different options have been widely used to improve gas sensing performance, such as grafting functional groups onto the carbon nanotubes (CNT) surface [3] or decorating them with metal or metal oxide nanoparticles [4]. Even though many papers have been published on the attachment of metal or metal oxide nanoparticles on carbon nanotube sidewalls [4], to the best of our knowledge this is the first time that the decoration of carbon nanotubes with iridium oxide nanoparticles in chemoresistive gas sensing is studied. This paper reports the improvements obtained by loading MWCNTs with
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