Single wall carbon nanotubes loaded with Pd and NiPd nanoparticles for H2 sensing at room temperature

Abstract

Pd and bimetallic Ni 50 Pd 50 nanoparticles protected by polyvinylpyrrolidone (PVP) have been synthesized by the reduction-by-solvent method and deposited on single wall carbon nanotubes (SWCNTs) to be tested as H 2 sensors. The SWCNTs were deposited by drop casting from different suspensions. The Pd nanoparticles-based sensors show a very reproducible performance with good sensitivity and very low response times (few seconds) for different H 2 concentrations, ranging from 0.2 to 5 % vol. H 2 in air at atmospheric pressure. The influence of the metal nanoparticle composition, the quality of SWCNTs suspension and the metal loading have been studied, observing that all these parameters play an important role in the H 2 sensor performance. Evidence for water formation during the H 2 detection on Pd nanoparticles has been found, and its repercussion on the behaviour of the assembled sensors is discussed.The sensor preparation procedure detailed in this work has proven to be simple and reproducible to prepare cost-effective and highly efficient H 2 sensors that perform very well under real application conditions. * Corresponding author. Fax: +34 965 903454 E-mail: a.berenguer@ua.es (Á. Berenguer-Murcia) 2 1. Introduction.

Enhanced ammonia-borane decomposition by synergistic catalysis using CoPd nanoparticles supported on titano-silicates

“…15,24 After their purification, the NPs were loaded on SiO 2 and Ti-SiO 2 (UV-Vis inactive and active supports, respectively) to study their catalytic activity in AB…”

“…22,23 In the present work, Pd and Co x Pd 1-x NPs were prepared by the well-established procedure of the reduction by solvent method using PVP as capping agent and following an already reported procedure. 15,24 After their purification, the NPs were loaded on SiO 2 and Ti-SiO 2 (UV-Vis inactive and active supports, respectively) to study their catalytic activity in AB Fig. 1).…”

Switchable Surfactant-Assisted Carbon Nanotube Coatings: Innovation through pH Shift

“…It should be noted, however, that the procedure described in this manuscript does not require a lengthy or aggressive treatment for the carbon nanostructures. In addition, the amount of surfactant used is almost two orders of magnitude lower than other reports in which CNT suspensions were obtained by the use of surfactants (Bravo-Sanchez et al, 2010;García-Aguilar et al, 2014). Considering that the concentration of the resulting suspensions is comparable to those reported in the literature, our approach to employ a pH-switchable surfactant opens up new possibilities in the field on CNT inks and thin films preparation.…”

“…Given their chemical nature, carbon-based nanomaterials show very poor dispersability in water. To overcome this problem, two main strategies have been reported in the literature: some authors have observed that the use of polymers, which combine a polar end (which may interact with water) with a non-polar end (which may interact with the carbon surface) in combination with a water-soluble polymer gives rise to stable suspensions of CNTs (or "inks," as the authors point out) (Bravo-Sanchez et al, 2010;García-Aguilar et al, 2014). On the other hand, and so as not to introduce a large amount of surfactant species in the suspensions, other authors have made use of the surface chemistry of carbon nanomaterials, modifying their functional groups with a strong acid such as HNO 3 or HNO 3 /H 2 SO 4 mixtures, which in turn led to the preparation of stable suspensions, which are pH sensitive.…”

“…To achieve this particular target, new strategies must still be developed in order to enable the generation of homogeneous coatings with the desired thickness throughout the microfluidic pipes without obstructing the system. Among the many applications, which are currently being explored for the implementation of carbon nanomaterials-based systems and devices, we may find the preparation of conducting fibers in order to improve their durability (Xiang et al, 2012), the development of laser-resistant coatings (Bhandavat et al, 2013), the fabrication of films for heat transfer enhancement (Sujith Kumar et al, 2014), or the synthesis of materials capable of acting as sensors (García-Aguilar et al, 2014) or biosensors (Papper et al, 2013). All these applications have in common that they require the deposition of a film or coating as homogeneous as possible on a suitable substrate, which in turn ultimately depends on the preparation of stable carbon nanomaterials suspensions.…”