Effect of Capping-Agent Concentration on Size and Size Dispersity of Palladium Nanoparticles for Resistive-Type Hydrogen
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https://doi.org/10.1007/s11664-020-08431-0 2020 The Minerals, Metals & Materials Society
Effect of Capping-Agent Concentration on Size and Size Dispersity of Palladium Nanoparticles for Resistive-Type Hydrogen Sensors POOJA BHARDWAJ,1 P.B. BARMAN,1,2 and S.K. HAZRA1 1.—Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234, India. 2.—e-mail: [email protected]
The size attributes in palladium nanoparticle yield were found to influence the hydrogen sensor response in resistive devices, and the sensing mechanism was correlated with the variation of particle size from large to small in a particular synthesis product. The quantity of polyvinylpyrrolidone (PVP), the stabilizer used in this study, was varied during synthesis, and the resulting sizes were determined by high-resolution transmission electron microscopy (HRTEM). The size tuning by the capping agent PVP was also confirmed by UV–Vis spectroscopy via a detailed analysis of the experimental spectra, which revealed an interesting shift of the major absorption peaks with the increase in PVP. Glancing-angle x-ray diffraction (GAXRD) studies were undertaken to highlight the face-centred cubic crystallinity of the drop-cast nanofilms on thin glass substrates, as well as to evaluate the variation in crystallite cluster size by analyzing the major diffraction peaks. The size variation from HRTEM and GAXRD studies was found to match within the limits of experimental accuracy. The hydrogen sensor studies showed good room temperature response with typical size-dependent characteristics. The mechanistic control of the hydrogen activity over the mixed sized nano-films at room temperature (RT) and beyond RT is elaborately discussed. Key words: Palladium nanoparticle, size dependence, polydispersity, room temperature, hydrogen sensor
INTRODUCTION Studies with nanoparticles are receiving worldwide attention due to their extensive application potential. For instance, nanomaterial-based optical sensors are quite useful for medical devices, biofuels, and engineering applications.1–3 The potential for these nanomaterials can be further improved by tuning certain characteristic parameters. For instance, the size of nanomaterials is an important parameter that governs their activity. The particle size in the synthesized product is generally dependent on the methodology and the parametric
(Received December 26, 2019; accepted August 19, 2020)
control. The role of size in catalytic applications has been presented from different perspectives based on their method of synthesis.4–6 For instance, the potential for Pd nanoparticles of different sizes was demonstrated via their catalytic activity in C–C coupling reactions.7 In this regard, stabilizers are important components in nanoparticle synthesis (by the wet chemical route), as they control the size of the nanoparticles. Further, it is reported that surfactants can tune the particle size if the length of the surfactant molecule is varied.8 The size
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