Electrodeposition and characterization of palladium nanostructures on stainless steel and application as hydrogen sensor (original) (raw)
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Journal of Power Sources, 2009
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Nanocrystalline Palladium Thin Films for Hydrogen Sensor Application
Sensor Letters, 2009
We report the application of palladium nanoparticles and thin films for hydrogen sensor. Electrochemically grown palladium particles with spherical shapes deposited on Si substrate and sputter deposited Pd thin films were used to detect hydrogen at room temperature. Grain size dependence of H 2 sensing behavior has been discussed for both types of Pd films. The electrochemically grown Pd nanoparticles were observed to show better hydrogen sensing response than the sputtered palladium thin films. The demonstration of size dependent room temperature H 2 sensing paves the ways to fabricate the room temperature metallic and metal-metal oxide semiconductor sensor by tuning the size of metal catalyst in mixed systems. H 2 sensing by the Pd nanostructures is attributed to the chemical and electronic sensitization mechanisms.
Journal of Physics D: Applied Physics, 2011
This study reports a promising, cost-effective nanoscale hydrogen sensor fabricated using the dielectrophoresis (DEP) process. Palladium nanoparticles (NPs) of diameter in the range 2-4 nm were assembled in a 20 nm gap between electrodes under optimized DEP parameters of frequency, voltage and assembling time of 1 M Hz, 1.5 V and 90 s, respectively. The fabricated nanoscale device was powered by applying a dc voltage of 10 mV across nanogap electrodes and temporal change in resistance at an operating temperature of 160 • C was recorded in the presence of 3000 ppm of hydrogen gas. A rise and recovery times of 100 s and 300 s, respectively, in the temporal hydrogen gas response characteristic were observed which could be attributed to the hydride formation due to the strong affinity of assembled palladium NPs towards hydrogen. The nanoscale device was sensitive enough to respond to hydrogen presence even at 30 • C. Preliminary results show the potential of DEP in fabricating cost-effective nanoscale hydrogen sensor.
Role of Capping Agent in Palladium Nanoparticle Based Hydrogen Sensor
Journal of Cluster Science, 2018
Palladium (Pd) nanoparticles (NPs) were synthesized via polyol route by varying concentration of capping agent, polyvinylepyrollidone (PVP). High resolution TEM study showed that the palladium nanoparticles were nearly spherical shape in the size range 11-13 nm. Hydrogen response pattern of the devices fabricated with the synthesized Pd NPs were recorded and were found to vary with the concentration of PVP. Also, response magnitude increased with PVP concentration for a particular pattern. Smooth recovery was observed both with and without the flow of carrier gas. While the sensor performance was found to be best at room temperature, the device performance deteriorated with the increase in temperature. Excellent long-term stability was observed as the devices showed similar response after 30 days of testing. The reproducible hydrogen response of these devices was supported by X-ray diffraction studies done on samples before and after hydrogen sensor study. The variation in response with the concentration of PVP is corroborated with a suitable sensing mechanism.
Pd Nanoparticles and Thin Films for Room Temperature Hydrogen Sensor
Nanoscale Research Letters, 2009
We report the application of palladium nanoparticles and thin films for hydrogen sensor. Electrochemically grown palladium particles with spherical shapes deposited on Si substrate and sputter deposited Pd thin films were used to detect hydrogen at room temperature. Grain size dependence of H 2 sensing behavior has been discussed for both types of Pd films. The electrochemically grown Pd nanoparticles were observed to show better hydrogen sensing response than the sputtered palladium thin films. The demonstration of size dependent room temperature H 2 sensing paves the ways to fabricate the room temperature metallic and metal-metal oxide semiconductor sensor by tuning the size of metal catalyst in mixed systems. H 2 sensing by the Pd nanostructures is attributed to the chemical and electronic sensitization mechanisms.
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Molecular Crystals and Liquid Crystals, 2005
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This paper reports on miniaturized hydrogen sensing platforms, exploring several means of fabricating nanostructured films and evaluating their sensing characteristics. Palladium-sputtered nanoporous organosilicate matrices are fabricated using the polymeric system [polymethylsilsesquioxane (PMSSQ); polypropylene glycol (PPG); propylene glycol methyl ether acetate (PGMEA)] followed by volatilization of the liquid phase, i.e., PGMEA and PPG at their boiling points. In order to provide greater adsorption/desorption sites for the test gas, ultra-dense ZnO nano-brushes with very high aspect ratios are successfully fabricated in the porous template. Thereafter, functionalization of ZnO is performed by sputter coating thin Pd films onto the ZnO surface. Intensive characterization for these nanostructures is performed using FESEM, EDAX, FTIR, TEM and AFM techniques. Comparison of all fabricated sensing platforms for hydrogen gas-dependent responses based on temperature, as well as test gas concentrations at various ppm levels, is performed. Palladium coating of ZnO nano-brushes renders this film highly selective to hydrogen and also improves its sensitivity by a factor of ~66% relative to the uncoated film. Sensitivity to hydrogen is found to be ~70% and a selectivity test is performed with CO 2 and CH 4, with sensitivities of 5% and 7%, respectively. Pd-functionalized ZnO nano-brushes display enhanced hydrogen response behaviour.
A Single Palladium Nanowire Via Electrophoresis Deposition Used as a Ultrasensitive Hydrogen Sensor
IEEE Transactions on Nanotechnology, 2008
We have successfully fabricated and demonstrated the use of a single metallic nanowire as a hydrogen sensor with extremely high sensitivity via a very simple fabrication process. In this paper, single palladium (Pd) nanowires were electrodeposited within 100-nm-wide polymethylmethacrylate nanochannels using a Pd electrolyte solution. Via this method, nanowires were grown with widths ranging from 50 to 100 nm, and lengths from 3 to 7 µm. The nanowires were successfully used to sense hydrogen concentrations as low as 5 ppm at room temperature. The growth control of single Pd nanowires, as well as the primary sensing mechanism, is addressed in detail in this paper.
Shape dependent hydrogen response in palladium nanoparticle based sensors
Materials Today: Proceedings, 2020
Palladium nanoparticles (Pd NPs) with well-defined shape and controllable size were synthesized by Polyol strategy and the shape effect on hydrogen sensing at room temperature (RT) and beyond RT was detected. The evolution of shape in Pd NPs was dependent on the amount of stabilizer [Polyvinylpyrrolidone (PVP)] used during synthesis. Further, the dominant morphological facet in a particular shape determined whether the material will be suitable for room temperature or high temperature applications. The particle shape and facet hierarchy were analyzed using High Resolution Transmission Electron Microscopy (HRTEM) images, and Selected Area Electron Diffraction (SAED) patterns respectively. The hydrogen sensor studies revealed good response characteristics and the response parameters varied with the change in shape/facet characteristics of Pd nanoparticles. Also the variation of the hydrogen response with the increase in operating temperature was different for different shapes.
Hydrogen sensing performance of electrodeposited conoidal palladium nanowire and nanotube arrays
Sensors and Actuators B-chemical, 2009
Conoidal palladium nanowire and nanotube arrays were fabricated by electrochemical deposition into the branched pores of an alumina template. The formation of nanostructures was controlled by analysing current-time transients during electrodeposition. The sensor response to hydrogen gas was investigated in the arrays of just formed nanotubes and nanowires. The dominant sensing signal was increment of conductivity due to the contact improvement by volume expansion of nanowires and nanotubes. Without proper activation treatment, however, the sensing signal was not stable. A few cycles of hydrogen loading-unloading on the conoidal nanotubes dramatically enhanced the stability in hydrogen sensing performance. It was based on the formation of break junctions after exposure of conoidal palladium nanotubes to 1-2.5% H 2 , which also leaded to fast response on hydrogen concentration as small as 0.1% and small relaxation time when hydrogen was released.