Pd Nanoparticles and Thin Films for Room Temperature Hydrogen Sensor

Abstract

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 H2sensing 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 H2sensing 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. H2sensing by the Pd nanostructures is attributed to the chemical and electronic sensitization mechanisms.

Transmission electron microscopy studies of the Pd–C films obtained by physical and chemical vapor deposition

“…The PVD/CVD was covered with a layer of porous carbon and create a filter for some compounds, such as CO. For hydrogen, such coating does not be barrier but compounds such as carbon monoxide have difficult access to parts of the palladium films. It can be important for sensor functioning in an atmosphere such as CO, which poisons the detector and usually gives changing the electrical conductivity of the active layer [27,32,33]. …”

“…Porous carbon has a high specific surface area [23], which suggests that the combination of these characteristics will significantly increase the possibilities of detection and makes these films ideal sensors of the hydrogen. It also showed that the nanocrystalline palladium can absorbs hydrogen [24,25], it can show a change in crystal structure [26] and in electrical conductivity [27] in hydrogen presence.…”

Hydrogen gas sensors based on electrostatically spray deposited nickel oxide thin film structures

“…Another third port was provided for vacuum gauge connection. A multi-pin feedthrough at the base of the chamber allowed for the electrical connections to be established to the heater assembly as well as to the sensor electrodes via spring loaded pins [19][20][21].…”

The electrical characterization and response to hydrogen of Schottky diodes with a resistive metal electrode—rectifying an oversight in Schottky diode investigation

“…In thinking about how these results relate to previous Schottky diode-based hydrogen detectors we consider the response time, sensitivity and other features. First of all, the initial time response is slow, as is the case with some other investigations using Schottky diodes [31,32,54], and even some work on hydrogen detection using Pd nanoparticles and thin films [55], but once the detector has been 'sensitized' the response to subsequent changes in hydrogen level is somewhat faster, on the scale of minutes. There are two aspects to the slow initial response, the first being that hydrogen must reach the SB interface region where it interacts to cause a lowering of the barrier.…”