Sensing Behavior of Room Temperature Amperometric H₂Sensor with Pd Electrodeposited from Ionic Liquid Electrolyte as Sensing Electrode

Abstract

A fuel cell based amperometric room temperature hydrogen sensor with Nafion as proton conducting electrolyte, Pd as sensing electrode, Pt as both counter and reference electrodes has been developed. Sensing electrode was prepared by electrodeposition of Pd on carbon gas diffusion electrode using room temperature ionic liquid electrolyte. Pt spray coated on gas diffusion electrode forms the counter electrode in the sensor. Pd electrodeposition was carried out at an applied potential of −1.0 V vs Pd wire and resulted in the formation of Pd clusters. The microstructure of electrodeposited Pd was investigated using field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The crystal structure of the Pd nanoparticles was indexed to face centered cubic by X-ray diffraction (XRD) and selected area electron diffraction (SAED). X-ray photoelectron spectroscopy (XPS) confirmed metallic form of the deposited Pd nanoparticles. The scratch test endorsed the fact that Pd nanoparticles adhered firmly to the surface of the gas diffusion electrode and it is found to be stable up to the load of 2 N. Range of response of the sensor to H 2 was in the concentration range 1% to 5% and found to be linear.

Proton Exchange Membrane Fuel‐Cell‐Based Amperometric H2 Sensor with Pulsed Electrodeposited Electrodes Prepared Using an Ionic Liquid Electrolyte

“…The long‐term stability of the sensor was studied by recording the sensor signal for two weeks, and the plot is shown in Figure (b). Improved sensor performance owing to the use of RTILs has been observed and reported in the literature ,…”

“…Electrodeposition and pulsed electrodeposition using ionic liquid electrolyte give better adhesion of the catalyst onto the support. This improves the three phase contact between reactant, electrode and electrolyte which decides the integrity of the catalyst onto the support …”

“…Subsequently, they observed Pt electrodeposited from RTIL exhibited a superior catalytic performance to its aqueous counterpart owing to the higher catalytic surface area. In our previous work, we reported Pd electrodeposition over GDE in RTIL ([C4mim][Cl]) medium towards H 2 sensing . In that work, we ascertained that the RTIL aided superior adhesion of the Pd electrocatalyst on to the substrate which in turn increased the life time of the sensor.…”

“…These limitations of aqueous electrolytes affect its application although it has an advantage with respect to conductivity, mass transfer and cost. Hence, non‐aqueous electrolytes have become an alternative to aqueous electrolytes . Room temperature ionic liquids (RTIL) find applications in electrochemistry, organic synthesis, separations, etc.…”

“…Hence, non-aqueous electrolytes have become an alternative to aqueous electrolytes. [17] Room temperature ionic liquids (RTIL) find applications in electrochemistry, organic synthesis, separations, etc. RTIL also acts as a template for preparing metal nanoparticles [18,19] and have become increasingly important electrolyte media for electrodeposition because of its high electrochemical window, low vapour pressure and high ionic conductivity.…”