Hydrogen sensors with high humidity tolerance based on indium-tin oxide colloids

Hydrogen sensing in real environments is an important issue on the pathway toward the hydrogen economy. The use of semiconductor-based sensing layers has significantly advanced the detection limit of the H₂ sensor, in part thanks to the additional use of catalytic metals which effectively dope their electron depletion layer. Nevertheless, these high-end sensors are highly sensitive to the environmental parameters (temperature and humidity) and require a complex fabrication process. Herein, we report a colloidal approach to the fabrication of indium-tin oxide combined with palladium-nickel or platinum nanoparticles sensing layer. The cross-sections of the sensing layers show the network of nanoparticles and voids responsible for the excellent sensing properties they display. The sensors show sensitivity from 4 % down to 70 ppm of H₂ and repeatability in that range. Moreover, the sensors have a unique ability to be tolerant to the humidity level with similar sensing response whatever the humidity level in the broad range from 0 to 60 % relative humidity. This tolerance is attributed to the organic layer coating the nanoparticles.