TG/DTA of hydrogen reduction kinetics of TiO2 supported PdO chemochromic pigments

Titania supported palladium oxide (PdO) chemochromic pigments have been used in various hydrogen sensing devices as a passive technique for detecting hydrogen leaks. Here, we present new data for the kinetics of titania-supported PdO reduction by hydrogen gas by means of thermogravimetric/differential thermal (TG/DTA) analysis. The TG/DTA thermograms show a two step process. The first step in the process is an induction period during which no color change occurs – having zero reaction order with respect to palladium oxide concentration [PdO]. A color change is associated with the second step during which the adsorbed hydrogen reacts with PdO⋯H species to form water. This step has fast kinetics with reaction order of 0.55 and zero with respect to [PdO⋯H] and [H2], respectively.

► PdO/TiO2 chemochromic pigments as hydrogen sensor.
► Reduction proceeds in two stages.
► First stage is the induction period and the rate limiting step.
► Induction period is a zero order event with respect to PdO concentration.
► Color change occurs during the second stage.