H₂-TPR Application for Sensitivity Analysis of In₂O₃-Based Nanostructure Layers

The hydrogen temperature-programmed reduction (H₂-TPR) method was used to analyze the sensing properties of nanostructured indium oxide for hydrogen detection. Commercial and mechanically activated In₂O₃ samples were selected for investigation. Mechanical activation leads to the generation of surface defects and an increase in specific surface area, which enhances sensitivity to H₂ and lowers the sensor operating temperature. An approach is proposed that allows a qualitative and quantitative relationship to be established between the H₂-TPR profiles of the oxides and the sensor response. This relationship is based on a model of electron transfer across a potential barrier at grain boundaries, formed with the participation of adsorbed oxygen. The temperature dependence of the sensor response is found to be determined by the concentration of negatively charged oxygen on the surface of the nanoparticles, which, in turn, depends on temperature. Using the sensor sensitive layer based on indium oxide as an example, a correlation is established between the parameters of the TPR profiles and the sensor response.