Highly-sensitive H2 sensor operating at room temperature using Pt/TiO2 nanoscale Schottky contacts

•A metal oxides-based H2 sensor operating at low temperature has been demonstrated.•Pt/TiO2 nanoscale Schottky contacts facilitate H2 diffusion and dissociation.•Sensing mechanism is contact-dominant at low T, while surface-dominant at high T.•Oxygen plays an important role for the recovery process. Despite growing demands for high performance hydrogen (H2) sensors operating at low temperature, metal oxides-based H2 sensors intrinsically require an elevated operating temperature due to a high activation energy for gas adsorption on metal oxides surface. Here, we present a highly-sensitive H2 sensor operating even at room temperature, enabled by the Pt/TiO2 nanoscale Schottky contacts which utilizes sensitive modulation of the Schottky barrier height by dissociative H2 adsorption on the catalytic Pt layer, followed by the dipole layer formation at the junction. Our device showed very high H2 response and short response and recovery times at low temperatures which are attributed to the unique device architecture having the highly-porous nanoscale Schottky contacts facilitating the gas diffusion and dissociation, and the top-and-bottom electrodes configuration making effective current modulation. Based on our results, we propose Schottky contact-assisted H2 sensing mechanisms and a promising approach to further improve H2 sensing performance at room temperature.