Hydrogen sensing and adsorption kinetics on ordered mesoporous anatase TiO2 surface

Abstract

Employing TiO2 as a gas sensing material is advantageous owing to its excellent hydrogen surface receptiveness and stability under extreme conditions. However, their commercial applications are constrained by limited operating temperature range (150–400 °C) and poor selectivity. In this work, we demonstrate that the ordered mesoporous structured TiO2 is highly favourable for room temperature hydrogen sensing. The sensors prepared with evaporation induced self-assembly (EISA) showed best response ~2.98 × 102 toward 1000 ppm H2 at room temperature with a sensitivity of ~4.6 ± 1.5 × 106 ohm/ppm. Moreover, the sensor showed a response time of ~85 s (recovery time of ~198 s) with full baseline recovery and a selectivity factor of ~290 to 1000 ppm of interfering reducing gases CO and CH4 at room temperature. With a power consumption of ~1 × 10−9 W the sensors are incredibly suitable for practical applications. We performed XRD, SEM, TEM, XPS, BET and PL characterization not only to confirm the crystal structure, morphology at nanoscale, surface chemical identification, specific surface area, pore size and photo-generated charge species that contribute to the electronic transport properties but sensing mechanism also.