Highly sensitive hydrogen sensor based on nickel incorporated TiO2 nanostructures operating at room temperature

Abstract

We demonstrate the effect of nickel doping on the sensing performance of TiO2 nanospheres towards hydrogen at room temperature. A novel microwave assisted processing was adopted for the synthesis of Ni:TiO2 nanospheres. The preferential (101) anatase phase of TiO2 changed to anatase–rutile mixed phase after Ni doping. The vibrational spectra show significant shift in the peak with catalytic Ni addition. The energy gap of TiO2 increased with Ni incorporation from 3.28 to 3.35 eV due to size confinement. Photoluminescence analysis confirmed the decreased intrinsic defect density in Ni doped TiO2 nanostructures. The morphology of Ni:TiO2 demonstrated nanospherical shaped grains with increased porosity favorable for sensing. The resistance of Ni:TiO2 sensors fabricated with a multi-terminal network H2 adsorption layer improved dramatically to 1100 MΩ, compared to 600 MΩ recorded for pristine TiO2. The nanocomposite sensor showed fast recovery of 40 s, to even a low concentration of 100 ppm H2 at room temperature.