Hybrid Cr/TiO2/ITO nanoporous film prepared by novel two step deposition for room temperature hydrogen sensing

Highlights: • Room temperature hydrogen sensing performance of hybrid Cr:TiO₂/ITO nanocomposite was studied. • Different Cr deposition time played a major role on the properties of the sensor. • SEM revealed a nanospherical morphology for the hybrid Cr/TiO₂/ITO. • High sensor response and fast recovery was recorded even at low H₂ concentration. -- Abstract: In this work, catalytic Cr metal overlayered TiO₂/ITO nanocomposite films were synthesized by novel two step deposition using spray pyrolysis and electron beam evaporation and optimized for use as H₂ sensors. The Cr stimulated TiO₂/ITO sensor showed well-defined crystalline (101) TiO₂ anatase phase with crystallite size in the range 12–14 nm. The band gap energy could be tuned from 2.44 eV to 2.06 eV, when the thickness of Cr stimulating layer increased. The anatase phase of the nanocomposites was further confirmed by Raman spectroscopy. The nanospheres shaped grains with porous morphology of the film prepared for 10 min Cr deposition time is beneficial to enhance the gas sensing activity at room temperature. The nanocomposite sensor with different Cr overlayer thickness modified the TiO₂ microstructure due to spillover effect and revealed improvement in sensitivity. The Cr:TiO₂/ITO sensor prepared with the Cr deposition time of 10 min recorded a fast response and recovery time of 30 s and 20 s, respectively, even at room temperature.