Computational assisted tuning of Co-doped TiO2 nanoparticles for ammonia detection at room temperatures
Résumé
Improved gas sensors based on pure anatase TiO 2 and Co-doped TiO 2 nanoparticles were evaluated. A cobalt- doped TiO 2 nanoparticle with a diameter of 40 nm was first synthesized. The morphology of the nano particles was analyzed by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The doped Co ion was confirmed to have entered the TiO 2 lattice. Subse quently, gas sensors with different Co-doping concentrations were developed to investigate gas sensitivity to NH 3 . Compared with pure anatase TiO 2 operating at 180 ◦ C, Co-doped TiO 2 samples were developed as NH 3 gas sensors operating at room temperature. The 20% Co-doped sample exhibited the best performance, with a response value of 14 for 50 ppm NH 3 , which was 7 times higher than that of pure TiO 2 . The response and re covery times of the sensor were only 25 and 48 s, respectively, and exhibited both good stability and selectivity. Based on density functional theory (DFT), the calculated bandgap of Co-doped TiO 2 decreased by 72% compared to pure TiO 2 . Structural simulation and mechanism analysis elucidated the good gas-sensing performance at room temperature and the property enhancement of the Co-doped TiO 2 gas sensor.