Al and W co-doped NiO nanoflowers with low crystallinity and rich oxygen vacancies for high stability and selective triethylamine detection

In this work, pure NiO, Al-doped NiO, W-doped NiO and a series of Al/W co-doped NiO nanoflowers were successfully prepared through a simple solvothermal method. Various characterization methods, such as XRD, SEM, TEM, HRTEM and XPS, were used to confirm the physical and chemical properties of the sensitive materials in terms of micro-nano structures, compositions and elemental distributions. The as-obtained Al/W co-doped NiO showed a nanoflower structure with an approximate size of similar to 200 nm. What's more, among six sensors constructed from the sensitive materials, the sensor based on 3 at% Al3+/3 at% W6+ co-doped NiO (3Al3W-NiO) achieved the highest response (R-g/R-a=112) toward 100 ppm triethylamine with a low detection limit (1 ppm) at 325 degree celsius. Besides, this sensor also exhibited excellent response/recovery characteristics and long-term stability. These favorable sensing performances of the 3Al/3 W co-doped NiO sensor are not only modulated by the initial resistance (R-a), but are also closely related to the large specific surface area, porous structures, low crystallinity, rich oxygen vacancies and high Ni3+/Ni2+ ratio in the composite nanomaterials.