Three-in-one Ni doped porous SnO2 nanorods sensor: Controllable oxygen vacancies content, surface site activation and low power consumption for highly selective NO2 monitoring

Introducing oxygen vacancies and surface site activation is an effective method to enhance metal oxide gas sensing. However, the regulation of oxygen vacancy concentration within metal oxides and the controllable design of surface sites activation under mild conditions are critical but challenging techniques. Here, we demonstrate a simple and efficient solvothermal concomitant annealing method to obtain Ni doped SnO2 nanorods with controllable oxygen vacancies content, surface sites activation and unique morphology. The 10% Ni doped SnO2 nanorods sensor showed excellent trace NO2 sensitivity at low power consumption, and lowest detection limit is 20 ppb, which is nearly 4 times lower than that of pure SnO2. DFT calculation showed that the bridging oxygen vacancies as the main surface site activation and facilitate the adsorption of NO2, thereby significantly improved the NO2 sensitivity. This work undoubtedly opens up new avenue to exploring and designing advanced metal oxide sensitive materials with controllable oxygen vacancy concentration and surface sites activation.