Construction of trace nitric oxide sensors at low temperature based on bulk embedded BiVO₄ in SnO₂ nanofibers with nano-heterointerfaces

Constructing heterostructures is an effective way to improve the carrier mobility for metal oxide sensing material, since heterojunctions are usually built only on the surface of the material, the carrier transport efficiency inside the material still needs to be improved. In this paper, BiVO₄ nanocrystals (BVO NCs) with an average size of 1 nm generated by pulsed laser irradiation were embedded in situ at the particle boundaries (PBs) of SnO₂ nanofibers to form an effective n-n heterojunctions inside the material. After embedding the BVO NCs in the SnO₂ samples, the response value for 10 ppm NO was improved to 48.91, which was 2.5 times higher than that of pure SnO₂ at near room temperature (50 °C). Meanwhile, the detection limit was lowered to 50 ppb with excellent long term stability. Detailed analysis and theoretical calculations demonstrated that the formation of abundant n-n heterojunctions not only promotes the electron-hole separation and the carrier mobility, but also reduces the conductivity and adsorption energy of the material, which significantly improves its sensing performance. This work demonstrates a new approach to modulate the gas-sensing performance of metal oxide semiconductors by generating heterostructure inside the bulk of the material.