Fabrication of Ni-NiO@polyaniline for highly selective and fast room-temperature NH3 sensing: p-n response transition based on heterogeneous interface engineering

Developing highly selective and fast NH 3 gas sensors operable at room temperature (RT) has significant application value but remains challenging. Herein, Ni-NiO@polyaniline (PANI) nanocomposites (NNOPs) were fabricated by thermal treatment of Ni foam and in situ polymerization of aniline. NNOPs exhibit p-n response transitions and rapid response rates to NH 3 at room temperature under varying amounts of PANI loading. The maximum response to 100 ppm NH 3 is 143.7 % and the response/recovery time was 22/40 s, which is 3181 % shorter than the response time of pure PANI (700 s). The unique response transition can significantly enhance the selectivity of NH 3 sensing. Additionally, NNOPs also demonstrate excellent repeatability, long-term stability, and humidity insensitivity. The outstanding sensing performance can be attributed to the ohmic contact between Ni and NiO, the oxygen vacancies induced by PANI surface modification and the large specific surface area. The high selectivity and fast NH 3 response of NNOPs sensors at RT hold great value for applications in fields such as internet of things and flexible electronics. • Ni-NiO@polyaniline was fabricated for trace NH 3 sensing at room temperature. • The composite of PANI can induce the generation of oxygen vacancies in NiO. • Ni-NiO@PANI exhibits concentration-dependent p-n response transitions for NH 3 . • The response speed is 3181 % faster than that of pure PANI.