ZIF-67-derived NiCo2O4/NiO hollow nanocages decorated with Ag nanoparticles for humidity tolerance and high sensitivity n-butanol sensing

Nowadays, designing sensing materials possessing both high sensitivity and humidity resistance is still a challenge in the field of sensing materials. In this work, a ternary Ag nanoparticles decorated NiCo 2 O 4 /NiO (Ag/NiCo 2 O 4 /NiO) composite with hollow nanocage structure has been successfully obtained, which uses ZIF-67 as a template combined with self-etching method, followed by NaBH 4 reduction of silver ions. For the synergistic effect of the novel morphology, the presence of Ag nanoparticles and hydroxyl absorbent NiO, and the formation of p-p heterojunction between NiCo 2 O 4 and NiO, Ag/NiCo 2 O 4 /NiO exhibits good humidity resistance and high-sensitive to n-butanol. The mesoporous hollow nanocage morphology not only provides abundant adsorption sites for target gases, but also facilitates the diffusion of water molecules. The doping of Ag nanoparticles can regulate the adsorption of oxygen on the surface of gas sensing materials, improving the sensitivity while suppressing the hydroxyl poisoning reaction process. The hydroxyl absorbent NiO in Ag/NiCo 2 O 4 /NiO can both directly absorb water and form p-p heterojunction structure with NiCo 2 O 4 , which improves sensor performance while suppressing hydroxyl poisoning. In the gas sensing tests, the optimal Ag/NiCo 2 O 4 /NiO composites can achieve a high response value of 31.41, as well as rapid response/recovery times (65 s/47 s) to 100 ppm n-butanol at the working temperature of 170 °C. Moreover, it displays a wide detection range (1–120 ppm), a low detection limit (0.27 ppm), excellent selectivity to n-butanol, and superior long term stability (maintaining a response value of 84.68 % after 14 days). Notably, the optimal Ag/NiCo 2 O 4 /NiO demonstrates great humidity-tolerant ability with a response values fluctuation of 16 % under the range of 33 %-80 % relative humidity. This research provides a feasible approach for designing practical gas sensing materials with high sensitivity and moisture resistance.