Small size porous NiO/NiFe2O4 nanocubes derived from Ni-Fe bimetallic metal-organic frameworks for fast volatile organic compounds detection

Despite the vital role of heterojunction construction in optimizing the performance of the MOS-based gas sensor, the one-step synthesis of uniformly dispersed miniaturized heterostructures remains a challenge. In this study, bimetallic MOFs Ni-Fe PBA of small size (about 75 nm) was prepared by a simple coprecipitation method. Taking it as the self-sacrificial model, we obtained NiO/NiFe2O4 nanocubes with porous, small-sized, uniform distributed heterostructure (about 56 nm). The gas-sensitive test results show that the NiO/NiFe2O4 materials exhibit ptype gas-sensitive behavior and have good gas-sensitive property to a wide range of volatile organic compounds (VOCs) gases (acetone, ethyl acetate, aniline, triethylamine, ethanol, formaldehyde, toluene, and trimethylamine). In particular, the NiO/NiFe2O4 sensor has fast response/recovery characteristics to 100 ppm VOCs gases at low operating temperature (170 celcius), and the response/recovery times of several representative VOCs such as acetone, ethyl acetate, triethylamine and toluene were 12.8 s/15.6 s, 26 s/15.8 s, 11.2 s/14.4 s, 19.6 s/31.8 s, respectively. The superior response of porous NiO/NiFe2O4 nanocubes towards VOCs is attributed to the large specific surface area of the porosity and the uniformly dispersed heterostructure, which facilitate gas transport and exposure of active sites.