ZnNi(NA) (NA= Nicotinic acid) bimetallic mesoporous MOFs as a sensing platform for ethanol, formaldehyde and ammonia at room temperature

A novel bimetallic ZnNi(NA) (NA = Nicotinic acid) MOF nanomaterials with molar ratios of 3:1; 1:1; and 1:3 are deployed as sensing materials for detection of NH3, HCHO and C2H5OH vapours at room temperature. These metal-organic frameworks (MOFs) were synthesized in 3:1 methanol and water solvents at 130 degrees C by solvothermal method. Several characterization techniques, like XRD, FT-IR, SEM, EDS, elemental analysis, TGA, and XPS, are used for structural illustration. Zn/Ni bimetallic MOFs exhibited smaller particle sizes and superior surface areas compared with Zn(NA) and Ni(NA) monometallic MOFs. ZnNi(NA)-1:1 showed a microporous nature, while ZnNi(NA)-3:1, ZnNi(NA)-1:3 and Zn(NA) are mesoporous nature. All the materials exhibited good thermal stability up to 450 degrees C temperature. The sensor-based on porous ZnNi(NA)-1:1 nanomaterial (approximate to 2.4 nm) exhibits the best sensing performance towards ammonia at 50 ppm concentration. The ZnNi(NA)-1:1 material showed more response (R-a/R-g = 291) compared to the monometallic compounds Ni(NA) (R-a/R-g = 119) and Zn (NA) (R-a/R-g = 64). All sensors have good reproducibility and excellent long-term stability.

Automated summary

A novel bimetallic ZnNi(NA) MOF nanomaterials were synthesized and used for the detection of NH3, HCHO and C2H5OH vapours. The characterization techniques revealed that the bimetallic MOFs had smaller particle sizes and larger surface areas compared to monometallic MOFs. Among them, ZnNi(NA)-1:1 nanomaterial exhibited the best sensing performance towards ammonia.