Mesoporous nickel cobalt hydroxide/oxide as an excellent room temperature ammonia sensor

We report an excellent room temperature NH3 gas sensing performance using highly mesoporous nanoflakes of Ni-Co hydroxide/Oxide synthesised by facile and economical wet chemical method. The dynamic sensing of NiCo2(OH)6(NCH) and NiCo2O4 (NCO) shows nearly 3 and 2 fold increase in sensitivity by varying NH3 concentrations demonstrating excellent sensitivity which is in accordance to Freundlich equation. The interesting behaviour of NCO being p–type material spectacles n-type gas sensing behaviour towards low ammonia concentration at RT. The anomalous sensing response is ascribed to transition of majority charge carriers due to surface reaction of chemisorbed oxygen ions and ammonia gas vapours.