Pyramid-shaped MMn2O4/rGO (M = Ni, Co) nanocomposites and their application in ammonia sensors

Abstract

Herein, the MMn2O4 and MMn2O4/rGO (M = Ni, Co) samples were synthesized using co-precipitation and wet impregnation methods. XRD analysis showed the high purity and good crystallinity of the synthesized powders. FESEM analysis revealed the formation of pyramid-like structures and a good intimate mixture with rGO in the nanocomposite samples. Gas sensors were fabricated with pure and nanocomposite structures for the sensing of ammonia gas. The CoMn2O4/rGO nanocomposite sample achieved a higher sensitivity (S = 3.5) with shorter response/recovery (140 s/83 s) behavior in room temperature at 100 ppm of NH3. The stability and selectivity of the CoMn2O4/rGO nanocomposite gas sensor were examined. The preferable sensing mechanism of CoMn2O4/rGO nanocomposite towards the detection of NH3 was discussed.