Facile and single step synthesis of three dimensional reduced graphene oxide-NiCoO2 composite using microwave for enhanced electron field emission properties

We report the enhanced field emission properties of three-dimensional (3D) mixed transition metal oxide with reduced graphene oxide nanosheets (rGO-NSs) using a simple and fast synthesis route. The rGONSs with different/mixed transition metal oxide (rGO-MxOy) (MxOy = CoO, NiO and NiCoO2) composite has been synthesized for comparative studies for the electron field emission properties. The various rGO-MxOy composite materials were synthesized by microwave irradiation using soild precursor powder. The electron field emission properties were studied for all the samples as rGO-NSs, rGO-CoO, rGO-NiO and 3D rGO-NiCoO2 composite. It was found that specially, rGO-NiCoO2 composite shows the enhanced field emission performance due to synergic effect of mixed transition metal oxide as NiCoO2 nanoparticles with rGO-NSs and also the proper anchoring of NiCoO2 nanoparticles on rGO-NSs. The attachment of NiCoO2 mixed transition metal oxide with rGO-NSs exhibited lower turn-on field, lower threshold field, larger field enhancement factor and stable emission current stability as compared with those of the rGO-NSs, rGO-CoO and rGO-NiO composite. The surface microstructural analysis and morphology were probed by XRD, scanning and Raman. We suggest that anchoring of binary metal oxide nanoparticles on rGO-NSs could be exploited for the development of efficient field emitters. (C) 2017 Elsevier B.V. All rights reserved.