Conversion of pyrazoline to pyrazole in hydrazine treated N-substituted reduced graphene oxide films obtained by ion bombardment and their electrical properties

An efficient method for the conversion of pyrazoline to pyrazole in hydrazine treated N-substituted reduced graphene oxide (N-rGO) films at room temperature has been reported. This method comprises the Ar+ ion bombardment of the N-rGO films that are prepared by drop casting method. The X-ray photoelectron spectroscopy (XPS) data in association with the X-ray diffraction, Ultra-violet spectroscopy and Raman spectroscopy data reveal that the addition of hydrazine removes the epoxy and hydroxyl groups of graphite oxide largely, and the reaction of hydrazine with carbonyl groups at 1,3-position of GO yields the pyrazoline moiety at the edge of the exfoliated carbon network. Further, the XPS data of the bombarded N-rGO films at the threshold applied potential of ∼3 keV for 10 min show that the position of the N1s XPS peak shifts from 400.05 to 398.6 eV due to the bombardment, indicating a conversion occurs from non-aromatic pyrazoline to aromatic pyrazole moiety. The electrical results reveal that the conductivity of the N-rGO/pyrazole film (47,600 S/m) is higher than the N-rGO/pyrazoline film (25,000 S/m) by virtue of the enhancement in the length of the conjugation π bond. The conversion of pyrazoline to pyrazole is discussed based on the activation energy.