Modification of graphene-based nanomaterials with gamma irradiation as an eco-friendly approach for diverse applications: A review

Graphene-based nanomaterials (GBNMs) are versatile due to their large surface area, great mechanical, chemical strength, and excellent electrical properties. The versatility of graphene has increased its applicability therefore several synthesis methods to produce high quality graphene simpler, faster, and cost-effectively are actively explored. The conventional synthesis methods however employ toxic chemicals, high temperatures, and lengthy synthesis times. On the other hand, the gamma (γ) irradiation approach is facile, occurs under ambient conditions and produces graphene composites of high purity. Noteworthy, this technique enables the user to control the synthesis time and total dose, hence minimising the aggregation of the nanomaterial, the main drawback hindering the commercial production of GBNMs. γ-radiolysis synthesized GBNMs exhibit superior optical and electrical properties and hence improved supercapacitance, catalytic, and sensing abilities. Although other reviews addressed the γ-ray synthesis of metallic nanomaterials, polymers, as well as usage of a variety of radiation techniques to fabricate graphene composites, this review focuses solely on the synthesis and modifications of GBNMs via the γ-synthesis technique. Properties of graphene and conventional methods used to reduce graphene oxide (GO) to graphene as well as their shortcomings are highlighted. This is followed by detailing the γ-radiation synthesis technique, its advantages over the conventional methods and the principles thereof. Effects of γ-irradiation and the conditions required for the structural modification of graphene to obtain different graphene composites are detailed. The influence of operational parameters on the fabricated graphene-based composites are discussed followed by summaries of recent developments in the applicability of γ-irradiated GBNMs in catalysis, energy, sensing, and biomedical fields. In addition, this paper presents insights into the challenges posed and provides future research directions and prospects in the field of γ-irradiated GBNMs.