Industries use phenolic compounds (o-nitrophenol) as the intermediates for the preparation of the dyes, making the phenols the common pollutants in industrial waste-water and the environment [1–2]. Phenolic compounds are regarded as priority pollutants and listed as hazardous pollutants by the environmental protection agencies of India [3]. The release of the ortho-nitrophenols into the environment without treatment or partial treatment poses a severe threat to living beings in the ecological system [4]. Even though several methods are available for treating these compounds, like the Fenton process, membrane filtration, electrochemical methods, biodegradation etc., they have high associated costs and require more skills for implementation [5–6]. Thus, there is a need for cost-effective methods, and the photocatalytic method is highly reliable and eco-friendly.
Further, they have excellent stability, affordability, and biocompatibility. Many metal oxide semiconductors have recently been the subject of many photocatalytic studies for removing pollutants [7]. Numerous photocatalysts active in visible light have been studied to oxidize different contaminants [8–10]. Recently used copper oxide nanoparticles [11] to degrade the o-nitrophenol under visible light and achieved degradation removal efficiencies of up to 95.3%. Cu nps for the degradation of the phenol [12] and gained 88% of removal by using an extra LED lamp setup which is not possible for the application in the real-time environment for the degradation. Nickel-doped MOFs for the degradation of the phenolic compounds [13] and achieved a 74% removal; even though this method is efficient and applicable for the degradation of the pollutants only drawback of this method is associated with high costs. Inspired by these publications and to prepare novel new composites for the degradation of the phenolic substance at lower costs, we have selected zirconium dioxide (ZrO2) for this study [14, 15].
Owing to its unique optical and electrical characteristics and with average estimations ranging from 4.0 to 7.0 eV, based on this range of ZrO2, with a band gap relatively less. Furthermore, fabrication procedures are also used because of the synthesized nanomaterials' more excellent crystallinity, controlled morphology, and fine particle size distribution [16, 17]. In recent years, various strategies, like metal doping, metal oxides, and proper backings, such as diminished graphene oxide, were employed to adjust the band gap energy of ZrO2 and advance its apparent light photocatalytic movement [1, 2, 18–20]. The high surface area of reduced graphene oxide (RGO), which is helpful for charge transfer and dissociation, makes it good support. RGO's excellent electron conduction is thought to cause its increased photocatalytic capabilities in RGO/metal oxide NC materials [21, 22]. Thus, in the current study, we report the photocatalytic properties of ZrO2-RGO NC on O-Nitrophenol removal as a typical organic pollutant in the present work. In addition, the work involves the hydrothermal production of ZrO2-RGO NC. The current synthesis method is simple, and the observed results are better than the available literature. According to the findings, ZrO2-RGO NC outperformed ZrO2 nanoparticles in O-Nitrophenol photocatalytic degradation efficiency.