## 1 Introduction  
Accumulate persistent organic pollutants (POPs) in the food chain adversely affect human health and the environment. Industrial chemicals (e.g., textile dyes), pesticides, solvents, and pharmaceuticals (such as tetracycline) are the different types of POPs [1, 2]. A prominent POP in this group is tetracycline, which is used extensively as an antibiotic in veterinary medicine and aquaculture [3, 4]. Therefore, it is essential to find practical solutions to remove such POPs from the environmental [5, 6]. Photocatalysis has gained recognition as an environmentally friendly technology at ambient temperature for efficiently mineralizing POPs [7, 8, 9]. This study uses methylene blue and tetracycline as a model of organic pollutants. It endangers aquatic biodiversity when used as a dye or a decontamination, besides removing organic pollutants from organic solutions and releasing toxic compounds due to chemical and biological reaction processes [10; 11]. When irradiated using an appropriate catalyst, methylene blue has been noted as photobleached, photodegraded, and demethylated [12; 13]. With its ability to decimate toxic environmental contaminants, photocatalysis has been given considerable attention. In ecological and biomedical applications, semiconducting metal oxide heterogeneous photocatalysts are exclusively used [14; 15; 16; 17]. Owing to their similar bandgap, TiO\({}_{2}\) and ZnO semiconductors have been widely studied as effective photocatalysts for the photodegradation of organic pollutants [18; 19; 20]. MB also causes the depletion of the dissolved oxygen in water bodies. Different procedures have evolved over the years to enhance the photocatalytic performance of the semiconductor photocatalysts, such as noble metal loading and semiconductor composites and textural design [21]. The specific property of hollow nanostructures of the TiO\({}_{2}\) nanocrystals with internal pores is instrumental for their augmented photocatalytic activity compared to TiO\({}_{2}\) solid nanocrystals [22]. The higher charge carrier mobility of the anatase phase TiO\({}_{2}\) enables it to exhibit higher photocatalytic activity than the rutile phase [23; 24]. [PERSON] et al. demonstrated that noble metals, such as Cu, Au, and Ag, could increase the efficiency of photocatalysis [25]. Of late, graphene has emerged to hold a pivotal position in the environment and in energy [26; 27]. Graphene, with the structure of a two-dimensional macromolecular sheet of carbon atoms, is an excellent electrical conductor with unique mechanical properties and has proved to be an efficient electron-transport material for photocatalytic processes, and it is better than the graphite-like Carbon, C60, polyaniline [28; 29; 30]. Graphene, due to its high surface area and excellent electrical and mechanical properties, is much sought after as a novel substrate for creating hybrid nanostructures in a combination of a variety of nanomaterials by incorporating graphene with metals, metal oxides, and polymers; new applications have been developed in recent times [31; 32; 33; 34]. In the degradation of rhodamine B, the graphene/TiO\({}_{2}\) nanocrystal hybrid material exhibits excellent photocatalytic activity, unlike the other forms of TiO\({}_{2}\)[35]. The enhanced photocatalytic activity is more shown in the catalytic degradation of MB under UV light irradiation by the P25-graphene photocatalyst than by the bare P25 [36]. Similarly, rather than the pure SnO\({}_{2}\) nanoparticles, graphene-embedded SnO\({}_{2}\) nanoparticles exhibited an improved photocatalytic degradation activity with the MB under sunlight [37]. The graphene sheets/ZnO nanocomposites, which show photocatalytic activity, are eminently suitable for various applications in environmental protection [38]. The distinct physical and chemical properties of hafnium oxide (HfO\({}_{2}\)) have made it considerably investigated as an essential dielectric material for a wide range of applications such as dosimeters, biosensors, radiosensitizers, and biomaterials [39; 40; 41; 42].