## 1 Introduction  
Recent innovations and technological developments have given rise to interest in advanced oxidation processes (AOPs), which are an effective application in solving serious water pollution problems. Among the many AOPs, the photo-Fenton process has become an attractive alternative method for removing pollutants from water bodies due to its environmental friendliness, suitable price, and wide range of applications [1]. Similarly, semiconducting materials have been used in electro-photocatalysis technology, and have attracted extensive attention due to their low price and lack of secondary pollution. A typical semiconductor catalyst material, TiO\({}_{2}\), has been widely studied due to its high efficiency, non-toxicity, and low cost. However, the wide band gap (3.2 eV) of TiO\({}_{2}\) limits its utilization of visible light. Thus, a semiconductor material with high visible-light utilization is an important parameter. The ternary oxyhalide semiconductor BiOBr is a new type of photocatalyst with a lower bandgap (2.7 eV), high stability, and special layered structure, and is widely used in sensors, catalysts, and optics. In a single tetragonal BiOBr cell, layered [Bi\({}_{2}\)O\({}_{2}\)] and bromine atoms are alternately arranged [2]. Surface chemical materials with a unique mechanism of contaminant removal have been explored as an alternative. Grafting magnetic nanoparticles onto amino functional groups yields amino-functionalized magnetic nanoparticles. The material shows more efficient performance than bare magnetic nanoparticles in water treatment applications. Their magnetic nature is crucial for cost-effective and greener pollutant removal from water, since they are magnetically separated and can be reused without a major change in structure and efficiency [3]. However, the development of Fenton mimicking heterogeneous processes still dominates interest in environmental remediation research. Ferrocene is a highly stable, non-toxic, organometallic compound with high catalytic potential due to its electron donor-acceptor conjugated structure, which serves as a redox switch. The technology uses a supported ionic liquid phase (SILP) catalyst that involves the grafting of ionic liquid-like units onto a porous material with a high surface area. A highly striking strategy is offered by these advanced materials to overcome the impact of ionic liquids, and it opens up a new perspective for powerful green tools and recognizes the goal of sustainable chemical processes [4]. Among the other attempts to improve the performance of the photocatalyst are doping with anionic/cationic species, which has been widely explored [5]. There are two prevailing (complementary) schools of thought on how to improve the use of semiconducting materials as photocatalysts: (i) harvesting visible light, and (ii) decreasing the rate at which the generated hole (h\({}^{+}\)) and electrons (e\({}^{-}\)) recombine [6]. Carbon materials can potentially satisfy both requirements. Carbon materials such as carbon spheres [7], carbon fibers, carbon nanotubes [8], and activated carbon [9] are attractive as an additive to semiconducting metal oxides that form photocatalytic nanocomposites [10]. Carbon-rich materials are typically synthesized by methods that include chemical vapor deposition [11], hydrothermal carbonization [12], and arc discharge [13]. However, the use of such methods requires sophisticated instruments that have a high energy consumption. An alternative simple method to make carbons is via flame pyrolysis, in which waste materials such as waste cooking oil can be used as a carbon source to produce onion-like nanocarbons (OLNCs) [14]. OLNCs are related to the family of carbon fullerenes [15]. They have a graphitic core, abundant surface functional groups, moderate porosity, and can have an inner cavity [16]. In this study, OLNCs were added to TiO\({}_{2}\) to form nanocomposites (TiO\({}_{2}\)/OLNC) for use in the photodegradation of a model complex: methyl orange (MO). [PERSON] et al.