## 1 Introduction  
The presence of contaminants of emerging concern (CECs) in aquatic environments has become a critical concern in recent decades due to their persistence and potential harm to human health and ecosystems [1]. These contaminants include pharmaceuticals,personal care products, endocrine-disrupting chemicals, and industrial compounds that are not completely removed by conventional water treatment processes. As these pollutants accumulate in water bodies, their adverse effects on aquatic life, biodiversity, and public health have sparked an urgent need for more effective water treatment technologies. One of the most promising technologies for addressing this issue is the electro-Fenton (EF) process, a type of advanced oxidation process (AOP). In the EF process, the hydrogen peroxide (H\({}_{2}\)O\({}_{2}\)) is generated electrochemically at the cathode (Equation (1)), which reacts with ferrous ions (Fe\({}^{2+}\)) in the solution, serving as the catalyst to produce hydroxyl radicals (\({}^{\bullet}\)OH) (Equation (2)) [2]. These radicals are highly reactive and degrade a wide range of organic pollutants, including contaminants of emerging concern (Equation (3)) [3]. \[\mathrm{O}_{2}+2\mathrm{H}^{+}+2\mathrm{e}^{-}\rightarrow\mathrm{H}_{2}\mathrm{O }_{2} \tag{1}\]  
\[\mathrm{Fe}^{2+}+\mathrm{H}_{2}\mathrm{O}_{2}\rightarrow{{}^{\bullet}}\mathrm{ OH}+\mathrm{Fe}^{3+}+\mathrm{OH}^{-} \tag{2}\]  
\[\mathrm{CECs}+{{}^{\bullet}}\mathrm{OH}\rightarrow\mathrm{By\text{-products}}+{{}^{ \bullet}}\mathrm{OH}\rightarrow\mathrm{CO}_{2}+\mathrm{ions}+\mathrm{H}_{2} \mathrm{O} \tag{3}\]  
Despite its effectiveness, the high cost of traditional catalysts and the need for sustainable resource management have prompted researchers to explore innovative approaches for making the EF process more sustainable and economically viable. The efficiency of the EF process can be significantly enhanced by using suitable catalysts that promote the generation of hydroxyl radicals [4]. Metal oxides and nanoparticles, such as iron and copper-based catalysts, have been extensively studied for this purpose. When solid catalysts are used, the Fenton reaction primarily occurs on the catalyst's surface, and the surface-based reactions can be summarized by the reactions outlined in Equations (4)-(7). In particular, copper-iron (FeCu) nanoparticles have gained attention due to their magnetic properties, high surface area, and catalytic activity [5; 6; 7]. These nanoparticles can be easily separated and reused, making them an attractive choice for sustainable water treatment. In addition, the presence of copper in FeCu nanoparticles further enhances the electron transfer processes, aiding the Fenton-like reactions (Equations (8) and (9)) and eases the recovery of Fe\({}^{2+}\) (Equation (10)), boosting the overall catalytic activity and efficiency of the reaction [8; 9]. \[\mathrm{\Xi Fe^{2+}+H_{2}O_{2}\rightarrow\mathrm{\Xi Fe^{3+}+{}^{\bullet}} \mathrm{OH}+\mathrm{OH}^{-}} \tag{4}\]  
\[\mathrm{\Xi Fe^{3+}+H_{2}O_{2}\rightarrow\mathrm{\Xi Fe^{2+}+HO_{2}{}^{ \bullet}}+H^{+}} \tag{5}\]  
\[\mathrm{\[PERSON]^{3+}+HO_{2}{}^{\bullet}}\rightarrow\mathrm{\[PERSON]^{2+}+O_{2} +H^{+}} \tag{6}\]  
\[\mathrm{\[PERSON]^{+}+H_{2}O_{2}\rightarrow\mathrm{\[PERSON]^{2+}+{}^{\bullet}} \mathrm{OH}+\mathrm{OH}^{-}} \tag{7}\]  
\[\mathrm{\[PERSON]^{2+}+H_{2}O_{2}\rightarrow\mathrm{\[PERSON]^{+}+HO_{2}{}^{ \bullet}}+H^{+}} \tag{8}\]  
\[\mathrm{\[PERSON]^{2+}+HO_{2}{}^{\bullet}}\rightarrow\mathrm{\Xi Cu^{+}+O_{2} +H^{+}} \tag{9}\]  
\[\mathrm{\[PERSON] Cu^{+}+\mathrm{\[PERSON] Fe^{3+}\rightarrow\mathrm{\[PERSON] Cu^{2+}+\mathrm{ \[PERSON] Fe^{2+}}}}} \tag{10}\]  
However, the practical use of iron-based nanoparticles is often limited by challenges such as nanoparticle aggregation and rapid oxidation [10]. To enhance their stability and performance, various support materials like activated carbon, biochar, zeolites, silica, and clays have been explored [11; 12; 13; 14].