## 3 Results
### Catalyst Characterization
This carbon matrix not only provides a large surface area and electron-conductive network but also enhances the dispersion of the CuFe nanoparticles [70]. Interestingly, nitrogen was not detected in the EDS analysis, which could be due to the limitations of EDS in detecting low concentrations of light elements. However, XPS analysis confirmed the presence of nitrogen in low amounts, possibly from nitrogen doping or residual biomass nitrogen incorporated during pyrolysis. Although undetectable by EDS, these nitrogen sites may still play an important role in modifying the electronic properties of the carbon matrix, potentially enhancing its binding affinity and catalytic performance. Figure 4: FT-IR spectra acquired from the samples. The magnetization behavior of the samples was examined via hysteresis curves at room temperature, offering valuable insights into their magnetic properties and their implications for catalytic applications (Figure 6). As anticipated, CWM showed no magnetic properties, consistent with its carbonaceous and non-magnetic nature. In contrast, the CuFeNPs sample displayed a classic magnetic hysteresis loop, achieving a saturation magnetization of 31.5 emu g\({}^{-1}\). The presence of this loop indicates ferromagnetic behavior with notable magnetic retention. This ferromagnetism is attributed to the magnetic interactions between Fe and Cu ions within the spinel structure of the nanoparticle [71]. However, this retention can lead to nanoparticle agglomeration, a common drawback for ferromagnetic materials, as the particles retain magnetization even after removing the magnetic field. Such agglomeration can limit particle dispersion, reducing the accessibility of catalytic sites. Upon analyzing the binary composite CuFeNPs@TWM, an increase in magnetization was observed, reaching a saturation value of 40.1 emu g\({}^{-1}\) at 1 T applied field. Interestingly, no remanent magnetization was detected, indicating a shift to superparamagnetic behavior. This transformation suggests that the synthesis conditions of the binary composite, particularly the high-temperature process, altered the magnetic interactions within the material [72]. High-temperature synthesis has been shown to influence crystallinity, particle size, and atomic arrangements, which can enhance magnetization by aligning magnetic domains more effectively without inducing remanence. The superparamagnetic behavior observed in CuFeNPs@TWM, characterized by the S-shaped magnetization curve and zero remanence, is particularly advantageous. Superparamagnetic materials exhibit high magnetic susceptibility, allowing them to become strongly magnetized in the presence of an external magnetic field but immediately return to zero magnetization once the field is  
Figure 5: SEM images for (**a**) TWM, (**b**) CuFeNPs, and (**c**) CuFeNPs@TWM; and (**d**) EDS elemental mapping for (**c**). removed. This is ideal for applications where reversible magnetic manipulation is required, such as catalyst separation in water treatment. The immediate loss of magnetization upon removing the field prevents agglomeration, which improves particle stability and maintains a high surface area accessible for catalytic activity. Additionally, high saturation magnetization enhances the ease of separation, as a modest magnetic field can effectively collect the particles without risking residual magnetization that could lead to re-agglomeration. The textural properties of the catalysts were studied using sorttometry. Nitrogen adsorption/desorption is shown in Figure S5. The analysis showed IV-type isotherm for TWM and CuFeNPs@TWM, associated with mesoporous structures [73; 74], and III-type isotherm for CuFeNPs, which are characteristics of agglomerates of nanoparticles, with low interaction with the adsorbate [75]. In addition, H3-type hysteresis was found for TWM and CuFeNPs@TWM, suggesting slit-like pores, characteristic of graphitic materials.