## 3 Results and Discussion  
### Characterization of Catalysts  
The co-precipitation method involves mixing solutions of metal salts at specific concentrations in predetermined proportions. A base solution, typically sodium hydroxide (NaOH), is gradually added dropwise to the combined salt solution to adjust its pH. After an aging process with continuous stirring, the resulting product is filtered, cleaned, and dried. During aging, Fe(OH)\({}_{3}\) and Co(OH)\({}_{2}\) formed in the solution are incorporated into the layered double hydroxide (LDH) structure, which can be chemically expressed as [M\({}_{1-x}\)\({}^{2+}\)M\({}_{x}\)\({}^{3+}\)(OH)\({}_{2}\)(A\({}_{n}\)\({}^{-}\))\({}_{x}\)/n]x\({}^{+}\)-mH\({}_{2}\)O [24]. In this expression, M\({}^{2+}\) and M\({}^{3+}\) represent Co\({}^{2+}\) and Fe\({}^{3+}\), respectively, while the interlayer anion A\({}_{n}\)\({}^{-}\) is CO\({}_{3}\)\({}^{2-}\) in this work. Figure 1a presents the X-ray diffraction (XRD) patterns of FeCo-LDHs with Fe\({}^{3+}\)/Co\({}^{2+}\) molar ratios of 1:1, 1:2, and 1:3. According to previous reports [25], typical LDHs exhibit a strong absorption peak at low angles and two weaker, equally spaced peaks at intermediate angles, along with two relatively weak peaks near 60\({}^{\circ}\). The characteristic peaks of LDH (JCPDS 50-0235) are observed at 11.75\({}^{\circ}\), 23.57\({}^{\circ}\), 34.11\({}^{\circ}\), 38.76\({}^{\circ}\), 46.28\({}^{\circ}\), and 60.70\({}^{\circ}\), indicating that LDHs with a high Fe/Co ratio exhibit better crystalline structures. However, for a Fe\({}^{3+}\)/Co\({}^{2+}\) ratio of 1:1, the characteristic peaks were significantly weakened or absent, suggesting that excessively higher Fe\({}^{3+}\)/Co\({}^{2+}\) ratios are unfavorable for forming well-defined LDH structures. Fourier-transform infrared (FTIR) spectroscopy was conducted to identify the functional groups, chemical bonding states, and interlayer anions present in the LDHs. Samples were dried and measured in powder form. Figure 1b shows the FTIR spectra of Fe-Co (1:1), Fe-Co (1:2), and Fe-Co (1:3) samples, which exhibit similar curves. An intensive band between 3427 and 3503 cm\({}^{-1}\) correspond to the stretching vibrations of hydroxyl groups within hydroxylingesite-like layers [26]. The strong peak at 1634 cm\({}^{-1}\) is attributed to the deformation mode of interlayer water molecules, confirming the presence of hydroxyl groups and water in the samples [27; 28]. Various interlayer anions are characteristic of LDHs, and their host-guest affinities follow the order: CO\({}_{3}\)\({}^{2-}\)\(>\) SO\({}_{4}\)\({}^{2-}\)\(>\) OH\({}^{-}\)\(>\) F\({}^{-}\)\(>\) Cl\({}^{-}\)\(>\) Br\({}^{-}\)\(>\) NO\({}_{3}\)\({}^{-}\)\(>\) I\({}^{-}\)[29]. The absorption peak at 1356 cm\({}^{-1}\) corresponds to the vibrational absorption of interlayer CO\({}_{3}\)\({}^{2-}\)[30], suggests that CO\({}_{3}\)\({}^{2-}\) is one of the LDH interlayer anions. Additionally, spectral bands in the range of 1000-400 cm\({}^{-1}\) are associated with metal-oxygen (M-O) or metal-hydroxyl (M-OH) vibrations [31]. Peaks at 732 cm\({}^{-1}\) correspond to Co-OH mode [32]. As shown in Figure 2, the morphological characteristics of Fe-Co (1:3) samples were systematically investigated by transmission electron microscopy (TEM). Layered double hydroxides (LDHs) typically exhibit octahedral symmetry, where the metal cations are located at the centers of the octahedral units and the hydroxide anions occupy the vertices. These structural units are interconnected by edge sharing to form extended two-dimensional coordination layers, resulting in the characteristic lamellar structure of LDHs [33; 34]. TEM images (Figure 2a,b) clearly show the presence of lamellar, layered morphology [34]. In addition to this, a less organized structure is shown, with the lamellae being partially fragmented and irregular.