## 3 Results and Discussion
### Structural and Morphological Analysis
[21] demonstrated that variations in synthesis methods directly affect the atomic arrangement within these clusters, altering the density and nature of the defect states. These structural modifications, in turn, impact charge separation efficiency and recombination dynamics, ultimately influencing the photocatalytic performance. Therefore, synthesis-dependent differences in the crystalline and local structures modulate the electronic landscape of FeWO\({}_{4}\). A more disordered arrangement may promote shallow-level recombination paths (as indicated by the PL peak at 441 nm), while simultaneously reducing the density of deep traps and enhancing the charge carrier mobility. The schematic in the inset of Figure 2D illustrates this mechanism, showing electrons excited to the CB and recombining through defect states located near the CB rather than deeply trapped ones--leading to relatively faster but less detrimental recombination. Together, the PL and UV-vis results demonstrate that iron oxides are promising materials for photocatalytic applications. Moreover, their optical properties can be effectively tailored through controlled synthesis routes, enabling direct and efficient optimization of their photocatalytic performance. To investigate the morphology and surface texture of the iron oxides, FE-SEM analysis was performed, and the results are shown in Figure 3. The Fe\({}_{2}\)(MoO\({}_{4}\))\({}_{3}\) crystals exhibited an elongated morphology with well-defined exposed surfaces. Based on the Wulff construction, this morphology is likely dominated by the (001) and (110) surfaces. The main morphological differences observed between the samples highlight the greater number of exposed faces and surfaces in Fe\({}_{2}\)(MoO\({}_{4}\))\({}_{3}\), which may enhance the adsorption capacity and promote the formation of vacancies--features supported by the PL results. In a study by [PERSON] et al. [14], Fe\({}_{2}\)(MoO\({}_{4}\))\({}_{3}\) synthesized via a conventional 24 h hydrothermal route exhibited an aggregated morphology and a band gap of 2.66 eV. In contrast, the present synthesis produced a more well-defined crystalline structure with a narrower band gap of 2.06 eV. This suggests that enhanced crystal growth along specific (001) and (110) surfaces may contribute to improved photocatalytic performance by facilitating charge transport and increasing the density of active surface sites in Fe\({}_{2}\)(MoO\({}_{4}\))\({}_{3}\). On the other hand, the FeWO\({}_{4}\) crystals exhibit a noticeably different morphology. The FE-SEM images reveal a highly porous and fluffy texture with irregularly shaped particles. These smaller particles suggest a larger specific surface area compared to Fe\({}_{2}\)(MoO\({}_{4}\))\({}_{3}\). The synthesis of FeWO\({}_{4}\) with tailored morphologies, such as hierarchical plates, nanorods, and complex microstructures, has recently attracted significant attention due to its impact on catalytic performance. In our study, the combination of a co-precipitation route with microwave-assisted hydrothermal treatment resulted in an aggregated morphology composed of ultrafine crystallites. This approach not only promotes particle size control, but also enables crystal formation within a significantly shorter synthesis time, representing a promising strategy for scalable production. [PERSON] et al. (2019) reported that FeWO\({}_{4}\) microcrystals synthesized by means of a similar method exhibited significant photocatalytic activity for RhB degradation under visible light. Likewise, [PERSON] et al. (2019) synthesized FeWO\({}_{4}\) nanorods via a hydrothermal route using a precursor complex, achieving a narrow band gap of 1.98 eV. Their findings demonstrated that reducing crystal size can enhance photocatalytic performance compared to bulk or larger particles. These results support the promising photocatalytic potential of the FeWO\({}_{4}\) synthesized in this study. Figure 3: FE-SEM images of (**A**) Fe\({}_{2}\)(MoO\({}_{4}\))\({}_{3}\) and (**B**) FeWO\({}_{4}\) samples.