Iron oxides and hydroxides (Fe-OH) extracted from natural sources have garnered significant attention for their diverse catalytic applications. This article provides a comprehensive overview of the catalytic potential of naturally occurring Fe-OH, focusing on the influence of natural sources and preparation methods on their morphological characteristics and application in heterogeneous catalysis. The unique physicochemical properties of these catalysts, including their high surface area, redox activity, and tunable surface chemistry, make them promising candidates for various catalytic processes. The review discusses key catalytic reactions facilitated by natural Fe-OH, such as advanced oxidation processes (AOPs), electrochemical applications, catalytic cracking, and biodiesel production. Furthermore, it highlights recent advancements and challenges in utilizing these materials as heterogeneous catalysts. By presenting an analysis of the catalytic potential of natural iron oxides, this review aims to stimulate further research about the use of these materials, which are widely distributed in the Earth’s crust.

Fe ₃ O ₄ /N-MWCNT enhances electron transfer through metal–carbon interactions, improving ORR activity and enabling efficient electro-Fenton degradation of methyl orange.

Currently, wound dressing technology is of significant interest in order to avoid undesired effects when burns or skin wounds are treated, especially their risk for microbial contamination and subsequent infection. Silver nanoparticles (AgNPs) have claimed importance as antimicrobial agents. For these reasons, a comparative study of different methods to synthesize electrospun polymeric fibers loaded with AgNPs (Ag⁺/PCLPVP) such as direct blending, ultraviolet irradiation, thermal treatment, and silver mirror reaction methods were done. The morphology and size of the fibers were investigated using the SEM, where the loading of the AgNPs in the fibers was measured with EDS analysis. FTIR, Raman spectroscopy, XRD, and TGA analysis were applied to measure the physicochemical properties of the fibers. DLS study allowed us to measure the size and surface charge of the obtained materials. The antimicrobial efficiency was carried out against Staphylococcus aureus and Escherichia coli bacteria for 24 h. Cytotoxicity was evaluated with the MTT assay using HFF1 cells. The results showed that the method with the best antimicrobial effect in both bacteria is the UV irradiation conducted before the electrospinning process. The UV radiation method also promotes good distribution efficiency, the physicochemical properties obtained were desirable for wound dressings, and the particle size within nanoparticle interval (~17 nm). Therefore, the most promising method for the preparation of Ag+/PCLPVPbased wound dressings was UV irradiation.

The limited mechanical properties of composite materials, including stiffness, strength, and biocompatibility, restrict their effectiveness in biomedical applications. This research enhanced the mechanical properties and biocompatibility of polylactic acid and carbon fiber-reinforced composites (PLA/CFRCs) by incorporating multi-walled carbon nanotube (MWCNT) fillers. The methodology involved synthesizing MWCNTs and integrating them into PLA/CFRC laminates using fusion-blending, dispersion, and interlaminar spray-coating. Raman spectroscopy confirmed the presence of MWCNTs, with characteristic D and G band peaks and an I_D/I_G of 1.44 ± 0.089. SEM revealed MWCNTs in the PLA/CFRC matrix and allowed size determination, with an outer diameter range of 125–150 nm and a length of 14,407 ± 2869 nm. FTIR identified interactions between the matrix and the MWCNTs, evidenced by band shifts. TGA/DSC analysis showed thermal stability above 338 °C for all composites. The tensile tests revealed that all composites had values greater than 19 GPa for the elastic modulus and 232 MPa for the ultimate strength. Cytotoxicity assays confirmed biocompatibility, and all samples maintained a cell growth rate greater than 80%. This study highlighted the potential of nanotechnology to optimize the mechanical behavior of polymer-based composites, expanding their applicability in biomedical fields.