In this work, we report the evaluation of a (CuO/WO₃)-CuWO₄ heterostructured system as a methanol and acetone gas sensor in different configurations, contrasted with the pure oxides CuO and WO₃. The samples were synthesized using a modified precipitation route followed by a single thermal treatment step to induce multiphase simultaneous crystallization. The structural characterization by XRD showed that all the materials presented the formation of monoclinic CuO and WO₃ and triclinic CuWO₄. No additional phases were detected in the samples, and a reduction in the crystallite size of the CuO phase after the crystallization in the heterostructured system was observed. FE-SEM analysis made it possible to directly observe the morphology and the structures of the samples at the nanometer scale, showing a heterogeneous grain formation and supporting the formation of a heterostructure. UV-Vis DRS was used to study the optical properties of the materials, and the presence of two optical band gaps was successfully determined, which provides further evidence of heterostructure formation via this modified synthesis route. The variation in the resistance of the materials was observed in the presence of methanol and acetone vapors, where the heterostructure exhibited a substantial change in performance in the configuration with 40% copper precursor (Cu40:W60), the sample that presented the highest response as a sensor against these VOCs. To our knowledge, this is the first time that this system has been reported as a gas sensor, using the multiple configurations of the (CuO/WO₃)-CuWO₄ heterostructured system.

Here, we present a green coprecipitation synthesis route for silver-functionalized copper and iron oxide nanocomposites (Cu2O/CuO/Fe2O3@Ag) using guava (Psidium guajava) fruit extract as reducing and stabilizing agent. The novelty of this approach lies in the unexplored use of guava, a widely available biomass rich in phytochemicals, to produce multifunctional nanocomposites with enhanced properties. The structural and morphological analyses (XRD, FTIR, SEM, TEM) confirmed the presence of crystalline phases of Fe2O3, Cu2O, CuO, and Ag, along with nanoflake-like and sphericlike morphologies and nanometric particle sizes. Magnetic characterization (VSM) revealed a change from paramagnetic behavior in non-functionalized samples to weak ferromagnetism with reduced coercivity and magnetization upon silver incorporation. The antibacterial assays demonstrated that the functionalized nanocomposites exhibited strong inhibitory effects against the multidrug-resistant pathogen Klebsiella pneumoniae, achieving substantial growth inhibition at 500 ppm. Our findings highlight the potential of guava fruit extract as a sustainable precursor for the biogenic synthesis of silver-functionalized Fe–Cu oxide nanocomposites, offering a promising route for environmentally friendly nanomaterials with applications in biomedical and environmental fields.

La síntesis de materiales es un área científica que se ocupa de diseñar y fabricar materiales con propiedades específicas para diversas aplicaciones. Desde los orígenes de la humanidad, el ser humano ha buscado crear y mejorar objetos, herramientas, instrumentos, industrias, tecnologías, dispositivos, entre otros, para satisfacer sus necesidades. Por lo tanto, el progreso social ha generado una creciente demanda y diversidad de materiales. Es por esto que el estudio de los materiales, tanto el perfeccionamiento de los existentes como el desarrollo de nuevos, es un campo de relevancia e impacto en el ámbito científico global. Considerando estos aspectos, este documento ofrece una reseña de los métodos de síntesis de materiales más destacados, tanto por rutas húmedas como por rutas secas. El objetivo principal es ofrecer al lector una guía con detalles formales, conceptuales y experimentales que le serán de gran utilidad para realizar un proceso de síntesis de un material determinado por estos métodos.