The embedding of metal oxide nanoparticles into polymeric matrices creates composite materials with interesting physicochemical properties and potential applications in various fields, such as environmental and food monitoring, optical devices, and biosensors.

In the present paper, In₂O₃-based composites were prepared by an ex situ method, where In₂O₃ nanostructures were dispersed into a nafion matrix through an ultrasound mixing process under rigorous control of the process parameters (time, temperature, ultrasound intensity, frequency, etc). The morphological and structural behaviors of the composites were evaluated using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), and the surface-wetting capacity was determined by contact angle (CA) measurements. Morphological analysis showed that the In₂O₃ nanoparticles were uniformly distributed in the nafion matrix, with a slight tendency to agglomerate. The structural investigation revealed a slight shift in the characteristic In₂O₃ peaks, indicating a good interaction between the main phase characteristics of the composite. Nafion exhibits high hydrophobicity properties, and by adding In₂O₃ to the matrix, a decrease in the contact angle at approximately 91° was observed while maintaining hydrophobicity. The electrochemical performance of the composites was evaluated by cyclic voltammetry. This study provides new insights into composite materials and highlights their performance in the development of biosensors, focusing on the properties of composite films.

Acknowledgments: This work was supported by the Core Program within the National Research Development and Innovation Plan 2022-2027, carried out with the support of MCID, project no. 2307 (µNanoEl).