# Flexible TEMPO-cellulose/silver selenide nanocomposites with advanced optical, electrical, and antimicrobial performance

## TL;DR

Researchers created flexible nanocomposites using cellulose and silver selenide, which show improved optical, electrical, and antimicrobial properties.

## Contribution

The study introduces a novel method to embed silver selenide nanoparticles within cellulose nanofibers for multifunctional applications.

## Key findings

- The nanocomposites showed a significant drop in optical band gap from 4.46 eV to 2.65 eV.
- Conductivity increased by three orders of magnitude in the CNF/Ag2Se I composite compared to pure CNF.
- The material exhibited high antimicrobial activity against E. coli, S. typhimurium, and C. albicans.

## Abstract

Transforming dielectric polymers into conductive or semiconductive materials opens new avenues for advanced and unprecedented applications. Herein, flexible films were fabricated from TEMPO-oxidized cellulose nanofibers/silver selenide (T-CNF/Ag2Se) nanocomposites. Ag2Se particles were in situ prepared in the presence of TEMPO-oxidized cellulose nanofibers to limit the Ag2Se formation within the nanopores of the TEMPO-oxidized cellulose nanofibers. XRD and FTIR patterns verified the effective embedding of Ag2Se nanoparticles within the T-CNF matrix, where Ag2Se crystallized exclusively in the orthorhombic β-Ag2Se phase. For optoelectronic applications, the optical features were investigated, and Ag2Se has a great impact on transmittance, reflectance, optical band gap, and Urbach energy of CNF. The transmittance was reduced from 10% to 2% in the visible region, while the optical band gap dropped from 4.46 eV for CNF to 2.65 eV for CNF/Ag2Se I. Compared with pure CNF, the CNF/Ag2Se I nanocomposites showed broader M″ peaks that shifted towards higher frequencies, indicating enhanced charge-carrier dynamics due to the additional conductive pathways introduced by the Ag2Se nanoparticles. At 313 K, conductivity followed the order of CNF < CNF/Ag2Se III < CNF/Ag2Se < CNF/Ag2Se II < CNF/Ag2Se I, with the conductivity increased by three orders of magnitude for CNF/Ag2Se I compared with that for the pure CNF. The antimicrobial performance of CNF/Ag2Se at different concentrations was evaluated, and it exhibited high toxicity against E. coli, S. typhimurium, and C. albicans, while S. mutans exhibited more resistance against the nanocomposite materials.

Ag2Se was in situ prepared in TEMPO-oxidized cellulose nanofibers for optical , electrical and antimicrobial applications.