# Tea (Camellia sinensis) Extract-Mediated Green Synthesis of Co3O4 and Co3O4@Graphene Nanocomposites for Multifunctional Applications in Pollutant Degradation, Sensing, and Energy Storage

## TL;DR

Researchers developed a green method to create Co3O4 and graphene nanocomposites using tea extract, which can be used to break down pollutants, detect chemicals, and store energy.

## Contribution

A novel green synthesis method using tea extract to create Co3O4@Graphene nanocomposites with multifunctional applications.

## Key findings

- Co3O4@Graphene nanocomposites showed 80% catalytic efficiency in degrading methylene blue dye.
- The nanocomposites had a detection limit of 0.01–224 μM for low-DPA with high sensitivity.
- The material exhibited a maximum specific capacitance of 349 F/g at 5 mV/s scan rate for energy storage.

## Abstract

A novel solution-mixing
method was proposed to synthesize Co3O4/graphene
nanocomposites (Co3O4@Gr) using a green tea
leaf (Camellia sinensis) extract as
the reducing agent. XRD analysis shows that the as-prepared
Co3O4@Gr exhibits a cubic spinel crystal structure.
From morphological analysis, the obtained Co3O4 NS forms spherical clusters that are uniformly distributed on the
graphene surface. FT-IR and Raman analyses confirmed the strong molecular
and vibrational interactions between the Co3O4 NS and Gr. The suppressed PL intensity peak of the Co3O4@Gr NCs indicated significant inhibition in the recombination
of charge carriers between the hybrid orbitals within the composites.
As a result, the catalytic efficiency of Co3O4@Gr NCs increased to 80% compared to pristine Co3O4, which exhibited only 45% efficiency against methylene blue
(MB) dye. Moreover, the as-prepared NCs exhibited a detection limit
of 0.01–224 μM, demonstrating a superior low-DPA detection
with high sensitivity. The Co3O4@Gr/GCE exhibits
admirable selectivity for various pesticides, fungicides, and metal
ions, with outstanding reproducibility and stability. From electrochemical
investigations, the highest specific capacitance values of the as-synthesized
Co3O4@Gr were 349 F/g at a scan rate of 5 mV/s
and 158 F/g at a current density of 1 A/g.