# Interfacial Characterization of the Electrochemical Adsorption of Caffeine on Poly(pyrrole) Nanotubes/Silica

## TL;DR

This study explores how caffeine adsorbs onto a modified electrode made of polypyrrole nanotubes and silica, showing improved performance.

## Contribution

The work introduces a novel PPyNT/SiO2 electrode with enhanced caffeine adsorption and surface heterogeneity.

## Key findings

- PPyNT/SiO2 electrode showed a 2-fold increase in maximum caffeine adsorption capacity.
- The electrode surface was more heterogeneous compared to pristine PPyNTs.
- Silica's adsorption capability was enhanced by the less oxidized form of PPyNTs.

## Abstract

In this work, a polypyrrole
nanotube/silica (PPyNT/SiO2)-modified electrode was prepared
by an all-electrochemical
route
and characterized by electrochemical, spectroscopic, and microscopy
analyses; scanning electron microscopy confirmed the superimposition
of a particulate silica on the PPyNTs without any loss of electroactivity
of conducting polypyrrole. The PPyNTs/SiO2 electrode was
employed for the electroadsorption of caffeine, where it was found
that in its less oxidized form, the PPyNTs boosted the adsorption
capability of intrinsic silica. Electrochemical impedance spectroscopy
(EIS) modeling was employed and modeled with equivalent circuit methodology,
and all the results were compared with the Sips isotherm model, showing
that the PPyNTs/SiO2 electrode presented a more heterogeneous
surface (n
S = 1.25) and a nearly 2-fold
increase in maximum adsorption capacity (q
ms) compared to pristine PPyNTs.