Photocatalytic activity of exfoliated graphite-TiO$_2$ nanocomposites

TL;DR

This study develops a simple, low-cost method to create graphite-TiO2 nanocomposites with enhanced photocatalytic activity, demonstrating improved pollutant degradation and elucidating the underlying charge transfer mechanisms.

Contribution

A novel one-step liquid-phase exfoliation process for graphite-TiO2 nanocomposites that enhances photocatalytic efficiency without complex procedures or surfactants.

Findings

Nanocomposites degrade 40% more pollutants than pure TiO2.

Electron transfer from TiO2 to graphite reduces charge recombination.

Ultrafast spectroscopy reveals rapid charge transfer within picoseconds.

Abstract

We investigate the photocatalytic performance of nanocomposites prepared in a one-step process by liquid-phase exfoliation of graphite in the presence of TiO$_2$ nanoparticles (NPs) at atmospheric pressure and in water, without heating or adding any surfactant, and starting from low-cost commercial reagents. The nanocomposites show enhanced photocatalytic activity, degrading up to 40$\%$ more pollutants with respect to the starting TiO$_2$-NPs. In order to understand the photo-physical mechanisms underlying this enhancement, we investigate the photo-generation of reactive species (trapped holes and electrons) by ultrafast transient absorption spectroscopy. We observe an electron transfer process from TiO$_2$ to the graphite flakes within the first picoseconds of the relaxation dynamics, which causes the decrease of the charge recombination rate, and increases the efficiency of the reactive species photo-production.