Metal-free surface modification strategy to enhance photoelectrocatalytic activity of TiO2 nanomeshes for water remediation

Abstract

To further improve the photoelectrocatalytic activity of TiO2 through metal-free strategy for wastewater treatment, a new type of graphite carbon/TiO2 heterojunction nanomeshes (GC/TiO2 HNMs) was successfully prepared by the facile electrochemical-hydrothermal method. By optimizing the precursor (glucose) concentration and reaction current, the GC/TiO2 HNMs shows excellent photoelectrocatalytic activity towards methylene blue, rhodamine B, methyl orange and methyl violet, which could degrade the dyes by more than 95% within 120 min. The degradation efficiency of the GC/TiO2 HNMs did not decrease significantly after being reused for 5 times. Besides, modification of graphite carbon on TiO2 NMs could increase the photocurrent by more than 5 times and dramatically decrease the ionic resistance. The recombination of photogenerated electron-hole pairs was prevented and the electrons were quickly conducted by graphite carbon, which facilitates the production of •O2- and enhances the photoelectrocatalytic activity of the GC/TiO2 HNMs. Free radical quenching experiments and electron paramagnetic resonance spectroscopy (EPR) verified that •O2- played the main role in photoelectrocatalytic dye degradation.