Photoelectrochemical, photocatalytic and electrochemical hydrogen peroxide production using Fe/S-codoped TiO2 nanotubes as new visible-light-absorbing photocatalysts

Abstract

Codoping of TiO2 nanotube with iron and sulfur considerably improved the photocatalytic and photoelectrocatalytic preparation of hydrogen peroxide using TiO2 in the absence of organics scavengers. One-step anodization of titanium was used to synthesize Fe-doped, S-doped and Fe/S-codoped TiO2 nanotubes. FE-SEM, TEM, XRD, EDX and EDX-Mapping analyses were used to characterize the structure of the nanomaterials prepared. The photoelectrochemical characteristics of the doped and codoped titanium dioxide electrodes were studied under xenon lamp illumination in 0.1 M aqueous solution of potassium hydrogen phthalate. A maximum photocurrent density of 130 µA/cm2 was shown by Fe/S-codoped TiO2 nanotube electrode (sample Fe3S-TNT), which is 13 times greater than that of undoped TiO2 nanotube. H2O2 production remarkably increased by the simultaneous application of the bias potential and light irradiation compared with photocatalytic and electrocatalytic H2O2 preparation. According to the results, more photogenerated electrons are produced with the help of bias potential and the recombination of photogenerated electron–hole pairs is reduced in photoelectrocatalytic (PEC) production of hydrogen peroxide. Therefore, more electrons are available to reduce oxygen and thus more hydrogen peroxide is produced. In this work, a novel method has been developed to improve the photocatalytic activity of TiO2 nanotubes by codoping of iron and sulfur, and new insights into the development of a photoelectrocatalytic system for H2O2 synthesis are provided.