Boosted charge transfer from single crystalline titanium nanotubes for a dual-purpose PEC system

Photoelectrocatalytic (PEC) technology has promising applications. It is capable of effectively generating hydrogen and removing organic pollutant in water at the same time. Though TiO2 materials have been proven an excellent candidate for fabricating PEC electrodes for its low toxicity, high oxidation potential and photocatalytic activity, the catalytic performance of TiO2 electrodes is limited by their low electrons transporting efficiency. In this study, using a facile electrochemical method, we produced single crystalline TiO2 nanotubes (s-TNTs) exposing (001) facets with enhanced charge transfer efficiency than that of common TiO2 nanotubes electrodes (m-TNTs). In this system, the electrochromic s-TNTs electrodes exhibit better performance in generating hydrogen and higher degradation rate of atrazine on s-TNTs than that on common TiO2 nanotubes electrodes (m-TNTs) in varying conditions: electrochemical (EC), photocatalytic (PC), and PEC. Using s-TNTs and s-TNTs@Pd nanocomposites as both photoanode and cathode, the photon-to-current conversion efficiency was significantly enhanced, and the promoted hydrogen production rose obviously. The enhanced charge transfer efficiency of s-TNTs might induce a highly enhancement in the whole PEC system, which could be primarily attributed to the single-crystalline structure and exposed {001} facet. This study could provide new possibility of utilizing single crystalline TiO2 nanotubes for efficient dual-purpose PEC system for its high activity, great stability, low cost and no toxicity. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.