Photoelectrochemical Activity of TiO2/MWCNT Thin-Film Electrodes with Different Film Structures Prepared by Combining Electrophoretic Deposition and Sol–Gel Method

Abstract

Photoelectrodes have attracted significant attention in green hydrogen production via water electrolysis. Among others, titanium oxide (TiO2) is a representative photoelectrode for the conversion of solar energy in the ultravisible region into electrical and chemical energies. However, the poor solar adsorption of this material and the low anode reaction rate have limited the efficiency of hydrogen production via water electrolysis. In addition, there is an urgent need for more ecofriendly hydrogen production systems. The composite films of TiO2 and electronically conductive materials with various structures have been investigated to improve the photoelectrochemical activity of TiO2 by increasing the effective surface area of TiO2 and electronic conductivity of the films, which suppress the electron–hole pair combination. Herein, TiO2 and multiwalled carbon nanotube (MWCNT) composite films with various structures are prepared using the sol–gel method and electrophoretic deposition simultaneously, i.e., sol–gel electrophoretic deposition, under different solution conditions. Scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) results reveals that additives and the mixing ratio of TiO2 sol and MWCNT dispersion solution in the electrophoresis bath affect film structure. Thin-film electrodes with different structures show different photoelectrochemical activities. Most as-fabricated TiO2/MWCNT composite thin-film electrodes outperform pristine TiO2 thin-film electrodes. TiO2 deposition on the MWCNT network surface with an antenna-like shape yields the best photoelectrochemical activity, achieving a low film resistance and ∼80 % anatase/rutile ratio.

Keywords

• sol–gel electrophoretic deposition
• photocatalysis
• hydrogen generation
• nanocarbons