Novel TiO2/Bi4Ti3O12 nanorod arrays decorated with Co-Pi for boosted solar photoelectrochemical water splitting

Abstract

We present a simple methodology to construct novel Co-Pi decorated TiO 2 /Bi 4 Ti 3 O 12 nanorod (TiO 2 /BTO@Co-Pi NR) arrays as photoanode for enhanced water splitting. By using successive ionic layer adsorption and reaction (SILAR) method, controllable amounts of BiOI nanoplates were uniformly immobilized on the hydrothermal grown TiO 2 NR arrays on Fluorine-doped tin oxide (FTO) substrate. TiO 2 /BTO NR heterojunction was conveniently obtained by partial conversion of TiO 2 to high crystallized Bi 4 Ti 3 O 12 through a solid-state reaction with BiOI nanoplates at high temperature. Afterwards, Co-Pi nanoparticles were deposited on TiO 2 /BTO by photoelectrical deposition to generate TiO 2 /BTO@Co-Pi composites. Photoelectrochemical (PEC) measurements have demonstrated that the prepared TiO 2 /BTO photoanode exhibits extremely enhanced performance than pristine TiO 2 for PEC water splitting thanks to the increased visible light absorption and photogenerated charge separation efficiency. Moreover, both the photocurrent density and incident photo-to-current conversion efficiency (IPCE) were further improved after the decoration of Co-Pi. This work provides a feasible and low-cost strategy to establish TiO 2 /Bi 4 Ti 3 O 12 based photoelectrode, therefore, is suitable for practical applications. • Novel TiO 2 /Bi 4 Ti 3 O 12 nanorod arrays were easily constructed by simple SILAR and solid-state reaction. • Controllable Bi 4 Ti 3 O 12 could be formed by adjusting the SILAR cycles to achieve a optimium photocurrent. • BTO can largely enhance the IPCE and photocurrent density, which were further improved by Co-Pi nanoparticles.