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

We present a simple methodology to construct novel Co-Pi decorated TiO2/Bi4Ti3O12 nanorod (TiO2/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 TiO2 NR arrays on Fluorine-doped tin oxide (FTO) substrate. TiO2/BTO NR heterojunction was conveniently obtained by partial conversion of TiO2 to high crystallized Bi4Ti3O12 through a solid-state reaction with BiOI nanoplates at high temperature. Afterwards, Co-Pi nanoparticles were deposited on TiO2/BTO by photoelectrical deposition to generate TiO2/BTO@Co-Pi composites. Photoelectrochemical (PEC) measurements have demonstrated that the prepared TiO2/BTO photoanode exhibits extremely enhanced performance than pristine TiO2 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 TiO2/Bi4Ti3O12 based photoelectrode, therefore, is suitable for practical applications.