Oriented titania nanotube biphase junction arrays on water splitting

Abstract

Photocatalyst with phase junction is of great importance to achieve high charge separation and transfer efficiency on solar energy utilization. Herein, an oriented anatase/rutile biphase junction based on TiO2 nanotube arrays are facile prepared by novel oriented thermal annealing method. Its phase distribution and proportion can be tuned by adjusting heat radiation direction and time, respectively. Light absorption spectroscopy and photoelectrochemical measurements reveal that the oriented phase junction is crucial for charge transfer and separation. The sample containing with 34.4% rutile phase has the highest incident photon-to-current efficiency and charge separation efficiency, and achieves ca. 2.2 and 4.7 folds photocurrent density enhancement compared to pristine anatase and rutile phase TiO2 arrays, respectively. The photocurrent density of oriented biphase junction arrays (0.458 mA·cm−2 at 1.23 V vs RHE) is also significantly higher than random phase junction sample or previous reported result. This work demonstrates that the great potential of oriented biphase junction arrays can be applied in efficient charge separation and transfer on solar energy conversion.