Angstrom Thick ZnO Passivation Layer to Improve the Photoelectrochemical Water Splitting Performance of a TiO₂ Nanowire Photoanode: The Role of Deposition Temperature.

ABSTRACT: In this paper, we demonstrate that angstrom thick single atomic layer deposited (ALD) ZnO passivation can significantly improve the photoelectrochemical (PEC) activity of hydrothermally grown TiO₂ NWs. It is found that this ultrathin ZnO coating can passivate the TiO₂ surface defect states without hampering the carrier's transfer dynamics. Moreover, a substantial improvement can be acquired by changing the deposition temperature of the ZnO layer (80?°C, and 250?°C) and named as 80?°C TiO₂-ZnO, and 250?°C TiO₂-ZnO. It was found that the deposition of this single layer in lower temperatures can lead to higher PEC activity compared to that deposited in higher ones. As a result of our PEC characterizations, it is proved that photoconversion efficiency of bare TiO₂ NWs can be improved by a factor of 1.5 upon coating it with a single ZnO layer at 80?°C. Moreover, considering the fact that this layer is a passivating coating rather than a continuous layer, it also keeps the PEC stability of the design while this feature cannot be obtained in a thick shell layer case. This paper proposes a bottom up approach to control the electron transfer dynamics in a heterojunction design and it can be applied to other metal oxide combinations.

SUBMITTER: Ghobadi A 

PROVIDER: S-EPMC6218493 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature