Yang Yang

Oxide Materials and Devices

Nanjing Tech University, 211816, Nanjing, China

Email: yangy@njtech.edu.cn

Abstract for Presentation

Improving Photoelectrochemical Performance of TiO2 Nanowire Arrays by Designing Specific Core–Shell Interf

Hydrogen generation by water splitting is one possible energy storage solution that enables deeper integration of renewable resources[1-2].Rutile titania (TiO2) has a wide band gap of 3.0 eV and a considerably positive valence band position vs. NHE. In view of water oxidation as the bottleneck step in water splitting, an adequate overpotential obtained by ultraviolet (UV) irradiation on TiO2 provides the possibility to drive water oxidation in a wide pH range. Direct growth of oriented rutile TiO2 single-crystal nanowire arrays could be readily achieved on transparent conductive FTO glass substrates by low-temperature hydrothermal reactions. This synthetic process facilitates the fabrication of photoanodes derived from TiO2 nanowire arrays for photoelectrochemical (PEC) generation of solar hydrogen. Coupling functional thin layers with TiO2 nanowires is an efficient approach to tuning the photoelectric properties of both the parties. In this report, we demonstrate efficient processes for improving PEC performance of TiO2 nanowire arrays by designing specific core–shell interface. Firstly a carbon dots-embedded ZnO amorphous shell is constructed on TiO2 nanowires by a one-step hydrothermal method (Figure 1). Secondly a TiO2 shell that is rich in oxygen vacancy is formed on TiO2 nanowires by thermal treatment of magnetron sputtered Ti thin film. Thirdly a core–shell heterostructure with TiO2 nanowire as core and the MOF NTU-9 as shell is synthesized via a surfactant-free solution approach. By implementation of the above samples as photoanodes for PEC water splitting under full spectrum light illumination, significantly enhanced photocurrent density and hydrogen production efficiency is achieved in each case. We explicate the the specific mechanism for spacial separation of photogenerated electron–hole pairs in TiO2 nanowires and propose how the core–shell interface informs the performance of TiO2-based composites for PEC application.

References 
[1] T. Hisatomi, J. Kubota, K. Domen, Chem. Soc. Rev., 43 (2014) 7520–7535.

[2] H. Song, S. Luo, H. Huang, B. Deng, J. Ye, ACS Energy Lett., 7 (2022 ) 1043–1065