Tuning band alignment and optical properties of 2D van der Waals heterostructure via ferroelectric polarization switchin
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Front. Phys. 15(6), 63504 (2020)
Research article Tuning band alignment and optical properties of 2D van der Waals heterostructure via ferroelectric polarization switching Dimuthu Wijethunge1,2 , Lei Zhang1,2 , Cheng Tang1,2 , Aijun Du1,2,† 1
School of Chemistry and Physics, Queensland University of Technology, Gardens Point Campus, Brisbane, QLD 4000, Australia 2 Centre for Materials Science, Queensland University of Technology, Gardens Point Campus, Brisbane, QLD 4000, Australia Corresponding author. E-mail: † [email protected] Received June 30, 2020; accepted July 28, 2020
Favourable band alignment and excellent visible light response are vital for photochemical water splitting. In this work, we have theoretically investigated how ferroelectric polarization and its reversibility in direction can be utilized to modulate the band alignment and optical absorption properties. For this objective, 2D van der Waals heterostructures (HTSs) are constructed by interfacing monolayer MoS2 with ferroelectric In2 Se3 . We find the switch of polarization direction has dramatically changed the band alignment, thus facilitating different type of reactions. In In2 Se3 /MoS2 /In2 Se3 heterostructures, one polarization direction supports hydrogen evolution reaction and another polarization direction can favour oxygen evolution reaction. These can be used to create tuneable photocatalyst materials where water reduction reactions can be selectively controlled by polarization switching. The modulation of band alignment is attributed to the shift of reaction potential caused by spontaneous polarization. Additionally, the formed type-II van der Waals HTSs also significantly improve charge separation and enhance the optical absorption in the visible and infrared regions. Our results pave a way in the design of van der Waals HTSs for water splitting using ferroelectric materials. Keywords photocatalyst, ferroelectric, MoS2 , In2 Se3 , heterostructures, water splitting, 2D materials
1 Introduction In the context of searching sustainable, economical, and efficient energy generation processes, nature provides perfect insight on what future energy generation should be like. In photosynthesis process, solar energy is converted into chemical energy by plants and such type of conversion can be achieved also through photocatalyst materials, even though the efficiency is far below the natural photosynthesis process. Photocatalyst material has gained immense popularity in research community since the first discovery of ZnO in 1911 [1]. Later, another popular photocatalyst, TiO2 , was reported in 1938, through production of active oxides by absorbing UV on the surface [2]. After several decades Fujishima et al. introduced electrochemical photolysis of water using TiO2 and Pt electrodes [3]. Since then water splitting through solar irradiation into hydrogen and oxygen identified as the efficient reaction for solar chemical energy conversion. Later various photocatalyst such as CeO2 [4], BiVO4 [5], ∗ Special
Topic: Heterojunction and Its Applic
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