Abstract
The electronic structure, in particular the band edge position, of photocatalyst in presence of water is critical for photocatalytic water splitting. We propose a direct and systematic density functional theory (DFT) scheme to quantitatively predict band edge shifts and their microscopic origins for aqueous 2D photocatalyst, where thousands of atoms or more are able to be involved. This scheme is indispensable to correctly calculate the electronic structure of 2D photocatalyst in the presence of water, which is demonstrated in aqueous MoS2, GaS, InSe, GaSe and InS. It is found that the band edge of 2D photocatalysts are not rigidly shifted due to water as reported in previous studies of aqueous systems. Specifically, the CBM shift is quantitatively explained by geometric deformation, water dipole and charge redistribution effect while the fourth effect, i.e., interfacial chemical contact, is revealed in the VBM shift. Moreover, the revealed upshift of CBM in aqueous MoS2 should thermodynamically help carriers to participate in hydrogen evolution reaction (HER), which underpin the reported experimental findings that MoS2 is an efficient HER photocatalyst. Our work paves the way to design 2D materials in general as low-cost and high-efficiency photocatalysts.
Highlights
Generating hydrogen by photocatalytic water splitting through photoelectrochemical cells (PECs), as first demonstrated in the pioneer work by Fujishima and Honda[1], is a promising approach for producing environmentally friendly and scalable solar fuel
Material/water system self-consistently, it is able to capture the correct band edge shifts and the complete microscopic origins of these shifts for cases when conduction band minimum (CBM) and valence band maximum (VBM) are shifted by different values due to the presence of water, e.g., MoS2/water, GaS/water, GaSe/water, InSe/water, and InS/water systems
The findings of the band edge shifts is of great importance for artificial photosynthesis, e.g., MoS2 is good for hydrogen evolution reaction (HER) but not oxygen evolution reaction (OER)
Summary
Generating hydrogen by photocatalytic water splitting through photoelectrochemical cells (PECs), as first demonstrated in the pioneer work by Fujishima and Honda[1], is a promising approach for producing environmentally friendly and scalable solar fuel. To determine band edge positions of 2D materials in the presence of water and answer the above issues, as well as to design 2D photocatalysts in general, direct DFT calculations to determine the band edge shifts of the combined 2D-photcatlysts/ water system are indispensable. To achieve this goal, it is necessary to solve large number of atoms in the combined system. With respect to the third effect, the charge our direct DFT approach (shown in Fig. 1) to analyze the band redistribution brought by the interfacial interaction between 2D
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
