Favourable band edge alignment and increased visible light absorption in β-MoO3/α-MoO3 oxide heterojunction for enhanced photoelectrochemical performance
Journal article, 2018

Optimum band gap values, favourable band edge positions and stability in the electrolyte are critical parameters required for a semiconductor to have efficient photoelectrode properties. The present investigation carried out on the phase pure α & β MoO3 thin film shows that the low bandgap β-MoO3 possesses a mis-alignment with the water oxidation potential, while a more suitable band alignment is observed for the comparatively large bandgap α-MoO3. Both experimental and DFT calculations show that the valence edge of the orthorhombic (α-MoO3) phase is located at a higher energy (0.9 eV higher in VB-XPS and 1 eV higher in the DOS plots) than the monoclinic (β-MoO3) phase, while the conduction edge value is roughly at the same energy level (−2.5 eV) in both polymorphs. Based on the above investigations, an all oxide heterojunction comprising of β-MoO3/α-MoO3 is found to be suitable for improved PEC performance due to favourable energy band diagram and increased visible light absorption in β-MoO3. Significantly higher cathodic photocurrent is observed for the β-MoO3/α-MoO3 (1.6 mA/cm2 at applied bias of −0.3VRHE under simulated 1 sun irradiation) as compared to the very low anodic response in β-MoO3 (∼1.0 nA/cm2) and α-MoO3 (32 μA/cm2).

Oxygen partial pressure

MoO3-polymorphs

DFT Calulations

Solar hydrogen

Oxygen evolution reaction (OER)

Photoelectrochemical (PEC) cell

Author

Nisha Kodan

Indian Institute of Technology Kharagpur

Aadesh P. Singh

Chalmers, Physics, Chemical Physics

Matthias Vandichel

Chalmers, Physics, Chemical Physics

Björn Wickman

Chalmers, Physics, Chemical Physics

Bodh R. Mehta

Indian Institute of Technology Kharagpur

International Journal of Hydrogen Energy

0360-3199 (ISSN)

Vol. 43 33 15773-15783

Driving Forces

Sustainable development

Areas of Advance

Nanoscience and Nanotechnology (SO 2010-2017, EI 2018-)

Energy

Materials Science

Subject Categories

Physical Chemistry

Other Physics Topics

Condensed Matter Physics

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

Chalmers Materials Analysis Laboratory

Nanofabrication Laboratory

DOI

10.1016/j.ijhydene.2018.06.138

More information

Latest update

3/26/2021