Photoelectrochemical water oxidation of GaP1−xSbx with a direct band gap of 1.65 eV for full spectrum solar energy harvesting

Hydrogen produced using artificial photosynthesis, i.e. solar splitting of water, is a promising energy alternative to fossil fuels. Efficient solar water splitting demands a suitable band gap to absorb near full spectrum solar energy and a photoelectrode that is stable in strongly alkaline or acidi...

Full description

Saved in:
Bibliographic Details
Published in:Sustainable energy & fuels 2019, Vol.3 (7), p.1720-1729
Main Authors: Alqahtani, Mahdi, Sathasivam, Sanjayan, Chen, Lipin, Jurczak, Pamela, Piron, Rozenn, Levallois, Christophe, Létoublon, Antoine, Léger, Yoan, Boyer-Richard, Soline, Bertru, Nicolas, Jean–Marc Jancu, Cornet, Charles, Wu, Jiang, Parkin, Ivan P
Format: Article
Language:English
Subjects:
Alternative energy sources
Aqueous solutions
Current efficiency
Electrolytes
Energy
Energy gap
Energy harvesting
Fossil fuels
Hydrogen
Illumination
Molecular beam epitaxy
Organic chemistry
Oxidation
Photoelectric effect
Photoelectric emission
Photosynthesis
Silicon
Silicon substrates
Solar energy
Splitting
Titanium dioxide
Water splitting
Wavelengths
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Hydrogen produced using artificial photosynthesis, i.e. solar splitting of water, is a promising energy alternative to fossil fuels. Efficient solar water splitting demands a suitable band gap to absorb near full spectrum solar energy and a photoelectrode that is stable in strongly alkaline or acidic electrolytes. In this work, we demonstrate for the first time, a perfectly relaxed GaP0.67Sb0.33 monocrystalline alloy grown on a silicon substrate with a direct band gap of 1.65 eV by molecular beam epitaxy (MBE) without any evidence of chemical disorder. Under one Sun illumination, the GaP0.67Sb0.33 photoanode with a 20 nm TiO2 protective layer and 8 nm Ni co-catalyst layer shows a photocurrent density of 4.82 mA cm−2 at 1.23 V and an onset potential of 0.35 V versus the reversible hydrogen electrode (RHE) in 1.0 M KOH (pH = 14) aqueous solution. The photoanode yields an incident-photon-to-current efficiency (IPCE) of 67.1% over the visible range between wavelengths 400 nm to 650 nm. Moreover, the GaP0.67Sb0.33 photoanode was stable over 5 h without degradation of the photocurrent under strong alkaline conditions under continuous illumination at 1 V versus RHE. Importantly, the direct integration of the 1.65 eV GaP0.67 Sb0.33 on 1.1 eV silicon may pave the way for an ideal tandem photoelectrochemical system with a theoretical solar to hydrogen efficiency of 27%.
ISSN:2398-4902
DOI:10.1039/c9se00113a