Direct Water Splitting under Visible Light with Nanostructured Hematite and WO3 Photoanodes and a GaInP2 Photocathode
A p-GaInP{sub 2} photocathode was paired with nanostructured hematite and tungsten trioxide photoanodes to investigate the utility of these systems for direct water splitting under visible light illumination. For the hematite system, under illumination at open-circuit conditions, the potential of hematite shifts cathodically and that of the GaInP{sub 2} shifts anodically. Under short-circuit condition and visible light illumination, the combination of the two photoelectrodes can split water, though with a very low rate of a few {micro}A/cm{sup 2} even at an intensity of 1 W/cm{sup 2}. It was determined that the very low photocurrent from the hematite nanorod photoelectrode limits the short-circuit current of the two-photoelectrode combination. Similar potential shifts were observed with the nanostructured WO{sub 3}/GaInP{sub 2} combination. However, at light intensities below 0.2 W/cm{sup 2}, the short-circuited combination would not split water due to an insufficient potential difference. Above 0.2 W/cm{sup 2}, the combination can split water under visible light, with {approx}20 {micro}A/cm{sup 2} obtained at 1 W/cm{sup 2}. A linear photocurrent-light intensity relationship was observed and was attributed to efficient charge transfer and a low recombination of the charge carriers. The bandgap and the associated absorption limit of WO{sub 3} remain a challenge for a higher efficiency system.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC36-99-GO10337
- OSTI ID:
- 939536
- Journal Information:
- Journal of the Electrochemical Society, Vol. 155, Issue 5, 2008; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
Similar Records
Photoelectrochemical Hydrogen Production
Dye-sensitized nanostructured p-type nickel oxide film as a photocathode for a solar cell