Event Title

Sustained Photocurrent in CdS/a-Fe2O3:Co Stacked Thin Films on Titania-Coated Transparent Conductive Substrates

Poster Number

15

Presenter Information

Tyra Douglas, Winthrop University

Faculty Mentor

Clifton Harris, Ph.D.

College

College of Arts and Sciences

Department

Chemistry, Physics and Geology

Location

Richardson Ballroom

Start Date

24-4-2015 1:20 PM

End Date

24-4-2015 2:50 PM

Description

The viability of water-splitting catalysts as commercial sources of renewable energy is strongly dependent on the ability of these materials to utilize the visible portion of the solar spectrum, though most narrow band gap materials (Eg < 3eV) are capable of efficiently driving only one-half of the water-splitting reaction (i.e, the hydrogen-evolution reaction or the oxygen-evolution reaction), not both. In the absence of sacrificial reagents, these materials are subject to deactivation or decomposition. Stacked thin films of CdS (Eg 2.4 eV) and a-Fe2O3 (Eg 2.2 eV) have been fabricated by sequential electrodeposition on titania-coated transparent conductive oxide substrates to photocatalytically drive the full water-splitting reaction. Under visible irradiation, a-Fe2O3 is known to drive the oxygen-evolution reaction, leaving behind an accumulation of conduction band electrons. These electrons act to suppress the decomposition of the hydrogen-evolution catalyst, CdS, which would otherwise proceed due to oxidation of sulfide by trapped valence band holes. However, a-Fe2O3 is a poor conductor. Therefore, the use of dopants, such as Co(II), is necessary to improve electron mobility. Stabilization of the composite is confirmed by a two-electrode photocurrent decay experiment. Further research is underway to optimize the relative film thicknesses.

Comments

Presented at the 249th National Meeting of the American Chemical Society, March 2015

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Apr 24th, 1:20 PM Apr 24th, 2:50 PM

Sustained Photocurrent in CdS/a-Fe2O3:Co Stacked Thin Films on Titania-Coated Transparent Conductive Substrates

Richardson Ballroom

The viability of water-splitting catalysts as commercial sources of renewable energy is strongly dependent on the ability of these materials to utilize the visible portion of the solar spectrum, though most narrow band gap materials (Eg < 3eV) are capable of efficiently driving only one-half of the water-splitting reaction (i.e, the hydrogen-evolution reaction or the oxygen-evolution reaction), not both. In the absence of sacrificial reagents, these materials are subject to deactivation or decomposition. Stacked thin films of CdS (Eg 2.4 eV) and a-Fe2O3 (Eg 2.2 eV) have been fabricated by sequential electrodeposition on titania-coated transparent conductive oxide substrates to photocatalytically drive the full water-splitting reaction. Under visible irradiation, a-Fe2O3 is known to drive the oxygen-evolution reaction, leaving behind an accumulation of conduction band electrons. These electrons act to suppress the decomposition of the hydrogen-evolution catalyst, CdS, which would otherwise proceed due to oxidation of sulfide by trapped valence band holes. However, a-Fe2O3 is a poor conductor. Therefore, the use of dopants, such as Co(II), is necessary to improve electron mobility. Stabilization of the composite is confirmed by a two-electrode photocurrent decay experiment. Further research is underway to optimize the relative film thicknesses.