Issue 123, 2015

Graphene-intercalated Fe2O3/TiO2 heterojunctions for efficient photoelectrolysis of water

Abstract

Interfacial modification of α-Fe2O3/TiO2 multilayer photoanodes by intercalating few-layer graphene (FLG) was found to improve water splitting efficiency due to superior transport properties, when compared to individual iron and titanium oxides and heterojunctions thereof. Both metal oxides and graphene sheets were grown by plasma-enhanced chemical vapor deposition. Compared to the onset potential achieved for α-Fe2O3 films (1 V vs. RHE), the α-Fe2O3/TiO2 bilayer structure yielded a better onset potential (0.3 V vs. RHE). Heterojunctioned bilayers exhibited a higher photocurrent density (0.32 mA cm−2 at 1.23 V vs. RHE) than the single α-Fe2O3 layer (0.22 mA cm−2 at 1.23 V vs. RHE), indicating more efficient light harvesting and higher concentration of photogenerated charge carriers. For more efficient charge transport at the interface, a few layer graphene sheet was intercalated into the α-Fe2O3/TiO2 interface, which substantially increased the photocurrent density to 0.85 mA cm−2 (1.23 V vs. RHE) and shifted the onset potential (0.25 V vs. RHE). Ultrafast transient absorption spectroscopy studies indicated that the incorporation of FLG between the α-Fe2O3 and TiO2 layers resulted in reduced recombination in the α-Fe2O3 layer. The results showed that graphene intercalation improved the charge separation and the photocurrent density of the FTO/α-Fe2O3/FLG/TiO2 system.

Graphical abstract: Graphene-intercalated Fe2O3/TiO2 heterojunctions for efficient photoelectrolysis of water

Supplementary files

Article information

Article type
Paper
Submitted
08 Sep 2015
Accepted
05 Nov 2015
First published
13 Nov 2015

RSC Adv., 2015,5, 101401-101407

Graphene-intercalated Fe2O3/TiO2 heterojunctions for efficient photoelectrolysis of water

A. Kaouk, T.-P. Ruoko, Y. Gönüllü, K. Kaunisto, A. Mettenbörger, E. Gurevich, H. Lemmetyinen, A. Ostendorf and S. Mathur, RSC Adv., 2015, 5, 101401 DOI: 10.1039/C5RA18330H

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