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Synthesis and Photocatalytic Properties of Single Crystalline (Ga1-xZnx)(N1-xOx) Nanotubes |
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| Authors: | Christopher Hahn Melissa A. Fardy Catherine Nguyen Michelle Natera-Comte Sean C. Andrews Peidong Yang |
| Affiliation: | 1. Department of Chemistry, University of California, Berkeley, California 94720 phone:+510 643 1545 fax:+510 642 7301 Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 These authors contributed equally to this work.;2. Department of Chemistry, University of California, Berkeley, California 94720 phone:+510 643 1545 fax:+510 642 7301;3. Department of Chemistry, University of California, Berkeley, California 94720 phone:+510 643 1545 fax:+510 642 7301 Technische Physik, University of Würzburg, Am Hubland, 97074 4. Würzburg, Germany;5. Department of Chemistry, University of California, Berkeley, California 94720 phone:+510 643 1545 fax:+510 642 7301 Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 |
| Abstract: | Recently, (Ga1-xZnx)(N1-xOx) has gained widespread attention as a comparatively high efficiency photocatalyst for visible-light-driven overall water splitting. Despite significant gains in efficiency over the past several years, a majority of the photogenerated carriers recombine within bulk powders. To improve the photocatalytic activity, we used an epitaxial casting method to synthesize single-crystalline, high surface area (Ga1-xZnx)(N1-xOx) nanotubes with ZnO compositions up to x=0.10. Individual nanotubes showed improved homogeneity over powder samples due to a well defined epitaxial interface for ZnO diffusion into GaN. Absorption measurements showed that the ZnO incorporation shifts the absorption into the visible region with a tail out to 500 nm. Gas chromatography (GC) was used to compare the solar water splitting activity of (Ga1-xZnx)(N1-xOx) nanotubes (x=0.05–0.10) with similar composition powders. Cocatalyst decorated samples were dispersed in aqueous solutions of CH3OH and AgO2CCH3 to monitor the H+ reduction and H2O oxidation half reactions, respectively. The nanotubes were found to have approximately 1.5–2 times higher photocatalytic activity than similar composition powders for the rate limiting H+ reduction half reaction. These results demonstrate that improvements in homogeneity and surface area using the nanotube geometry can enhance the photocatalytic activity of GaN:ZnO for solar water splitting. |
| Keywords: | alloy nanotube oxynitride photocatalyst water splitting |