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Issue 44, 2011
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Solution-based fabrication of ZnO/ZnSe heterostructure nanowire arrays for solar energy conversion

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Abstract

We report a method for synthesizing ZnO/ZnSe heterostructure nanowire arrays for use in photoelectrochemical (PEC) water splitting. The surfaces of ZnO nanowires immobilized on a conducting glass substrate were modified to form ZnO/ZnSe heterostructure nanowire arrays through a reaction with an aqueous sodium selenite and hydrazine solution. ZnO/ZnSe heterostructure nanowires with different morphologies were synthesized by varying solution concentrations and reaction times. The ZnO nanowire/ZnSe nanoparticle heterostructures (ZS1) were synthesized by a dissolution–recrystallization mechanism. At longer reaction times and higher solution concentrations, the nanostructure arrays transformed into ZnO nanowire/ZnSe nanosphere heterostructure arrays (ZS2) via Ostwald ripening. ZnO/ZnSe heterostructure arrays (ZS1 and ZS2) yielded higher photocurrents than the pristine ZnO nanowire arrays in a PEC water splitting test under AM 1.5G simulated solar light. The ZnO/ZnSe heterostructure array photoanodes exhibited absorption in the visible spectrum (<550 nm in wavelength) with a high incident-photon-to-current-conversion efficiency (IPCE) of up to 47% (ZS1) or 57% (ZS2) at 0.0 V vs. Ag/AgCl. The photoanode yielded a relatively high photocurrent density of 1.67 mA cm−2 (ZS1) or 2.35 mA cm−2 (ZS2) at 0.3 V compared to the ZnO nanowire arrays (0.125 mA cm−2). Structural differences between ZS1 and ZS2 yielded different PEC performances. A comparison to ZS2 revealed that ZS1 exhibited a higher photocurrent density under a low applied potential (from −0.78 V to −0.07 V) and a lower photocurrent density under a high applied potential (above −0.07 V).

Graphical abstract: Solution-based fabrication of ZnO/ZnSe heterostructure nanowire arrays for solar energy conversion

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Publication details

The article was received on 17 Aug 2011, accepted on 12 Sep 2011 and first published on 12 Oct 2011


Article type: Paper
DOI: 10.1039/C1JM14014K
Citation: J. Mater. Chem., 2011,21, 17816-17822
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    Solution-based fabrication of ZnO/ZnSe heterostructure nanowire arrays for solar energy conversion

    S. Cho, J. Jang, S. Lim, H. J. Kang, S. Rhee, J. S. Lee and K. Lee, J. Mater. Chem., 2011, 21, 17816
    DOI: 10.1039/C1JM14014K

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