Facile solution synthesis of α-FeF3·3H2O nanowires and their conversion to α-Fe2O3 nanowires for photoelectrochemical application.
We report for the first time the facile solution growth of α-FeF(3)·3H(2)O nanowires (NWs) in large quantity at a low supersaturation level and their scalable conversion to porous semiconducting α-Fe(2)O(3) (hematite) NWs of high aspect ratio via a simple thermal treatment in air. The structural characterization by transmission electron microscopy shows that thin α-FeF(3)·3H(2)O NWs (typically <100 nm in diameter) are converted to single-crystal α-Fe(2)O(3) NWs with internal pores, while thick ones (typically >100 nm in diameter) become polycrystalline porous α-Fe(2)O(3) NWs. We further demonstrated the photoelectrochemical (PEC) application of the nanostructured photoelectrodes prepared from these converted hematite NWs. The optimized photoelectrode with a ~400 nm thick hematite NW film yielded a photocurrent density of 0.54 mA/cm(2) at 1.23 V vs reversible hydrogen electrode potential after modification with cobalt catalyst under standard conditions (AM 1.5 G, 100 mW/cm(2), pH = 13.6, 1 M NaOH). The low cost, large quantity, and high aspect ratio of the converted hematite NWs, together with the resulting simpler photoelectrode preparation, can be of great benefit for hematite-based PEC water splitting. Furthermore, the ease and scalability of the conversion from hydrated fluoride NWs to oxide NWs suggest a potentially versatile and low-cost strategy to make NWs of other useful iron-based compounds that may enable their large-scale renewable energy applications.
Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA.
Linsen
L
Li
Yanghai
Y
Yu
Fei
F
Meng
Yizheng
Y
Tan
Robert J
RJ
Hamers
Song
S
Jin
D004563:Electrochemistry; D005290:Ferric Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D005459:Fluorides / Q000138:chemical synthesis* / Q000737:chemistry; D053770:Nanowires / Q000737:chemistry*; D010316:Particle Size; D010783:Photometry; D016062:Porosity; D012666:Semiconductors; D012996:Solutions; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
D005290:Ferric Compounds; D012996:Solutions; C545851:ferric fluoride; D014867:Water; C000499:ferric oxide; D005459:Fluorides