Facile Solution Synthesis of a-FeF3-H2O Nanowires and Their Conversion to a-Fe2O3 Nanowires for Photoelectrochemical Application
|Title||Facile Solution Synthesis of a-FeF3-H2O Nanowires and Their Conversion to a-Fe2O3 Nanowires for Photoelectrochemical Application|
|Publication Type||Journal Article|
|Year of Publication||2012|
|Authors||Li, L, Yu, Y, Meng, F, Tan, Y, Hamers, RJ, Jin, S|
We report for the first time the facile solution growth of α-FeF3·3H2O nanowires (NWs) in large quantity at a low supersaturation level and their scalable conversion to porous semiconducting α-Fe2O3 (hematite) NWs of high aspect-ratio via a simple thermal treatment in air. The structural characterization by transmission electron microscopy shows that thin α-FeF3·3H2O NWs (typically <100 nm in diameter) are converted to single-crystal α-Fe2O3 NWs with internal pores, while thick ones (typically >100 nm in diameter) become polycrystalline porous α-Fe2O3 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/cm2 at 1.23 V vs. reversible hydrogen electrode potential after modification with cobalt catalyst under standard conditions (AM 1.5 G, 100 mW/cm2, pH = 13.6, 1M 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.