title: Electrocatalytic and photocatalytic hydrogen production from acidic and neutral-pH aqueous solutions using iron phosphide nanoparticles.
abstract: Nanostructured transition-metal phosphides have recently emerged as Earth-abundant alternatives to platinum for catalyzing the hydrogen-evolution reaction (HER), which is central to several clean energy technologies because it produces molecular hydrogen through the electrochemical reduction of water. Iron-based catalysts are very attractive targets because iron is the most abundant and least expensive transition metal. We report herein that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions. As an electrocatalyst operating at a current density of -10 mA cm(-2), FeP nanoparticles deposited at a mass loading of ∼1 mg cm(-2) on Ti substrates exhibited overpotentials of -50 mV in 0.50 M H2SO4 and -102 mV in 1.0 M phosphate buffered saline. The FeP nanoparticles supported sustained hydrogen production with essentially quantitative faradaic yields for extended time periods under galvanostatic control. Under UV illumination in both acidic and neutral-pH solutions, FeP nanoparticles deposited on TiO2 produced H2 at rates and amounts that begin to approach those of Pt/TiO2. FeP therefore is a highly Earth-abundant material for efficiently facilitating the HER both electrocatalytically and photocatalytically.
authors.affiliation: Department of Chemistry and Materials Research Institute, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Callejas
authors.forename: Joshua M
authors.initials: JM
authors.lastname: McEnaney
authors.forename: Carlos G
authors.initials: CG
authors.lastname: Read
authors.forename: J Chance
authors.initials: JC
authors.lastname: Crompton
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Biacchi
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Popczun
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Gordon
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Lewis
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Schaak
keywords: electrocatalysis; hydrogen evolution reaction; metal phosphides; nanoparticles; photocatalysis