title: A Facile Electrochemical Reduction Method for Improving Photocatalytic Performance of α-Fe2O3Photoanode for Solar Water Splitting.
abstract: Electrochemical reduction method is used for the first time to significantly improve the photo-electrochemical performance of α-Fe2O3photoanode prepared on fluorine-doped tin oxide substrates by spin-coating aqueous solution of Fe(NO3)3followed by thermal annealing in air. Photocurrent density of α-Fe2O3thin film photoanode can be enhanced 25 times by partially reducing the oxide film to form more conductive Fe3O4(magnetite). Fe3O4helps facilitate efficient charge transport and collection from the top α-Fe2O3layer upon light absorption and charge separation to yield enhanced photocurrent density. The optimal enhancement can be obtained for <50 nm films because of the short charge transport distance for the α-Fe2O3layer. Thick α-Fe2O3films require more charge and overpotential than thinner films to achieve limited enhancement because of the sluggish charge transport over a longer distance to oxidize water. Electrochemical reduction of α-Fe2O3in unbuffered pH-neutral solution yields much higher but unstable photocurrent enhancement because of the increase in local pH value accompanied by proton reduction at a hematite surface.
authors.forename: Jue
authors.initials: J
authors.lastname: Wang
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Waters
authors.forename: Patrick
authors.initials: P
authors.lastname: Kung
authors.forename: Seongsin M
authors.initials: SM
authors.lastname: Kim
authors.affiliation: Department of Chemistry and Biochemistry, University of Mississippi , Oxford, Mississippi 38655, United States.
authors.forename: John T
authors.initials: JT
authors.lastname: Kelly
authors.affiliation: Department of Chemistry and Biochemistry, University of Mississippi , Oxford, Mississippi 38655, United States.
authors.forename: Louis E
authors.initials: LE
authors.lastname: McNamara
authors.affiliation: Department of Chemistry and Biochemistry, University of Mississippi , Oxford, Mississippi 38655, United States.
authors.forename: Nathan I
authors.identifier: http://orcid.org/0000-0002-6221-2709
authors.initials: NI
authors.lastname: Hammer
authors.affiliation: Department of Chemistry, Tulane University , New Orleans, Louisiana 70118, United States.
authors.forename: Barry C
authors.identifier: http://orcid.org/0000-0002-8611-8186
authors.initials: BC
authors.lastname: Pemberton
authors.affiliation: Department of Chemistry, Tulane University , New Orleans, Louisiana 70118, United States.
authors.forename: Russell H
authors.initials: RH
authors.lastname: Schmehl
authors.forename: Arunava
authors.initials: A
authors.lastname: Gupta
authors.forename: Shanlin
authors.identifier: http://orcid.org/0000-0003-2226-9687
authors.initials: S
authors.lastname: Pan
keywords: electrochemical reduction; hematite; magnetite; solar energy; water splitting