Activation of Ultrathin Films of Hematite for Photoelectrochemical Water Splitting via H2 Treatment. Issue 9 (4th February 2015)

• Record Type: Journal Article
• Authors: Moir, Jonathon; Soheilnia, Navid; Liao, Kristine; O'Brien, Paul; Tian, Yao; Burch, Kenneth S.; Ozin, Geoffrey A.
• Is Part Of: ChemSusChem. Volume 8:Issue 9(2015:May)
• Page Start: 1557
• Page End: 1567
• Publication Date: 2015-02-04
• Subjects: Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201402945
• Languages: English
• ISSNs: 1864-5631

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Thermal treatment of ultrathin films of hematite (α‐Fe₂O₃) under an atmosphere of 5 % H₂ in Ar is presented as a means of activating α‐Fe₂O₃ towards the photoelectrochemical splitting of water. Spin‐coated films annealed in air exhibited no photoactivity, whereas films treated in hydrogen exhibited a photocurrent response. X‐ray photoelectron spectroscopy and UV/Vis absorption spectroscopy results showed that the H₂‐treated films contain oxygen vacancies, which suggests improved charge transport. However, Tafel slopes, scan‐rate dependent measurements, and kinetic analyses performed by using H₂O₂ as a hole scavenger suggested that surface modification may also contribute to their induced photoactivity. Electrochemical impedance spectroscopy results revealed the buildup of a surface trap capacitance at the point of photocurrent onset for the hydrogen‐treated films under illumination. A decrease in charge trapping resistance was also observed, which suggests improved transport of charges away from the surface.</p> </abstract>