Preparation and photocatalytic H2-production on α-Fe2O3 prepared by sol-gel. (8th February 2018)

• Record Type: Journal Article
• Authors: Boumaza, S.; Kabir, H.; Gharbi, I.; Belhadi, A.; Trari, M.
• Is Part Of: International journal of hydrogen energy. Volume 43:Number 6(2018)
• Page Start: 3424
• Page End: 3430
• Publication Date: 2018-02-08
• Subjects: Hematite α-Fe2O3 -- Sol-gel -- Photocatalysis -- Hydrogen -- Visible light; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2017.07.227
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: In this work, the hematite α-Fe2 O3 was synthesized by sol-gel method and characterized by X-ray diffraction and optical properties. The XRD patterns realized at different temperatures, show that pure hematite is obtained above 500 °C. The diffuse reflectance gives respectively direct and indirect optical transitions at 2.17 and 2.04 eV, in agreement with the red color. The capacitance measurement of α-Fe2 O3 indicates p type behavior with a conduction band (−1.14 V vs. SCE), more cathodic than the H2 evolution (∼−0.8 V vs. SCE). The oxide was successfully tested for the hydrogen production under visible irradiation (29 mW cm −2 ). α-Fe2 O3 is photo-electrochemically stable in alkaline medium by hole consumption reactions involving X 2− (= SO3 2− and S2 O3 2− ) as hole scavengers. The best photocatalytic activity for H2 production was obtained on α-Fe2 O3, calcined at 500 °C, in (Na2 S2 O3 0.025 M, pH ∼ 13), with an average evolution rate of 0.015 cm 3 h −1 (mg catalyst) −1 and a quantum efficiency of 0.26%. The system shows a tendency toward saturation, due to the competitive reduction of end products with the water reduction and the cathodic shift of the H2 potential. Highlights: The work deals with the hydrogen photo-production on α-Fe2 O3 elaborated by sol-gel under visible irradiation. Pure hematite α-Fe2 O3 is obtained beyond 500 °C with a particle size ∼27 nm. The optical transitions (2.04 and 2.2 eV) make α-Fe2 O3 attractive for the light energy conversion. The capacitance indicates p type conduction with a conduction band more cathodic than that of hydrogen evolution.