Synthesis conditions effect on the of photocatalytic properties of MnWO_4 for hydrogen production by water splitting

摘要

This work aims to study the synthesis conditions effect on the photocatalytic properties of manganese tungstate (MnWO4) for H-2 production by the water splitting reaction under visible light irradiation. This is achieved by relating the materials characterization and photocatalytic evaluation of MnWO4 at different synthesis conditions. MnWO4 was synthesized through a precipitation reaction between Mn2+ and (Wo(4))(2-) ionic species, while adding oleic acid (OA) as surfactant at two concentrations (0.1% and 1% V) and using three different stirring methods: magnetic stirring (AM), ultrasound (US) and high-shear stirring (UT). Characterization was carried out by TGA, XRD, BET surface area, UV-Vis spectroscopy and FESEM. XRD patterns confirm the wolframite structure of MnWO4. BET surface area increased by using UT stirring. UV-Vis spectroscopy results revealed indirect transition Eg values of approximate to 2 eV, favorable for the MnWO4 photoactivation under visible light irradiation. During the photocatalytic evaluation, sample 1%-UT produced the highest H-2 amount among all samples with a value of 72 mu molH(2)g(-1), which was far higher compared to WO3, which was taken as a reference photocatalyst. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.