Photocatalytic activity of MAl2O4 (M = Mg, Sr and Ba) for hydrogen production

Abstract This work reports the hydrogen production of aluminate spinel type materials, MAl 2 O 4 (M = Mg, Sr, and Ba), prepared by solid state method. Characterization was carried out by means of X-ray diffraction (XRD), scanning electronic microscopic (SEM), UV–vis spectroscopy, BET method, chronoamperometry, and EIS. Through electrochemical impedance and UV–vis spectroscopy it was possible the determination of the valence and conduction band edge potential, to define the transfer charge mechanism during the hydrogen production reaction. The photocatalytic measurements coupled with a gas chromatographic system indicated that MgAl 2 O 4 showed the best rate of 7.3 μmol·g −1 ·h −1 for magnesium aluminate, without any co-catalyst or sacrificial reagent. The tendency of the photocatalytic activity for hydrogen production in this work is as follows: MgAl 2 O 4  > BaAl 2 O 4  > SrAl 2 O 4 . When Al 2 O 3 was used as co-catalyst mixed with Magnesium aluminate (MgAl 2 O 4 ), the photoactivity was enhanced, increasing up to 9 times the hydrogen production (64 vs. 7.3 μmol·g −1 ·h −1 ). Additionally, photo-corrosion test indicated that all samples were chemically stable under irradiation conditions.