Facile synthesis of SrTiO3/CoAlMnO4 nanocomposite: A rechargeable heterojunction photocatalyst with superior hydrogen storage capability

Herein, SrTiO3/CoAlMnO4 nanocomposite was synthesized by a facile method. It should be acknowledged that CoAlMnO4 was synthesized for the first time. After optimizing the synthesis conditions, the photocatalytic activities of CoAlMnO4 (SC I), SrTiO3 (SC II), and the nanocomposite were studied. The nanocomposite represented the highest efficiency under both UV and visible. Scavenger experiment results showed that the photocatalytic mechanism of this nanocomposite follows the type-I heterojunction configuration. Hence, the high efficiency of nanocomposite under UV irradiation can be justified by decreasing the band gap, because of the transition of the photo-generated electrons from CBSCII with more negative potential to CBSCI and movement of the holes from VBSCII with more positive potential to VBSCI, according to the related mechanism for this configuration. This configuration under visible irradiation isn't acceptable because SC II is a UV-active semiconductor, but the better performance of SrTiO3/CoAlMnO4 under vis irradiation can be related to defects existing on interfacial of two semiconductors which can trap charge carriers. The electrochemical properties of SC I as a new perovskite were studied. The better property of CoAlMnO4 than CoMn2O4 was due to substitution of Al+3 with Mn+3 which decreases enthalpy of formation of oxygen vacancies and facilitates formation of active sites.