Strong interfacial charge transfer between hausmannite manganese oxide and alumina for efficient photocatalysis

Well crystalline manganese oxide (Mn3O4) nanoparticles anchored on gamma alumina (c-Al2O3) have been successfully tailored via a proficient and cost effective chemical process as an efficient material for photo catalysis. XRD indicated the composite formation of c-Al2O3 and hausmannite structure of Mn3O4. SEM and TEM revealed that hetero structure of Mn3O4/c-Al2O3 exhibits an amalgam of aggre-gated nanoparticles and nanorods. XPS demonstrated the chemical states of binary nanocomposite. The band gap tuning has been performed with c-Al2O3 nanoparticles by assimilating hausmannite Mn3O4 particles into flower like microstructure of Al2O3. The photoluminescence spectra affirmed the enhancement in charge separation in Mn3O4/c-Al2O3 binary hybrid photocatalyst. The band gap becomes narrow with the increase in concentrations of Mn3O4. The narrowing of band gap is concorded with crys-talline domains of primary aggregated particles. To elucidate the mechanism of the photocatalytic activ-ity linear sweep voltammetry was performed. The results showed that Mn3O4/c-Al2O3 nanocomposite revealed the enhancement in current density as compared to pure c-Al2O3 which confirmed the electron transfer from Mn3O4 to c-Al2O3 through the interfacial potential gradient in conduction bands. The opti-mum concentration of 6.0％Mn3O4/c-Al2O3 for hybrid structure showed an excellent photocatalytic activ-ity under visible light due to narrow band gap energy. High degree distribution of Mn3O4 nano architects overlying on c-Al2O3 induces a significant synergic effect between c-Al2O3 and hausmannite phase of manganese oxide (Mn3O4). This strong interfacial contact between c-Al2O3 and Mn3O4 endures the quick transfer of photo generated charge carriers across interface.