The role of trap-centres on $SrTiO_3$ fine particles during water photolysis

$SrTiO_3$ fine powders prepared by different routes vary considerably by way of type and concentration of defect centres, as revealed by EPR investigations. The predominant electron-centres are $Ti^{3+}-V_O$ and $V^1\hspace{1mm} _{Sr}$, whereas the hole-centres correspond to O− adjacent to strontium vacancies. $SrTiO_3$ particles suspended in dilute acids under low intensity illumination show the presence of OH.s radicals. During water photolysis under band gap irradiation, the hole-centres on $SrTiO_3$ participate in the charge transfer to $OH^−$or other hole-scavenging species such as EDTA, $H_2PO_2^− $ or TEOA. Details of $H_2$ evolution kinetics of sacrificial photolysis system involving $H_2PO_2^−$ and $Pt/SrTiO_3 $ are given. Reactivity of hole-centres on $SrTiO_3$ is higher than those on $TiO_2$, which accounts for $O_2$ evolution in photocatalyzed water-splitting in the case of $SrTiO_3$