Tailored ozone activation on geometrical-site-dependent cobalt with selective coordination

Abstract

Abstract Cobalt-containing spinel oxides are promising platforms to fine-tune the intrinsic activity/selectivity of their geometric sites in catalysis. However, the role of tetrahedrally occupied Co2+ (Co2+ Td) and Co3+ in an octahedral site (Co3+ Oh) in controlling the catalytic activity remains controversial. Herein, we investigated a geometrical-site-dependent catalytic activation of ozone respectively on the Co2+ Td and Co3+ Oh sites. The same exposure of [111] crystal facet is achieved by substituting those undesired sites with catalytically inactive cations. The highly spin-polarized Co2+ Td sites invoke strong orbital interactions and intensive electron transfer with the adsorbed O3 and become the active sites for selectively producing surface-bound hydroxyl radicals (•OH) and avoiding the formation of unfavorable singlet oxygen (1O2), resulting in a 17.6-fold increase in turnover frequency (TOF). This work enlightens the spin-polarized electronic states into regulating the reaction thermodynamics in transition metal oxide-induced catalysis and envisages the practical application potentials of geometric site engineered spinel oxides.