A tracer study of a radical produced by UV irradiation on BaTi4O9 photocatalyst surface

A tracer study was performed to assign a radical produced with UV irradiation on photocatalytically active BaTi 4 O 9 for water decomposition. BaTi 4 O 9 was reduced in H 2 and oxidized in 16 O 2 , 17 O 2 or 18 O 2 at different temperatures. The behavior of oxygen exchange was investigated by thermal gravimetric analysis and Raman spectroscopy. Electron magnetic resonance spectra showed that new signals with g ⊥ =2.038 and g ⊥ =2.026 due to hyperfine splitting of 17 O − with A ⊥ =19.1 G appeared when oxidized in 17 O 2 , in addition to normal signals with g ⊥ =2.018 and g ‖ =2.004. The radical is assigned to O − produced from surface lattice oxygen of BaTi 4 O 9 .