Facile ion-exchanged synthesis of Sn2+ incorporated potassium titanate nanoribbons and their visible-light-responded photocatalytic activity

Sn2+-incorporated potassium titanate (K2Ti6O13) nanoribbons were prepared by a facile acid-free ion-exchanged method in a dehydrated methanol solution at room temperature. XRD patterns suggested that K2Ti6O13 (KTO) and Sn2+-incorporated KTO (SKTO) are well crystallized with monoclinic phase structures. The mole ratio of incorporated Sn2+ to K+ in SKTO was estimated to be 2. X-ray photoelectron spectrum showed that the Sn species of SKTO consisted of 90% of Sn2+ and 10% of Sn4+, suggesting that part of Sn2+ was oxidized to Sn4+ in the incorporation process. The band gap of SKTO was 0.7 eV narrower than that of KTO, which was derived from lift of the top of the valence band due to the hybridization of Sn5s and O2p orbitals. The SKTO nanoribbons showed remarkable photocatalytic activities for H2 evolution and rhodamine B degradation under visible light irradiation (λ ≥ 420 nm). The photocatalytic mechanism and durability were studied in detail. The advantage of this acid-free ion-exchange method is ease of ion-exchange of K+ with H+ and maintenance of the integrity of the 1D nanoribbon structures. This method can be applied to preparation of other Sn2+-incorporated compounds with special nanostructures.