“…Tin(II) niobate (SnNb 2 O 6 ), which possesses the possible band position to allow overall water splitting, can absorb visible light at up to ca. 540 nm (2.3 eV) by contributing to the hybridization between Sn 5s and O 2p orbitals. , Hence, SnNb 2 O 6 has been developed by various methods including solid-state synthesis, , flux-assisted synthesis, − microwave-assisted synthesis, solvothermal synthesis, and hydrothermal synthesis , (the synthesis method, precursors, and band gap energy of SnNb 2 O 6 previously reported and in the present study are summarized in Table S1). It has been reported that SnNb 2 O 6 enables H 2 and O 2 evolutions from aqueous solutions containing sacrificial reagents under visible light irradiation (>420 nm) and that the photocatalytic activity of SnNb 2 O 6 depends on the existence of tetravalent tin (Sn 4+ ) on the surface. , Actually, cobalt oxide (CoO x ) cocatalyst loading suppresses the oxidation of Sn 2+ on the SnNb 2 O 6 surface, and it enables highly efficient O 2 evolution from water .…”