“…the photoreduction of water to hydrogen. [9][10][11] Amongst them, the extensively studied alkali-metal tantalates, i.e., ATaO 3 (A= Na, K) have been shown to exhibit remarkable photocatalytic hydrogen generation activity. ), 5,6 perovskite-type layered oxides (SrTiO 3 , K 4 Nb 6 O 17 , ATaO 3 (A= Na, K)), A 2 La 2 Ti 3 O 10 , (A= Na, K, Rb) 7,8 and tunnel-structured oxides (BaTi 4 O 9 , A 2 Ti 6 O 13 (A= Na, K, Rb), Sr 2 KTa 5 O 15 ).…”