Hydrogen Production and Characterization of MLaSrNb₂NiO₉ (M = Na, Cs, H) Based Photocatalysts

Novel photocatalysts MLaSrNb 2 NiO 9 (M = Na, Cs, H) were prepared for H 2 evolution from an aqueous methanol solution under both UV and visible light (>420 nm) irradiation. CsLaSrNb 2 NiO 9 (CNO) with a 2D layered structure (similar to that of CsCa 2 Nb 3 O 10 ) shows a much higher activity than the NaLaSrNb 2 NiO 9 (NNO) photocatalyst that consists of a 3D cubic perovskite crystal structure (ABO 3 ). Experimental results show that Cs ions in CNO can be replaced by protons using a 1.0 M HNO 3 solution, forming a new photocatalyst, HLaSrNb 2 NiO 9 (HNO), whereas Na + in NNO cannot be exchanged by H + under the same conditions. Results show that partially exchanging Cs ions with protons significantly improves the photocatalytic activity of CNO-based photocatalyst. It is found that the higher activities of CNO and HNO compared with that of NNO are attributed to larger surface areas and the 2D layered structure.