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

Novel photocatalysts MLaSrNb2NiO9 (M = Na, Cs, H) were prepared for H-2 evolution from an aqueous methanol solution under both UV and visible light (> 420 nm) irradiation. CsLaSrNb2NiO9 (CNO) with a 2D layered structure (similar to that of CsCa2Nb3O10) shows a much higher activity than the NaLaSrNb2NiO9 (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 HNO3 solution, forming a new photocatalyst, HLaSrNb2NiO9 (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.