Layered Dion-Jacobson type niobium oxides for photocatalytic hydrogen production prepared via molten salt synthesis

Abstract

A class of Dion-Jacobson type layered perovskite niobium oxides (AB2Nb3O10 with A=K, Rb, Cs and B=Ca, Sr, Ba) was prepared via molten salt method for the first time. By dissolving oxide and carbonate precursors in A-cation chloride melts, this type of synthesis needs only two hours of preparation time resulting in highly crystalline layered niobates at a much shorter synthesis time compared to conventional syntheses, like the solid state reaction. Beside detailed materials characterization, we investigated the influence of A-cation and B-cation variation on the band gap and photocatalytic activity for hydrogen production. It was found that the band gap decreases with the increase in size of the B-cation. A strong dependence on interlayer spacing (influenced by the size of the A-cation) and lattice relaxation can be derived from the steady-state hydrogen evolution rates.