Synthesis and Photocatalytic Activity of La5Ti2Cu(S1−xSex)5O7 Solid Solutions for H2 Production under Visible Light Irradiation. Issue 6 (30th March 2017) - Nandy, Swarnava
Abstract: The effects of substituting selenide for sulfide ions in La5 Ti2 CuS5 O7 were studied, with the aim of developing visible‐light‐driven photocatalysts with longer absorption edge wavelengths. La5 Ti2 Cu(S1− x Se x )5 O7 (LTCS1− x Se x O) solid solutions were obtained over the composition range of 0≤ x ≤1 by a solid‐state reaction, and their physical properties and photocatalytic activities during the H2 evolution reaction in aqueous solutions were assessed. Structural refinements revealed that the lattice constants and cell volumes of the LTCS1− x Se x O series follow Vegards' law. With increases in the Se 2− content, the LTCS1− x Se x O absorption edge shifts monotonically toward longer wavelengths, to a maximum of 820 nm for LTCSeO ( x= 1). Those materials for which x ≤0.8 generated H2 from aqueous solutions containing Na2 S and Na2 SO3 as electron donors under visible‐light irradiation ( λ >420 nm) after surface modification with in situ precipitated NiS. Comparatively higher H2 evolution was observed for LTCS1− x Se x O with lower Se 2− levels, although the sample for which x= 0.2 generated H2 under visible light at wavelengths longer than 640 nm, whereas the LTCSO did not. Abstract : Moonstone : La5 Ti2 Cu(S1− x Se x )5 O7 (LTCS1− x Se x O) oxysulfoselenide materials, solid solutions of La5 Ti2 CuS5 O7 and La5 Ti2 CuSe5 O7, absorb visible light of longer wavelengths than La5 Ti2 CuS5 O7 (see picture) and show photocatalytic activity in the H2 evolution reaction from aqueous solution containing electron donors.