Synthesis, characterization and photocatalytic activity of mixed oxides derived from ZnAlTi ternary layered double hydroxides

• Synthesis and characterizations of a new series of ZnAlTi ternary layered double hydroxides.
• Calcination of LDH precursors led to formation of mixed oxides with reduced band gap energies than those of ZnO or TiO2-P25.
• The derived mixed oxides are effective photocatalysts under visible light for dyes degradation.
• Easy separation and possibility of reuse of used catalyst.

A new series of Ti4+ containing ZnAl-LDHs with varying Zn:Al:Ti (~3:1:0–3:0.5:0.5) ratio were prepared by coprecipitation of homogeneous solution metal salts and characterized by various physicochemical methods. Powder XRD revealed the formation of well crystallized LDH even at the highest Ti4+ content. On thermal treatment at 450 °C, the well crystallized LDH precursors yielded mixed oxides with BET surface area in the range 92–118 m2/g. UV–vis diffuse reflection spectroscopy (DRS) showed a marginal decrease of band gap energy for calcined ZnAlTi-LDHs in comparison to either ZnO or TiO2-P25. The TEM analyses of a representative sample (as-synthesized and calcined) indicated more or less uniform distribution of titanium species. The derived mixed oxides from titanium containing LDH precursors demonstrated better activity toward photodegradation of methylene blue and rhodamine B than those of a physical mixture of ZnO and TiO2. Moreover, the present work not only provided a first hand understanding about semiconductor properties of ZnAlTi-LDHs but also demonstrated their potential as photocatalysts for degradation of organic pollutants.

TEM image (dark field) of as-synthesized LDH precursor (ZAT-2).Figure optionsDownload as PowerPoint slide