Photodegradation of phenol using reconstructed Ce doped Zn/Al layered double hydroxides as photocatalysts

• Ce was incorporated to ZnAl LDH by coprecipitation in a single step.
• A distortion of the atomic planes in the direction [1 1 0] is produce by Ce ions.
• XPS study confirms the co-existence of Ce4+ and Ce3+ species.
• Ce4+ acts as a trap of the photogenerated electron, decreasing the recombination.
• The maximum content of Ce for an optimal photocatalytic behavior is 5%.

ZnAlCe layered double hydroxides (LDH) with different content of Ce (3.5, 5.0 and 10.0% mol) were successfully synthesized in one step by the co-precipitation technique. The partial incorporation of cerium into the layers of the material can be appreciated in the XRD diffraction patterns, showing some deformation in the crystallographic direction (1 1 0) of the ZnAlCe LDHs. In the samples calcined at 400 °C, the UV–vis-DRS study showed a shift of the absorption edge toward the blue region of the spectra as a result of the cerium incorporation to the ZnAl LDH; the analysis of XPS confirms the co-existence of Ce4+ and Ce3+ in the ZnAlCe LDHs. The photodegradation and mineralization of phenol under UV irradiation was remarkably improved in the sample containing 5% mol of Ce. A mechanism where cerium in the layered material promotes the separation of the photogenerated electron–hole pairs is proposed. In this mechanism, Ce4+ acts as electron scavenger, facilitating the electron transfer toward adsorbed O2 and an accumulation of holes, increasing the generation of radicals OH.

A distortion of the atomic planes in the direction [1 1 0] appears with the presence of Ce in ZnAlCe LDHs. A proposed mechanism explains the role of Ce4+ in ZnAlCe LDHs, acting as a photogenerated electron (e−) scavenger and producing an accumulation of photogenerated holes (h+), which may help the OH radicals generation.Figure optionsDownload high-quality image (160 K)Download as PowerPoint slide