Hydrothermal Synthesis and Visible-Light-Driven Photocatalytic Activity of Allophane – Wakefieldite-(Ce) Composite

In this study, highly adsorptive mechanically-mixed and as-synthesized allophane–wakefieldite-(Ce) composites were prepared by mechanical mixing and hydrothermal synthesis, respectively. The results from X-ray diffraction and Raman spectroscopy analyses show that the mechanically-mixed composite has higher crystallinity than the as-synthesized composite. The nanoparticles of wakefieldite-(Ce) were homogenously distributed with allophane in the as-synthesized composite. The specific surface areas of the mechanically-mixed and as-synthesized composites are 164 m2/g and 191 m2/g, respectively. The photocatalytic activity of the samples was evaluated for the degradation of acetaldehyde (AcH) gas under visible light. Both composites demonstrated higher photocatalytic activity than individual wakefieldite-(Ce) and allophane because allophane in the composites played an important role in the adsorption of acetaldehyde gas molecules and the mediation between the gas phase and the wakefieldite-(Ce) surface.