Structural defects induced in ETS-10 by postsynthesis treatment with H2O2 solution
Chemistry of Materials 18(16): 3813-3820
The presence of structural defects in ETS-10 titanosilicate plays an important role in its adsorption capacity and catalytic activity, e. g., in photocatalysis of organic molecules. In the present work, we used postsynthesis treatments with hydrogen peroxide to introduce different levels of defects in the ETS-10 structure. The number of defects induced was dependent on the concentration of H2O2 and exposition time. These treatments led to a partial removal of Ti atoms, resulting in the interruption of titania chains and the consequent formation of larger micropores (supermicropores) without substantial degradation of crystallinity. High-resolution sorption experiments indicate that the micropore volume was slightly increased after H2O2 treatment, and a bimodal pore size distribution was observed for the modified ETS-10 samples. The presence of supermicropores in the structure was directly visualized by transmission electron microscopy. The interruption of Ti-O-Ti chains and the formation of new accessible Ti centers was indicated by spectroscopic techniques such as Raman, DRIFT, and DR UV-vis spectroscopy.