Ti-containing hybrid mesoporous organosilicas as photocatalysts for H2 production from ethanol

A series of complex organic-inorganic mesoporous materials were successfully synthesized by a microwave-assisted method that allowed the preparation of periodic meso-porous organosilicas (PMOs) with Ti (IV) forming part of the structure (Ti-PMOs). Materials were characterized using N-2 adsorption-desorption isotherms, powder X-ray diffraction (XRD), transmission and high resolution transmission electron microscopy (TEM and HRTEM), Raman, infrared, UV-visible diffuse reflectance (UV-vis RDS), X-ray photoelectron (XPS), photoluminescence (PL) and electrochemical impedance (EIS) spectroscopy, and transient photocurrent measurements. Samples labeled Ti10-PMO, Ti20-PMO and Ti40-PMO (with Si/Ti molar ratio of about 10, 20 and 40), showed crystal-like characteristics and high specific surface area (742-829 m(2)g(-1)). Ti-PMOs were studied in the photocatalytic H-2 evolution from an aqueous ethanol solution under UV-visible irradiation. Ti-PMOs showed a better photocatalytic behavior than PMO and this is related with the presence of tetrahedral Ti(IV) in the PMOs network. Ti-PMOs displayed a lower barrier for the electron transfer and a more efficient charge separation than PMO. The highest H-2 production was obtained with Ti20-PMO photocatalyst; after 4 h of irradiation, 2042 mmol H-2 g(cat)(-1) were obtained, which was about 20 times higher than that obtained with a reference commercial TiO2 (P25). (C) 2021 The Authors. Published by Elsevier B.V.

Automated summary

A series of complex organic-inorganic mesoporous materials were successfully synthesized by a microwave-assisted method, characterized using various techniques. Ti-PMOs showed better photocatalytic properties compared to PMO due to the presence of tetrahedral Ti(IV). Among the samples, Ti20-PMO exhibited the highest H2 production in the photocatalytic reaction.