Issue 5, 2019

CuO/TiO2 heterojunction composites: an efficient photocatalyst for selective oxidation of methanol to methyl formate

Abstract

This study demonstrates the synthesis of an efficient photocatalyst, CuO/TiO2 heterojunction, for selective aerobic photo-oxidation of methanol to methyl formate. The CuO nanoparticles (size: 3.5 ± 1.0 nm) are particularly deposited at the {101} facet of anatase TiO2 nanosheets to minimize recombination of photo-generated electrons/holes. The photocatalysts are characterized by different methods, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy, and hydrogen temperature-programmed reduction (H2-TPR). The heterojunction catalysts exhibit an excellent photocatalytic performance under mild conditions (i.e., 25–45 °C and gas reactions under UV irradiation with a wavelength of 365 nm) for the selective photo-oxidation of methanol using 0.5 vol% oxygen (O2) as an oxidizing agent. The 5 wt% CuO/TiO2 photocatalyst exhibits a decent 95% methanol conversion with over 85% selectivity towards the formation of methyl formate. The by-product of the reaction is found to be merely CO2, which can be readily eliminated from the product. The formation rate for the methyl formate is 10.8 mmol g−1 h−1 at 25 °C, which is considerably higher than that for the corresponding CuO and TiO2 nanosheets as well as for conventional catalysts. The superior catalytic activity of the CuO/TiO2 is associated with its unique electronic structure and the synergistic effects at the interface of the photocatalysts' components. The results of this study offer guidelines for design of a new synthetic strategy for preparation of efficient photocatalysts for selective oxidation of methanol to methyl formate and related reactions.

Graphical abstract: CuO/TiO2 heterojunction composites: an efficient photocatalyst for selective oxidation of methanol to methyl formate

Article information

Article type
Paper
Submitted
29 Way 2018
Accepted
22 Kax 2018
First published
24 Kax 2018

J. Mater. Chem. A, 2019,7, 2253-2260

CuO/TiO2 heterojunction composites: an efficient photocatalyst for selective oxidation of methanol to methyl formate

Q. Shi, G. Ping, X. Wang, H. Xu, J. Li, J. Cui, H. Abroshan, H. Ding and G. Li, J. Mater. Chem. A, 2019, 7, 2253 DOI: 10.1039/C8TA09439J

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