Selective Ethanol Oxidation to Acetaldehyde on Nanostructured Zeolitic Imidazolate Framework‐8‐Wrapped ZnO Photothermocatalyst Thin Films
Hao Wu, Tze Hao Tan, Rugeng Liu, Hsien‐Yi Hsu, Yun Hau Ng
Abstract
Photothermocatalytic ethanol oxidation to acetaldehyde offers an alternative technology in synthesizing high‐value‐added chemicals. However, the practical application is hindered by the competition from overoxidation leading to complete mineralization. Herein, the 1D nanostructured ZnO@zeolitic imidazolate framework‐8 (ZIF‐8) composite is reported as an efficient photothermocatalyst, which shows improved conversion efficiency and high catalytic selectivity and durability compared with the parent ZnO nanorods, for continuous ethanol oxidation in a flow system. The ZnO@ZIF‐8 composite achieves a high selectivity of 91.5% toward acetaldehyde production. The underlying mechanism is probed using electrochemical impedance spectroscopy, N 2 adsorption–desorption isotherms, transient open‐circuit potential, and steady‐state and time‐resolved photoluminescence spectroscopy. Collectively, the probings show that the improved performance originates from 1) facilitated charge separation; 2) lowered oxidation potential holes; 3) enlarged surface area; and 4) preferred reaction routes. This work provides a new perspective for the design of a hybrid photothermocatalyst for selective solar energy conversion into desirable chemicals.