Activating C-H Bonds by Tuning Fe Sites and an Interfacial Effect for Enhanced Methanol Oxidation.

Huang, Sheng; Feng, Feng; Huang, Rong-Ting; Ouyang, Ting; Liu, Jinlong; Liu, Zhao-Qing · Adv Mater · 2022

basic_science · Level V

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Abstract

The interaction mechanism between the reacting species and the active site of α-Fe<sub>2</sub> O<sub>3</sub> -based photoanodes in photoelectrochemical methanol conversion reaction is still ambiguous. Herein, a simple two-step strategy is demonstrated to fabricate a porous α-Fe<sub>2</sub> O<sub>3</sub> /CoFe<sub>2</sub> O<sub>4</sub> heterojunction for the methanol conversion reaction. The influence of the electronic structure of active site and interfacial effect on the reaction are investigated by constructing two different FeO<sub>6</sub> octahedral configurations and heterogeneous structures. The optimal sample ZnFeCo-2 affords high photocurrent density of 1.17 mA cm<sup>-2</sup> at 0.5 V vs Ag/AgCl, which is 3.2 times than that of ZnFe (0.37 mA cm<sup>-2</sup> ). Meanwhile, the ZnFeCo-2 also exhibits 97.8% Faraday efficiency of CH<sub>3</sub> OH to HCHO, and long-term stability over 40 h. Furthermore, density functional theory calculations reveal that the heterostructured α-Fe<sub>2</sub> O<sub>3</sub> /CoFe<sub>2</sub> O<sub>4</sub> with favorable electron transfer effectively lowers methanol adsorption, C-H bond activation, and HCHO desorption energy relative to the pristine α-Fe<sub>2</sub> O<sub>3</sub> , resulting in excellent methanol conversion efficiency.