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Understanding the Roles of Electrogenerated Co 3+ and Co 4+ in Selectivity‐Tuned 5‐Hydroxymethylfurfural Oxidation
Author(s) -
Deng Xiaohui,
Xu GeYang,
Zhang YueJiao,
Wang Lei,
Zhang Jiujun,
Li JianFeng,
Fu XianZhu,
Luo JingLi
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202108955
Subject(s) - chemistry , oxidizing agent , electrocatalyst , electrochemistry , hydroxymethyl , catalysis , selectivity , carboxylate , reaction mechanism , kinetics , product distribution , redox , combinatorial chemistry , photochemistry , inorganic chemistry , organic chemistry , electrode , physics , quantum mechanics
The Co‐based electrocatalyst is among the most promising candidates for electrochemical oxidation of 5‐hydroxymethylfurfural (HMF). However, the intrinsic active sites and detailed mechanism of this catalyst remains unclear. We combine experimental evidence and a theoretical study to show that electrogenerated Co 3+ and Co 4+ species act as chemical oxidants but with distinct roles in selective HMF oxidation. It is found that Co 3+ is only capable of oxidizing formyl group to produce carboxylate while Co 4+ is required for the initial oxidation of hydroxyl group with significantly faster kinetics. As a result, the product distribution shows explicit dependence on the Co oxidation states and selective production of 5‐hydroxymethyl‐2‐furancarboxylic acid (HMFCA) and 2,5‐furandicarboxylic acid (FDCA) are achieved by tuning the applied potential. This work offers essential mechanistic insight on Co‐catalyzed organic oxidation reactions and might guide the design of more efficient electrocatalysts.