Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, China.
College of Materials, State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Fujian Key Laboratory of Advanced Materials, College of Energy, Xiamen University, Xiamen, China.
Angew Chem Int Ed Engl. 2021 Sep 6;60(37):20535-20542. doi: 10.1002/anie.202108955. Epub 2021 Aug 9.
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 and Co species act as chemical oxidants but with distinct roles in selective HMF oxidation. It is found that Co is only capable of oxidizing formyl group to produce carboxylate while Co 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.
钴基电催化剂是最有前途的用于 5-羟甲基糠醛（HMF）电化学氧化的候选催化剂之一。然而，该催化剂的本征活性位点和详细的反应机制仍不清楚。我们结合实验证据和理论研究表明，电生成的 Co 和 Co 物种作为化学氧化剂，但在选择性 HMF 氧化中具有不同的作用。研究发现，Co 只能将甲酰基氧化为羧酸盐，而 Co 则需要用于羟基的初始氧化，其动力学速度明显更快。因此，产物分布明显依赖于 Co 的氧化态，通过调节施加的电势可以选择性地生成 5-羟甲基-2-糠酸（HMFCA）和 2,5-呋喃二甲酸（FDCA）。这项工作为 Co 催化的有机氧化反应提供了重要的机理见解，并可能指导更高效电催化剂的设计。
