厦门大学周至有团队报道了丙烯在电化学界面的氧化反应机理及选择性调节。相关研究成果发表在2022年11月7日出版的国际知名学术期刊《美国化学会杂志》。

丙烯的电化学转化是利用可再生电力制造商品化学品的一种有前途的技术。为了实现这一目标，研究人员仍然需要开发用于丙烯电氧化的高性能电催化剂，这高度依赖于在分子水平上理解反应机理。尽管在热催化条件下，丙烯在固体/气体界面上的氧化机理已经得到了很好的研究，但在电化学环境下，在固体/液体界面上仍然难以捉摸。

该文中，研究人员报道了丙烯在PdO/C和Pd/C催化剂上电氧化的机理研究，考虑到Pd基催化剂是最有前途的电催化体系之一。通过电化学原位衰减全反射傅里叶变换红外光谱，与传统的热催化相比，观察到了不同的反应路径，强调了丙烯可以在高于0.80V的电位下脱氢，并分别通过在PdO和Pd上的μ-C═CHCH3和μ3-η2-C═CHCH3构型强烈吸附。μ-C═CHCH3通过PdO上相邻的Pd和O原子上的桥键，并且可以通过直接从PdO中获取表面氧来进一步氧化，这通过H₂¹⁸O同位素编辑实验得到验证。PdO/C上的高表面氧含量导致将丙烯转化为丙二醇的转化频率比Pd/C上高3倍。

该发现突出了电化学环境下的不同反应途径，为设计下一代丙烯电氧化电催化剂提供了依据。

附：英文原文

Title: Reaction Mechanism and Selectivity Tuning of Propene Oxidation at the Electrochemical Interface

Author: Xiao-Chen Liu, Tao Wang, Zhi-Ming Zhang, Cong-Hua Yang, Lai-Yang Li, Shimiao Wu, Shunji Xie, Gang Fu, Zhi-You Zhou, Shi-Gang Sun

Issue&Volume: November 7, 2022

Abstract: Electrochemical conversion of propene is a promising technique for manufacturing commodity chemicals by using renewable electricity. To achieve this goal, we still need to develop high-performance electrocatalysts for propene electrooxidation, which highly relies on understanding the reaction mechanism at the molecular level. Although the propene oxidation mechanism has been well investigated at the solid/gas interface under thermocatalytic conditions, it still remains elusive at the solid/liquid interface under an electrochemical environment. Here, we report the mechanistic studies of propene electrooxidation on PdO/C and Pd/C catalysts, considering that the Pd-based catalyst is one of the most promising electrocatalytic systems. By electrochemical in situ attenuated total reflection Fourier transform infrared spectroscopy, a distinct reaction pathway was observed compared with conventional thermocatalysis, emphasizing that propene can be dehydrogenated at a potential higher than 0.80 V, and strongly adsorb via μ-C═CHCH3 and μ3-η2-C═CHCH3 configuration on PdO and Pd, respectively. The μ-C═CHCH3 is via bridge bonds on adjacent Pd and O atoms on PdO, and it can be further oxidized by directly taking surface oxygen from PdO, verified by the H218O isotope-edited experiment. A high surface oxygen content on PdO/C results in a 3 times higher turnover frequency than that on Pd/C for converting propene into propene glycol. This finding highlights the different reaction pathways under an electrochemical environment, which sheds light on designing next-generation electrocatalysts for propene electrooxidation.

DOI: 10.1021/jacs.2c09105

Source: https://pubs.acs.org/doi/10.1021/jacs.2c09105