Huang Jianan Erick, Chen Yiqing, Ou Pengfei, Ding Xueda, Yan Yu, Dorakhan Roham, Lum Yanwei, Li Xiao-Yan, Bai Yang, Wu Chengqian, Fan Mengyang, Lee Mi Gyoung, Miao Rui Kai, Liu Yanjiang, O'Brien Colin, Zhang Jinqiang, Tian Cong, Liang Yongxiang, Xu Yi, Luo Mingchuan, Sinton David, Sargent Edward H
Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
School of Material Science and Engineering, Peking University, Beijing 100871, China.
J Am Chem Soc. 2024 Mar 27;146(12):8641-8649. doi: 10.1021/jacs.4c00312. Epub 2024 Mar 12.
Renewable-energy-powered electrosynthesis has the potential to contribute to decarbonizing the production of propylene glycol, a chemical that is used currently in the manufacture of polyesters and antifreeze and has a high carbon intensity. Unfortunately, to date, the electrooxidation of propylene under ambient conditions has suffered from a wide product distribution, leading to a low faradic efficiency toward the desired propylene glycol. We undertook mechanistic investigations and found that the reconstruction of Pd to PdO occurs, followed by hydroxide formation under anodic bias. The formation of this metastable hydroxide layer arrests the progressive dissolution of Pd in a locally acidic environment, increases the activity, and steers the reaction pathway toward propylene glycol. Rh-doped Pd further improves propylene glycol selectivity. Density functional theory (DFT) suggests that the Rh dopant lowers the energy associated with the production of the final intermediate in propylene glycol formation and renders the desorption step spontaneous, a concept consistent with experimental studies. We report a 75% faradic efficiency toward propylene glycol maintained over 100 h of operation.
可再生能源驱动的电合成有潜力助力丙二醇生产的脱碳，丙二醇是一种目前用于制造聚酯和防冻液且碳强度高的化学品。不幸的是，迄今为止，在环境条件下丙烯的电氧化存在产物分布广泛的问题，导致对所需丙二醇的法拉第效率较低。我们进行了机理研究，发现Pd会重构为PdO，随后在阳极偏压下形成氢氧化物。这种亚稳态氢氧化物层的形成阻止了Pd在局部酸性环境中的逐步溶解，提高了活性，并使反应路径转向丙二醇。Rh掺杂的Pd进一步提高了丙二醇的选择性。密度泛函理论（DFT）表明，Rh掺杂剂降低了丙二醇形成过程中最终中间体生成所关联的能量，并使解吸步骤自发进行，这一概念与实验研究一致。我们报告了在100小时的运行过程中，对丙二醇的法拉第效率保持在75%。
