Li Jing, Li Chunsong, Hou Jiajie, Gao Wenqiang, Chang Xiaoxia, Lu Qi, Xu Bingjun
State Key Laboratory of Chemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
J Am Chem Soc. 2022 Nov 9;144(44):20495-20506. doi: 10.1021/jacs.2c09378. Epub 2022 Oct 26.
Understanding of the reaction network of Cu-catalyzed CO/CO electroreduction reaction [CORR] remains incomplete despite intense research efforts. This is in part because the rate-determining step occurs early in the reaction network, leading to short lifetimes of subsequent surface-bound intermediates, the knowledge of which is key to selectivity control. In this work, we demonstrate that alkyl groups can effectively couple with surface intermediates in the Cu-catalyzed CORR and, for the first time, intercept elusive C and C intermediates. Combined reactivity data and in situ spectroscopic results demonstrated that surface-bound alkyl groups derived from the corresponding alkyl iodides are able to couple with adsorbed CO to form carboxylates and ketones via one and two successive nucleophilic attacks, respectively. Leveraging this new chemistry, CH ( ≤ 3) and CH ( ≤ 4) are intercepted and identified as precursors for methane and -propanol in the CORR, respectively. Importantly, reaction pathways leading to methane and C products are not intrinsically orthogonal, but their connection is mainly impeded by low coverages of energetic intermediates. This study shows that perturbing the reaction of interest by introducing a slightly interacting probe reaction network could be an effective and general strategy in mechanistic studies of catalytic reactions.
尽管进行了大量研究，但对铜催化的CO/CO₂ 电还原反应（CORR）的反应网络的理解仍不完整。部分原因是速率决定步骤发生在反应网络的早期，导致后续表面结合中间体的寿命较短，而了解这些中间体是控制选择性的关键。在这项工作中，我们证明了烷基可以在铜催化的CORR中与表面中间体有效偶联，并且首次捕获了难以捉摸的C₁和C₂中间体。结合反应活性数据和原位光谱结果表明，源自相应烷基碘化物的表面结合烷基能够与吸附的CO偶联，分别通过一次和两次连续的亲核攻击形成羧酸盐和酮。利用这种新化学方法，CH₄（≤ 3）和CH₃（≤ 4）被捕获并分别确定为CORR中甲烷和1-丙醇的前体。重要的是，导致甲烷和C₁产物的反应途径并非本质上正交，但其连接主要受到高能中间体低覆盖率的阻碍。这项研究表明，通过引入轻微相互作用的探针反应网络来扰动目标反应可能是催化反应机理研究中的一种有效且通用的策略。
