Weerasooriya Ravindra B, Gesiorski Jonathan L, Alherz Abdulaziz, Ilic Stefan, Hargenrader George N, Musgrave Charles B, Glusac Ksenija D
Department of Chemistry, University of Illinois at Chicago, 845 W Taylor Street, Chicago, Illinois 60607, United States.
Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 Cass Ave., Lemont, Illinois 60439, United States.
J Phys Chem Lett. 2021 Mar 11;12(9):2306-2311. doi: 10.1021/acs.jpclett.0c03662. Epub 2021 Mar 2.
Selective reduction of CO to formate represents an ongoing challenge in photoelectrocatalysis. To provide mechanistic insights, we investigate the kinetics of hydride transfer (HT) from a series of metal-free hydride donors to CO. The observed dependence of experimental and calculated HT barriers on the thermodynamic driving force was modeled by using the Marcus hydride transfer formalism to obtain the insights into the effect of reorganization energies on the reaction kinetics. Our results indicate that even if the most ideal hydride donor were discovered, the HT to CO would exhibit sluggish kinetics (<100 turnovers per second at -0.1 eV driving force), indicating that the conventional HT may not be an appropriate mechanism for solar conversion of CO to formate. We propose that the conventional HT mechanism should not be considered for CO reduction catalysis and argue that the orthogonal HT mechanism, previously proposed to address thermodynamic limitations of this reaction, may also lead to lower kinetic barriers for CO reduction to formate.
在光电催化中，将一氧化碳选择性还原为甲酸仍是一个持续存在的挑战。为了提供机理见解，我们研究了一系列无金属氢化物供体向一氧化碳的氢化物转移（HT）动力学。通过使用马库斯氢化物转移形式理论对实验和计算得到的氢化物转移势垒对热力学驱动力的观测依赖性进行建模，以深入了解重组能对反应动力学的影响。我们的结果表明，即使发现了最理想的氢化物供体，向一氧化碳的氢化物转移也将表现出缓慢的动力学（在-0.1 eV驱动力下每秒周转数<100），这表明传统的氢化物转移可能不是将一氧化碳太阳能转化为甲酸的合适机制。我们提出，在一氧化碳还原催化中不应考虑传统的氢化物转移机制，并认为先前为解决该反应的热力学限制而提出的正交氢化物转移机制，也可能导致一氧化碳还原为甲酸的动力学势垒更低。
