Reaction Parameters Influencing Cobalt Hydride Formation Kinetics: Implications for Benchmarking H2-Evolution Catalysts
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- 作者：Noémie ElgrishiDaniel A. Kurtz ; Jillian L. Dempsey
- 刊名：Journal of the American Chemical Society
- 出版年：2017
- 出版时间：January 11, 2017
- 年：2017
- 卷：139
- 期：1
- 页码：239-244
- 全文大小：392K
- ISSN：1520-5126
文摘
The need for benchmarking hydrogen evolution catalysts has increasingly been recognized. The influence of acid choice on activity is often reduced to the overpotential for catalysis. Through the study of a stable cobalt hydride complex, we demonstrate the influence of acid choice, beyond pKa, on the kinetics of hydride formation. A linear free energy relationship between acid pKa and second-order rate constants is observed for weaker acids. For stronger acids, however, further increases in pKa do not correlate to increases in rate constants. Further, steric bulk around the acidic proton is shown to influence rate constants dramatically. Together, these observations reveal the complex factors dictating catalyst performance.