Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115, USA.
National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA.
Angew Chem Int Ed Engl. 2017 Dec 4;56(49):15594-15598. doi: 10.1002/anie.201708484. Epub 2017 Nov 8.
Realization of the hydrogen economy relies on effective hydrogen production, storage, and utilization. The slow kinetics of hydrogen evolution and oxidation reaction (HER/HOR) in alkaline media limits many practical applications involving hydrogen generation and utilization, and how to overcome this fundamental limitation remains debatable. Here we present a kinetic study of the HOR on representative catalytic systems in alkaline media. Electrochemical measurements show that the HOR rate of Pt-Ru/C and Ru/C systems is decoupled to their hydrogen binding energy (HBE), challenging the current prevailing HBE mechanism. The alternative bifunctional mechanism is verified by combined electrochemical and in situ spectroscopic data, which provide convincing evidence for the presence of hydroxy groups on surface Ru sites in the HOR potential region and its key role in promoting the rate-determining Volmer step. The conclusion presents important references for design and selection of HOR catalysts.
氢能经济的实现依赖于有效的制氢、储氢和用氢。在碱性介质中，析氢反应（HER）和氧化反应（HOR）的动力学缓慢，限制了许多涉及制氢和用氢的实际应用，如何克服这一基本限制仍存在争议。本文对碱性介质中代表性催化体系的 HOR 进行了动力学研究。电化学测量表明，Pt-Ru/C 和 Ru/C 体系的 HOR 速率与其氢结合能（HBE）解耦，这对当前流行的 HBE 机制提出了挑战。通过电化学和原位光谱数据的结合，验证了双功能机理，为在 HOR 电位区域表面 Ru 位上存在羟基基团及其在促进速率决定的 Volmer 步骤中的关键作用提供了令人信服的证据。该结论为 HOR 催化剂的设计和选择提供了重要参考。
