There is wide interest in developing accurate theories for predicting rates of chemical reactions that occur at metal surfaces, especially for applications in industrial catalysis. Conventional methods contain many approximations that lack experimental validation. In practice, there are few reactions where sufficiently accurate experimental data exist to even allow meaningful comparisons to theory. Here, we present experimentally derived thermal rate constants for hydrogen atom recombination on platinum single-crystal surfaces, which are accurate enough to test established theoretical approximations. A quantum rate model is also presented, making possible a direct evaluation of the accuracy of commonly used approximations to adsorbate entropy. We find that neglecting the wave nature of adsorbed hydrogen atoms and their electronic spin degeneracy leads to a 10× to 1000× overestimation of the rate constant for temperatures relevant to heterogeneous catalysis. These quantum effects are also found to be important for nanoparticle catalysts.

中文翻译：

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金属表面热反应速率的量子效应

人们对开发准确的理论来预测金属表面发生的化学反应的速率有着广泛的兴趣，特别是在工业催化中的应用。传统方法包含许多缺乏实验验证的近似值。在实践中，很少有反应存在足够准确的实验数据，甚至可以与理论进行有意义的比较。在这里，我们提出了铂单晶表面上氢原子复合的实验推导的热速率常数，其准确度足以测试已建立的理论近似值。还提出了一个量子速率模型，可以直接评估吸附熵的常用近似值的准确性。我们发现，忽略吸附氢原子的波动性质及其电子自旋简并性会导致对与多相催化相关的温度的速率常数高估 10 倍至 1000 倍。这些量子效应也被发现对纳米粒子催化剂很重要。