在MoS2上电化学二演变的自由能障碍反应机制
Journal of the American Chemical Society
|May 6, 2015
概括
密度函数理论计算显示,MoS2上的演变反应 (HER) 主要遵循沃尔默-海洛夫斯基机制. 专注于降低金属化物反应屏障是设计更具反应性的MoS2催化剂的关键.
科学领域:
- 计算化学的计算化学
- 材料科学 材料科学 材料科学
- 电化学 电化学 电化学
背景情况:
- 二硫化物 (MoS2) 是演化反应 (HER) 的一个有希望的催化剂.
- 了解反应路径和能量障碍对于优化催化剂性能至关重要.
研究的目的:
- 用理论计算来确定 HER 在 MoS2 上的反应途径和障碍物.
- 在MoS2.2上确定HER的关键中间体和速率决定步骤.
主要方法:
- 密度函数理论 (DFT) 使用M06L函数的计算.
- 包含Poisson-Boltzmann解法模型的方法.
- 使用了周期性2D板和Mo10S21集群模型.
主要成果:
- 伏尔默-海洛夫斯基机制涉及化的质子化,其计算的自由能量屏障为17.9 kcal/mol.
- 这一障碍与实验估计很好地一致,表明其意义.
- 在Mo位点的质突比在S位点的质突更有利.
- 沃尔默-塔菲尔机制的预测屏障为22.6千卡/毫升.
- 硫键能量不是关键参数;动力障碍是更相关的描述因素.
结论:
- 在MoS2上,HER通过Volmer-Heyrovsky机制进行.
- 动力障碍,而不是平衡热力学,应该指导催化剂设计.
- 降低金属化物和之间的反应屏障对于提高MoS2催化剂反应性至关重要.
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