水中毒物 H2 激活在 Au-TiO 接口 通过减缓 Au 和 Titania 之间的质子和电子转移
K B Sravan Kumar1,2, Todd N Whittaker1, Christine Peterson1
1Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States.
Journal of the American Chemical Society
|February 22, 2020
概括
水覆盖对氧化有显著影响,而不是黄金/二氧化催化剂. 观察到不同的明显激活能量,揭示了由水存在和金属支接口部位影响的激活的两种动态模式.
科学领域:
- 不同质的催化
- 表面化学
- 材料科学
背景情况:
- 了解活性位点动态对于改善催化性能至关重要.
- 在支持的黄金催化剂上氧化是一种具有复杂机制的重要反应.
研究的目的:
- 研究水覆盖对Au/TiO2催化剂的氧化动力学的影响.
- 阐明水中毒的机制及其对明显激活能量的影响.
主要方法:
- 在不同料水压力下确定明显激活能量 (E_app) 的Arrhenius研究.
- 恒定水覆盖实验以确定不同的运动模式.
- 密度函数理论 (DFT) 计算以建模反应热力学和机制.
- 在现场进行红外光谱,观察表面的重组.
主要成果:
- 确定了两种异质H2激活的动态模式:在金属支接口的直接激活 (E_app ~ 25kJ/mol) 和通过水的激活 (E_app ~ 45kJ/mol).
- 水覆盖显著改变了活跃的金属支接口位数,影响了观察到的动力学.
- DFT计算表明水的热力学效应较小,但在H2吸附过程中显示出显著的TiO2支重组.
- 一个水单层增加了H2解离激活屏障约0.2 eV,符合实验结果.
结论:
- 水通过减缓质子转移,增加过渡状态的能量.
- TiO2支的动态重组和不同的金属支接口位密度是观察到的动力复杂性的关键因素.
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