H2-D2 交换活动和Ag的电子结构 Pd1- 合金催化剂跨越组成空间
Nicholas Golio1, Irem Sen1, Xiaoxiao Yu1
1Department of Chemical Engineering and W.E. Scott Institute for Energy Innovation, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
这项研究研究了H2-D2交换反应的Ag-Pd合金催化剂. 在富含的表面上观察到高活性,这表明域上发生交换.
科学领域:
- 表面科学是一门学科.
- 催化剂是一种催化剂.
- 材料科学 材料科学 材料科学
背景情况:
- 计算研究揭示了催化剂描述符和反应障碍之间的线性缩放关系.
- 对催化剂活性,电子结构和合金组成的实验研究对于理解催化机制至关重要.
- Ag-Pd合金薄膜为研究催化中的结构-活性关系提供了一个可调的平台.
研究的目的:
- 实验研究催化剂活性,电子结构和Ag-Pd合金中的合金组成之间的关系.
- 为了同时测量100种合金组合物的稳定状态H2-D2交换动力学.
- 作为合金组成的函数,确定吸附,脱附和扩散的激活能量障碍.
主要方法:
- 采用银合金合金薄膜 (CSAF) 和多通道反应堆阵列.
- 在大气压和不同温度 (333-593 K) 下测量了稳定状态H2-D2交换动力学.
- 采用X射线光电子光谱 (XPS) 来描述表面组成和电子结构.
主要成果:
- 对于H2-D2交换的催化剂活性在纯 (Pd) 上是最高的,并且随着银 (Ag) 含量的增加而下降,在Pd度低于0.58.8的情况下消失.
- 价值带能量 (ε̅v) 与组成线性转移,从 -6.2 eV (Ag) 到 -3.4 eV (Pd).
- 双地表 (2H') 机制预测了Pd丰富的催化剂的吸附 (0-10 kJ/mol) 的低激活障碍,以及对脱附 (30-65 kJ/mol) 和扩散 (20-30 kJ/mol) 的中等激活障碍.
结论:
- 由于强大的H2-Pd相互作用,H2-D2交换主要发生在散装类Pd域上.
- 随着Pd含量下降,观察到的催化活性下降归因于表面Pd的可用性减少.
- 富含Pd的合金的动力参数表明一个一致的机制,随着Ag含量的上升,脱落和扩散障碍的潜在微小增加.
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