Rationalization of Interactions in Precious Metal/Ceria Catalysts Using the d-Band Center Model
Rationalization of Interactions in Precious Metal/Ceria Catalysts Using the d-Band Center Model
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DOI：
10.1002/anie.201300130
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发表时间：
2013-07-22
影响因子：
16.6
通讯作者：
Collier, P.
中科院分区：
文献类型：
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作者：
Acerbi, N.;Tsang, S. C. Edman;Collier, P.
由贵金属 (PM) 和二氧化铈组成的催化剂广泛用于多相催化，例如三效催化转化器、[1] 固体氧化物燃料电池、[1] 水煤气变换 [2] 和 CO 氧化等应用。过去，PM 和二氧化铈之间的特殊协同作用通常用“强金属-载体相互作用”(SMSI)[4] 或 H2 溢出来解释。[5]然而，Campbell 最近创造了术语“电子金属-载体相互作用”(EMSI)，[6] 更具体地描述了通常出色的催化活性的根本原因，这是由于高度分散的 PM 纳米粒子和具有高表面积的二氧化铈之间的高度接触造成的。Tauster 等人在研讨会论文中首次报道了 SMSI 效应，[7] 他们发现 H2 化学吸附能力的丧失 PM/TiO2 催化剂（Pt、Pd、Rh、Ru、Ir 或 Os），经过高温处理。这种效应可以通过在 O2 中加热来逆转，从而恢复催化剂的 H2 化学吸附行为。 [7]解释这种效应的第一个假设是，金属的电荷状态通过与下方载体的电子相互作用而改变，从而导致 H2 化学吸附能力的改变，这也导致金属催化性能的变化。 [8]然而，后来的模型建立了部分还原的 TiOx 物质对贵金属的部分覆盖的概念，导致 H2 化学吸附位点的阻塞。与 PM/TiO2 相比，PM/CeO2 的 SMSI 效应通常会导致催化活性增强，尽管暴露的 PM 表面积可能会大幅减少。 [3]对于 PM 与氧化还原活性氧化物（包括二氧化铈）接触的各种催化材料，可靠的
Catalysts consisting of precious metals (PMs) and ceria are widely used in heterogeneous catalysis, for example in applications such as three-way catalytic converters,[1] solid oxide fuel cells,[1] water–gas shift,[2] and CO oxidation.[3] In the past, the special synergy between PMs and ceria has most often been explained in terms of either “strong metal–support interaction”(SMSI)[4] or H2 spillover.[5] However, Campbell has recently coined the term “electronic metal–support interaction”(EMSI),[6] a more specific description of the underlying cause for the often outstanding catalytic activity, which results from a high degree of contact between highly dispersed PM nanoparticles and ceria with a high surface area.The SMSI effect was first reported in a seminar paper by Tauster et al.,[7] who found a loss of the ability for H2 chemisorption for PM/TiO2 catalysts (Pt, Pd, Rh, Ru, Ir or Os), when these were treated at high temperatures. This effect could be reversed by heating in O2, which restored the H2-chemisorption behavior of the catalyst.[7] One of the first hypotheses for explaining this effect was that the charge state of the metal was altered by the interaction with the electrons from the support underneath, thus leading to a modification of the ability for H2 chemisorption, which also brought about a change in the catalytic properties of the metal.[8] However, later models established the concept of fractional coverage of the noble metal by partially reduced TiOx species, leading to the blocking of sites for H2 chemisorption. In contrast to PM/TiO2, the SMSI effect for PM/CeO2 generally results in enhanced catalytic activity, even though the exposed PM surface area may be substantially reduced.[3] For a broad range of catalytic materials in which the PM is in contact with a redox-active oxide (including ceria), a reliable