美国普渡大学Zeng, Zhenhua研究团队报道了应力释放驱动台阶状Pt表面的位点特异性反应性。相关研究成果于2024年2月28日发表在《自然》。

多相催化剂被广泛用于促进化学反应。尽管已知化学反应通常发生在催化剂表面，但只有特定的表面位点具有高催化活性。因此，识别活性位点并最大限度地提高其存在性是催化研究的核心，其中经典模型是根据不同的表面基序对活性位点进行分类，如阶地和台阶。然而，这种简单的分类往往会导致催化剂活性预测的数量级误差，和活性位点的定性不确定性，从而限制了催化剂设计的机会。

该文中，以台阶状Pt（111）表面和电化学氧还原反应（ORR）为例，证明了较大误差和不确定性的根本原因，是忽略了由表面应力释放驱动的原子位点反应性的简化分类。具体而言，台阶处的表面应力释放引入了不均匀的应变场，压缩率高达5.5%，导致具有相同局部配位的阶地原子具有不同的电子结构和反应性，并导致ORR活性的原子位点特异性增强。

对于台阶边缘两侧的台阶原子，其增强程度高达台阶中间原子的增强程度的50倍，这能够通过改变台阶宽度或控制外部应力来控制ORR反应性。因此，上述协同作用的发现为对催化活性原子位点的基本理解，和多相催化剂的设计原理提供了新的视角。

附：英文原文

Title: Site-specific reactivity of stepped Pt surfaces driven by stress release

Author: Liu, Guangdong, Shih, Arthur J., Deng, Huiqiu, Ojha, Kasinath, Chen, Xiaoting, Luo, Mingchuan, McCrum, Ian T., Koper, Marc T. M., Greeley, Jeffrey, Zeng, Zhenhua

Issue&Volume: 2024-02-28

Abstract: Heterogeneous catalysts are widely used to promote chemical reactions. Although it is known that chemical reactions usually happen on catalyst surfaces, only specific surface sites have high catalytic activity. Thus, identifying active sites and maximizing their presence lies at the heart of catalysis research1,2,3,4, in which the classic model is to categorize active sites in terms of distinct surface motifs, such as terraces and steps1,5,6,7,8,9,10. However, such a simple categorization often leads to orders of magnitude errors in catalyst activity predictions and qualitative uncertainties of active sites7,8,11,12, thus limiting opportunities for catalyst design. Here, using stepped Pt(111) surfaces and the electrochemical oxygen reduction reaction (ORR) as examples, we demonstrate that the root cause of larger errors and uncertainties is a simplified categorization that overlooks atomic site-specific reactivity driven by surface stress release. Specifically, surface stress release at steps introduces inhomogeneous strain fields, with up to 5.5% compression, leading to distinct electronic structures and reactivity for terrace atoms with identical local coordination, and resulting in atomic site-specific enhancement of ORR activity. For the terrace atoms flanking both sides of the step edge, the enhancement is up to 50 times higher than that of the atoms in the middle of the terrace, which permits control of ORR reactivity by either varying terrace widths or controlling external stress. Thus, the discovery of the above synergy provides a new perspective for both fundamental understanding of catalytically active atomic sites and design principles of heterogeneous catalysts.

DOI: 10.1038/s41586-024-07090-z

Source: https://www.nature.com/articles/s41586-024-07090-z