Journal Article

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

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

2024

Overview

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 research 1 – 4 , in which the classic model is to categorize active sites in terms of distinct surface motifs, such as terraces and steps 1 , 5 – 10 . However, such a simple categorization often leads to orders of magnitude errors in catalyst activity predictions and qualitative uncertainties of active sites 7 , 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. Stress release at stepped platinum surfaces is shown to influence the strain experienced by atoms near the steps, resulting in effects on the catalytic activity of the whole surface.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 119/118 / 639/638/161/886 / 639/638/77/886 / 639/638/77/887 / Adsorption / Catalysis / Catalysts / Catalytic activity / Chemical reactions / Compressive properties / Crystal surfaces / Humanities and Social Sciences / Intermediates / multidisciplinary / Optimization / Reaction intermediates / Science / Science & Technology - Other Topics / Science (multidisciplinary) / Single crystals