Mechanical work makes important contributions to surface chemistry at steps.

Area of Science:

• Surface Science
• Materials Science
• Computational Chemistry

Background:

• The binding energy of adsorbates on late transition metals is traditionally explained by electronic factors, with tensile strain enhancing binding.
• The widely accepted electronic 'd-band' model predicts consistent trends for strain effects on flat surfaces.

Purpose of the Study:

• To investigate the influence of mechanical strain on adsorbate binding energies at stepped surfaces of late transition metals.
• To elucidate the underlying mechanisms responsible for strain-induced changes in binding energy, particularly at non-ideal surface sites.

Main Methods:

• Utilizing computational methods to model the interaction of adsorbates with strained late transition metal surfaces.
• Analyzing the contributions of both electronic and mechanical energy changes to the overall binding energy.

Main Results:

• Mechanical strain at stepped surfaces can lead to binding trends opposite to those observed on flat surfaces.
• A novel mechanical energy relaxation mechanism was identified, which can dominate over electronic effects.
• This mechanical effect challenges the predictions of the established 'd-band' model.

Conclusions:

• The findings highlight the critical role of mechanical energy relaxation in modifying adsorbate binding at stepped surfaces.
• The study demonstrates that strain effects on catalytic activity, exemplified by nickel methanation, can be significantly altered by these mechanical factors.
• This work necessitates a revised understanding of strain effects in heterogeneous catalysis, particularly for stepped surfaces.