Impact of Coordination Environment for Designing Ru-Based Alloy Catalysts for Ammonia Decomposition.

Alloying is an effective strategy to modulate a metal catalyst's electronic structure and optimize its performance, but developing a fundamental design principle has been challenging due to the geometric and electronic disturbance between the active atom and its microenvironment. We introduce a descriptor, coordination impact, which combines ligand and structural effects to quantify the influence of neighboring atoms on the electronic structure of the adsorption site. Using first-principles simulations, microkinetic model and experimental data, we thoroughly examine the catalytic performance of RuM alloys for ammonia decomposition using this descriptor. The microenvironment influences the activity of adsorption site by modulating the orbital interaction between the active site and adsorbate. The descriptor follows a volcano-shaped relationship with reaction rates, consistent with Sabatier principle, and the predicted rates are experimentally validated.