Theoretical design principles of metal catalysts for selective ammonia oxidation from high throughput computation

Selective catalytic oxidation of ammonia (NH3-SCO) is a ubiquitous process in exhaust aftertreatment, yet making catalysts with high reactivity and selectivity at low working temperatures remains a great challenge, due to the trade-off between activity and selectivity under operating conditions. We present here a microkinetic-based high throughput computational study on ammonia selective oxidation catalysts and outline the basic requirements and design principles of a good NH3-SCO catalyst. The complete ammonia selective oxidation process is demonstrated on the low-index facets of representative metals (Ag, Au, Cu, Ir, Pd, Pt, Rh and Ru), and the NH3 oxidation rates, product selectivity and reactivity orders of different metallic catalysts are evaluated quantitatively. It is revealed that the binding abilities of N and O atoms could be used as effective descriptors of catalytic performance arising from the existence of linear scaling relations among surface adsorbates. The ruling laws of catalytic performance state that moderate N binding energy (-5.00 similar to -4.00 eV) exhibits the most favorable catalytic activity, on top of which strengthened O binding could further promote N-2 selectivity. Based on the guiding principles, a series of alloy systems are batch screened and some potential catalysts with good activity and selectivity are proposed. Our study lays out a general theoretical framework for the design of metallic catalysts and their property tuning for NH3-SCO.