Breaking the scaling relations for efficient N2-to-NH3 conversion by a bowl active site design: Insight from LaRuSi and isostructural electrides

The design of optimal heterogeneous catalysts for N2-to-NH3 conversion is often dictated by the scaling relations, which result in a volcano curve that poses a limit on the catalytic performance. Herein, we reveal a bowl active site that can break the scaling relations, through investigating the catalytic mechanisms of N2-to-NH3 conversion on the lanthanide intermetallic electride catalyst LaRuSi by first-principles modeling. This bowl active site, composed of four surface La cations and one subsurface Si atom rich in electrons, plays the key role in enabling efficient catalysis. With adaptive electrostatic and orbital interactions, the bowl active site promotes the adsorption and activation of N2 that delivers facile cleavage of N–N bond, while destabilizes the adsorptions of *NHx (x = 1, 2, 3) species, which facilitates the release of the final NH3 product. By comparison with other electride catalysts isostructural to LaRuSi, we confirm the breaking of scaling relations between the adsorptions of *NHx species and that of *N on the bowl active site. Thus, this bowl active site presents a design concept that breaks the scaling relations for highly efficient heterogeneous catalysis of N2-to-NH3 conversion.