Catalytic efficiency can be generally enhanced by cultivating active atoms on a catalyst, while reaction channel manipulation is extremely challenging. Here, we employ a 2,5-pyrazinedicarboxylic acid (denoted as pdc) linker to construct a Cu5-pdc-Cu5 catalyst (that is, Cu5Cu5(TC4A)4(pdc)Cl2) by bridging two Cu5(TC4A)2Cl2 (TC4A = 4-tert-butylthiacalix4arene) clusters, and propose blocking only two active atoms on this catalyst to achieve exceptionally catalytic performance for ammonia synthesis. This unforeseen performance of the catalyst, which deviates from the pursuit of more active sites, arises from the mobility adjustment of the reaction species among adjacent active sites by dredging the jammed sites for water activation. The specially designed linker of the Cu5-pdc-Cu5 catalyst purposefully shields two sites for nitrate activation, thereby enabling three protons originating from water activation to react with nitrate awaited on the inverted contraposition of the two sites. Consequently, the reduction steps from nitrate to ammonia over the Cu5-pdc-Cu5 catalyst are minimized, naturally promoting the efficiency of ammonia production and outperforming other Cu-based catalysts reported. The blocking-active-site approach offers a novel conceptual perspective for designing high-performance catalysts.
Tian et al. (Thu,) studied this question.