(689c) Diatomic Catalysts: Controlled Synthesis and Applications in Oxygen Reduction Reactions.

Heterogeneous catalysts containing diatomic sites are often hypothesized to have distinctive reactivity due to synergistic effects, but there are limited approaches that enable the convenient production of diatomic catalysts (DACs) with diverse metal combinations. In this report, we present a general synthetic strategy for constructing a DAC library across a wide spectrum of homonuclear (Fe₂, Co₂, Ni₂, Cu₂, Mn₂, and Pd₂) and heteronuclear (Fe−Cu, Fe−Ni, Cu−Mn, and Cu−Co) bimetal centers. This strategy is based on an encapsulation−pyrolysis approach, wherein a porous material-encapsulated macrocyclic complex mediates the structure of DACs by preserving the main body of the molecular framework during pyrolysis.

We take the oxygen reduction reaction (ORR) as an example to show that this DAC library can provide great opportunities for electrocatalyst development by unlocking unique reaction pathways. Among all investigated sites, Fe−Cu diatomic sites possess exceptional high durability for four-electron ORR because the Fe−Cu pairs can steer elementary steps in the catalytic cycle and suppress the troublesome Fenton-like reactions. We also report a diatomic cobalt catalyst for two-electron ORR to efficiently produce hydrogen peroxide at industrial-relevant current densities (200−400 mA cm^−2) in acid media.