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. Here, we present a general synthetic strategy for constructing a DAC library across a wide spectrum of homonuclear (Fe 2 , Co 2 , Ni 2 , Cu 2 , Mn 2 , and Pd 2 ) 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 an unconventional reaction pathway. Among all investigated sites, Fe−Cu diatomic sites possess exceptional high durability for ORR because the Fe−Cu pairs can steer elementary steps in the catalytic cycle and suppress the troublesome Fenton-like reactions.

In this work, a tetradentate N,O-hybrid 2,9-bis­(diphenylphosphine oxide)-1,10-phenanthroline (Ph2-BPPhen) ligand was studied for the coextraction of trivalent f-block elements from nitric acid media. The extraction as well as the complexation behaviors of Ph2-BPPhen with f-block elements were thoroughly investigated using 31P and 1H NMR spectrometry, UV–vis spectrophotometry, single crystal X-ray diffraction, and density functional theoretical (DFT) calculation. Ph2-BPPhen exhibits remarkably extraction ability for both Am­(III) and Eu­(III) and more than 99.5% of Am­(III) and Eu­(III) were extracted from 1.0 M HNO3 solution. Slope analysis suggests that both 2:1 and 1:1 ligand/metal complexes were probably formed during the extraction. The 1:1 and 2:1 Ln­(III) complexes with Ph2-BPPhen were also identified in CH3OH solution by NMR spectrometry, and the stability constants were determined via UV–vis spectrophotometry. Structures of the 1:1 Eu­(Ph2-BPPhen)­(NO3)3 and Am­(Ph2-BPPhen)­(NO3)3 complexes were further elucidated by single X-ray crystallography and DFT calculations. The higher extractability of Ph2-BPPhen toward trivalent Am­(III) and Eu­(III) compared with the previously reported phenanthroline-derived amide and phosphonate ligands was attributed to the stronger affinity of the −PO­(R)2 group to metal ions. The results from this work indicate that the N,O-hybrid 1,10-phenanthroline derived phosphine oxide ligand can serve as a new and promising candidate for coextraction of trivalent f-block elements in the treatment of nuclear waste.

Remediation and reuse of discarded plastics can reduce their accumulation in the environment and bring energy savings for plastic production. Here we discover a binuclear zinc catalyst that features a biomimetic intramolecular pathway for polyester depolymerization, which not merely enables environmental degradation of PET but also affords industrial-scale PET recycling under relatively mild conditions. The binuclear catalyst delivers a speci c activity of 36 mg PET d -1 g catal -1 toward PET depolymerization at pH 8 and 40 o C, the very condition holding the possibility of naturally breaking down plastic waste. The structural stability of this synthetic catalyst allows it to work under wide operational conditions, resulting in a speci c activity of 577 g PET h -1 g catal -1 at pH 13 and 90 o C for centralized PET recycling. A closed-loop production of bottle-grade PET was also demonstrated. Besides, this catalyst is catalytically active toward a wide scope of substrates with high tolerance to additives and impurities.