Engineering catalytic sites at the atomic level provides an opportunity to understand the catalyst’s active sites, which is vital to the development of improved catalysts. Here we show a reliable and tunable polyoxometalate template-based synthetic strategy to atomically engineer metal doping sites onto metallic 1T-MoS 2 , using Anderson-type polyoxometalates as precursors. Benefiting from engineering nickel and oxygen atoms, the optimized electrocatalyst shows great enhancement in the hydrogen evolution reaction with a positive onset potential of ~ 0 V and a low overpotential of −46 mV in alkaline electrolyte, comparable to platinum-based catalysts. First-principles calculations reveal co-doping nickel and oxygen into 1T-MoS 2 assists the process of water dissociation and hydrogen generation from their intermediate states. This research will expand on the ability to improve the activities of various catalysts by precisely engineering atomic activation sites to achieve significant electronic modulations and improve atomic utilization efficiencies.

Recently, phenanthroline-based ligands have received increasing attention due to their excellent separation capabilities for trivalent actinides over lanthanide. In this work, we designed a soft–hard donor combined tetradentate phenanthroline-based extractant, tetraethyl (1,10-phenanthrolin-2,9-diyl)­phosphonate (C2-POPhen), for the selective separation of trivalent Am­(III) over Ln­(III) from HNO3 media. The solvent extraction and complexation behaviors of Am­(III) and Ln­(III) by C2-POPhen were investigated both experimentally and theoretically. C2-POPhen could selectively extract Am­(III) over Eu­(III) with an extremely fast extraction kinetics. NMR titration studies suggest that only 1:1 complexes of Ln­(III) with C2-POPhen formed in CH3OH in the presence of a significant amount of nitrate, while both 1:1 and 2:1 complexes species could form between C2-POPhen and Ln­(III) perchlorate in CH3OH without nitrate ions. The stability constants for the complexation of Am­(III) and Ln­(III) with C2-POPhen in CH3OH were determined by spectrophotometric titrations and the Am­(III) complexes are approximately 1 order of magnitude stronger than those of Ln­(III), which is consistent with the extraction results. Theoretical calculations indicate that the Am–N bonds in Am/C2-POPhen complexes possess more covalent characters than the Eu–N bonds in Eu/C2-POPhen complexes, shedding light on the underlying chemical force responsible for the Am/Eu selectivity by C2-POPhen. This work represents the first report utilizing phenanthroline-based phosphonate ligands for selective separation of actinides from highly acidic solutions.

The separation and complexation mechanisms of actinide(iii) and lanthanide(iii) with a new phenanthroline-derived phosphonate ligand were studied experimentally and theoretically.