Electrocatalytic Molecular Editing as a New Paradigm for Rare-Earth Separation

Area of Science:

• Chemical Engineering
• Catalysis
• Separation Science

Background:

• Separating yttrium from lanthanides is difficult due to low extractant selectivity.
• Existing methods struggle with the intrinsic similarities between these elements.

Purpose of the Study:

• To develop a novel electrocatalytic method for site-selective functionalization of extractants.
• To enhance the selectivity of phosphinoyl phosphonic acid (PPPA) for yttrium separation.

Main Methods:

• Utilized an oxygen-vacancy-rich Bi2O3(S) catalyst for electrocatalytic oxygen reduction.
• Generated *OOH intermediates for in situ activation of PPPA at the α-methylene site.
• Employed cascade extraction to evaluate the modified extractant's performance.

Main Results:

• Achieved site-selective hydroxylation of PPPA, creating a derivative with enhanced yttrium coordination.
• Demonstrated significantly improved separation factors for yttrium over lanthanides.
• Mechanistic studies revealed the role of oxygen vacancies and interfacial electronic structure in stabilizing reactive intermediates.

Conclusions:

• Established a general paradigm for coupling electrocatalysis with molecular editing for separation chemistry.
• The developed method offers a new strategy to overcome selectivity limitations in rare-earth element separation.
• This approach provides a pathway for designing high-performance extractants for challenging separations.