Electrolytic Synthesis of White Phosphorus is Promoted in Oxide-Deficient Molten Salts

24 November 2022, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


Elemental white phosphorus (P4) is a key feedstock for the entire phosphorus-derived chemicals industry, spanning everything from herbi-cides to food additives. The electrochemical reduction of phosphate salts could enable the sustainable production of P4; however, such electrosynthesis requires the cleavage of strong, inert P—O bonds. By analogy to the promotion of bond activation in aqueous electrolytes with high proton activity (Brønsted-Lowry acidity), we show that low oxide anion activity (Lux-Flood acidity) enhances P—O bond activa-tion in molten salt electrolytes. We develop electroanalytical tools to quantify the oxide dependence of phosphate reduction, and find that Lux acidic phosphoryl anhydride linkages enable selective, high-efficiency electrosynthesis of P4 at a yield of 95% faradaic efficiency. These fundamental studies provide a foundation that may enable the development of low-carbon alternatives to legacy carbothermal synthesis of P4.


molten-salt electrolysis
industrial decarbonization
phosphate salts
high-temperature electrochemistry
white phosphorus
P—O bond activation

Supplementary materials

Supplementary Materials for Efficient Electrosynthesis of White Phosphorus from Molten Condensed Phosphate Salts
This PDF file includes: Materials and Methods Supplementary Text Supplementary References Figs. S1 to S18 Tables S1 to S8


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