Efficient Electrosynthesis of White Phosphorus from Molten Condensed Phosphate Salts

Elemental white phosphorus (P4) is a crucial feedstock for the entire phosphorus-derived chemicals industry, spanning everything from herbicides to food additives. Currently, industrial P4 production is gated by the infrastructurally demanding reduction of phosphate rock by carbon coke in an arc furnace at temperatures of up to 1500 °C. The electrochemical reduction of phosphate salts could enable the sustainable, point-of-use manufacture of white phosphorus; however, such P4 electrosynthesis requires the rapid activation of strong P—O bonds. Herein, we show that the intrinsic oxide-accepting character of phosphoryl anhydride linkages in molten condensed phosphate salts promotes the reduction of phosphate to white phosphorus at high electron and energy efficiencies. These findings could enable an efficient, low-carbon alternative to legacy carbothermal synthesis of P4.