A Promising Silicothermic Route for Low-Temperature, Byproduct-Free Production of White Phosphorus Using Silicon Waste

White phosphorus is a critical material for the medical and electronics industries. Still, its conventional production via carbothermic reduction is plagued by high energy consumption, substantial GHG emissions, and the potential formation of hazardous organophosphorus compounds. Here, we propose a promising alternative approach to white phosphorus production by utilizing silicon sludge, an industrial waste, as a reductant. This novel silicothermic process offers a safer, cleaner, and more energy-efficient route to white phosphorus. Our experiments demonstrate that silicothermic reduction achieves a high volatilization rate of 91.4% at 1273 K, a temperature over 400 K lower than that required for conventional carbon-based methods. Crucially, X-ray Absorption Fine Structure (XAFS) analysis confirmed the selective formation of pure white phosphorus, with no evidence of the P–C bond-containing byproducts observed under carbon-reducing conditions between 873–1273 K. While the present work is based on laboratory-scale experiments, the results highlight the potential of silicon sludge as a sustainable alternative to carbon, transforming an industrial waste into a valuable resource and paving the way for safer and lower-carbon phosphorus manufacturing.