Electrochemical Synthesis of Diamond in Molten LiCl-KCl-K₂CO₃-KOH

Abstract

We propose a novel diamond synthesis method based on molten salt electrolysis. In our method, carbon deposition and hydrogen generation occur simultaneously, and hydrogen reacts selectively with carbon atoms that possess sp² hybrid orbitals to form CH₄ gas. Therefore, only carbon with sp³ hybrid orbitals grows to form a diamond. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy analysis confirmed that diamond was synthesized by potentiostatic electrolysis at 1.1 V vs Li⁺/Li with a 10 C cm⁻² charge density in molten LiCl–KCl–K₂CO₃–KOH at 973 K.