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 sp 2 hybrid orbitals to form CH4 gas. Therefore, only carbon with sp 3 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.