Generation of Elemental Fluorine through the Electrolysis of Copper Difluoride at Room Temperature

Abstract

The safe generation of F2 gas at room temperature by using simple cell configurations has been the “holy grail” of fluorine research for centuries. Thus, to address this issue, we report generation of F2 gas through the electrolysis of CuF2 in a CsF‐2.45HF molten salt without the evolution of H2 gas. The CuF2 is selected through a series of thermodynamic and kinetic assessments of possible metal fluorides. Anode assessments on graphite and glass‐like carbon demonstrate the effect of the absence of the anode during generation of F2 gas owing to stabilized operations at room temperature. Although the Ni anode dissolves during electrolysis in the conventional medium‐temperature cell, herein, it facilitates stable electrolysis over 100 h, achieving an F2 gas purity of over 99 % with the potential to operate using one‐compartment electrolysis. This work presents a safe and propitious method for the generation of high‐purity F2 gas for small‐scale lab and industrial applications.

Anode electrolysis of sulfides

“…Note that the Cu 2 S-to-Cu + -and-sulfur conversion is thermodynamically more favorable than that of Cu 2 S-to-Cu 2+ -and-sulfur and CuCl-to-CuCl 2 conversions. On the cathode side, the deposition potential of Cu is much more positive than that of Li, Na, and K, which has been widely verified ( 42 – 45 ). Hence, the competition reactions at both anode and cathode are negligible in molten salt, which is markedly different from the deposition in the aqueous solution that must compete with the H 2 evolution reaction ( 46 ).…”

Preface for the 66th Special Feature “Novel Aspects and Approaches to Experimental Methods for Electrochemistry”

“…His research interests are in inorganic fluorine chemistry and electrochemistry including structural characterization of new chemical species, synthesis and application of ionic liquids, and evaluation of electrolyte and electrode materials for electrochemical devices and processes. [10][11][12][13][14][15][16][17] [18][19][20][21] He also investigated physicochemical properties of electrolytes for sodiumion based devices and assembled sodium-ion capacitor. [22][23][24][25] Recently, He focuses on sulfide-base all solid-state batteries.…”