Liquid-diffusion electrode with core-shell structured mixed metal oxide catalyst for near-zero polarization in chlor-alkali electrolysis

Abstract

Chlor-alkali electrolysis is a key industrial process for the production of chlorine gas, caustic soda, and hydrogen fuels. Here, we demonstrate that a Ti foam electrode, which has a diffusion layer of liquid reactant, deposited with a thin layer of core/shell-structured mixed metal oxide nanoparticles enables almost zero polarization in the range of hundreds of mA cm−2 towards the chlorine evolution reaction (CER), using noble-metals 20 times lower than commercial electrode. The fast charge-transfer kinetics induce near-zero overpotential at low current densities, while the high mass transport rates aided by porous channels lead to unprecedentedly high CER performance (LSV derived overpotentials of 9 and 44 mV at 10 and 500 mA cm−2 with Faradaic efficiency of 99.1% and 86.1% in 5.0 M NaCl). Under practical chlor-alkali process conditions, the RNTO/Ti foam exhibited remarkable performance as a bifunctional electrode for CER and hydrogen evolution reaction (HER) with overpotential of 11 mV for HER.