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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. [Display omitted] • Core/shell-structured Ru-Ti-Nb mixed oxides exhibit superior durability at high current densities. • Liquid-diffusion electrode enables near-zero polarization for CER regardless of current density. • Exceptionally high HER activity in chlor-alkali condition with an overpotential of 11 mV at 10 mA cm−2. • Chlor-alkali electrolyzer using RNTO/Ti foams as anode and cathode exhibits 1.84 V cell voltage at 100 mA cm−2. [ABSTRACT FROM AUTHOR]

To reduce the use of noble metals, iridium oxide (IrO 2 ) catalysts are prepared on carbon paper (CP) by electrodeposition for use as the anodes in polymer electrolyte membrane water electrolysis (PEMWE). The activities of the fabricated electrodes toward the oxygen evolution reaction are evaluated. The loading amount and morphology of the IrO 2 deposits are varied by controlling the electrodeposition potential ( E dep ) and time ( t dep ). When electrodeposited at 0.7 V, the IrO 2 loading ranges from 0.007 to 0.464 mg cm −2 ( t dep : 1 ∼ 30 min). In the PEMWE test at 90 °C, the IrO 2 /CP electrode with an IrO 2 loading of 0.1 mg cm −2 shows the highest performance (1.92 A cm −2 at 1.8 V) in which high IrO 2 utilization is achieved without significant exposure of the substrate carbon surface. The developed IrO 2 /CP electrodes provide cell performances comparable to those in previous reports with a higher IrO 2 loading, indicating markedly enhanced mass activity. [ABSTRACT FROM AUTHOR]