Polymeric Hydrogel Interphase Enables Transport-Compatible Fe Stabilization for Hectowatt-Scale Alkaline Water...

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Durable oxygen evolution reaction (OER) in industrial alkaline water electrolysis (AWE) is challenging due to iron dissolution in NiFe layered double hydroxides (LDH).
• Sluggish ion transport and bubble release at the gas-liquid-solid interface further impede OER performance.

Purpose of the Study:

• To design a novel interphase for stabilizing Fe sites and enhancing interfacial transport in NiFe LDH for improved OER durability.
• To investigate the mechanism of Fe stabilization and multiphase transport facilitated by the interphase in AWE.

Main Methods:

• Coating NiFe LDH with an ultrathin sodium polyacrylate (PANa) hydrogel layer.
• Characterization of the PANa interphase's effect on Fe site stability and interfacial transport.
• Testing the performance of the modified anode in a hectowatt-scale AWE system.

Main Results:

• The PANa interphase enabled a self-regulated Fe dissolution-redeposition process, stabilizing active sites.
• Enhanced hydroxyl ion (OH-) transport and rapid oxygen gas (O2) disengagement were observed.
• The PANa/NiFe LDH anode demonstrated stable operation for over 2500 h at 0.5 A cm-2 in a 600 W AWE system.

Conclusions:

• The PANa hydrogel interphase effectively boosts OER durability and efficiency in industrial AWE.
• This approach offers a promising strategy for cost-effective hydrogen production with low energy consumption (4.25 kWh Nm-3 H2).
• The projected hydrogen production cost is competitive at US$ 2.38 kgH2-1.