Membrane-Free Water Electrolysis for Hydrogen Generation with Low Cost

Area of Science:

• Electrochemistry
• Materials Science
• Green Chemistry

Background:

• Conventional water electrolysis is hindered by expensive membrane-electrode assemblies and inefficient oxygen evolution reactions (OER).
• These limitations increase the cost of green hydrogen (H₂) production compared to conventional methods.
• Safety concerns arise from the potential mixing of hydrogen and oxygen.

Purpose of the Study:

• To develop an innovative and efficient membrane-free water electrolysis system.
• To overcome the cost and safety limitations of conventional water electrolysis.
• To utilize the urea oxidation reaction (UOR) as a more favorable alternative to OER.

Main Methods:

• Development of a novel Cu-based catalyst (Cu_XO) for urea oxidation reaction (UOR).
• Implementation of a membrane-free electrolysis system replacing OER with UOR.
• In situ spectroscopic studies to elucidate the UOR mechanism.
• Techno-economic analysis (TEA) of the membrane-free electrolyzer (MFE).

Main Results:

• The membrane-free electrolysis system achieved the highest H₂ Faradaic efficiency among reported systems.
• The Cu_XO catalyst demonstrated high selectivity for N₂ production and OER inertness via a N₂H_y intermediate.
• The industrial-type MFE reduced electricity consumption to 3.78 kWh Nm^-3, lower than commercial alkaline water electrolyzers (AWE).
• Green H₂ production cost was reduced to US$1.81 kg^-1.

Conclusions:

• The developed membrane-free water electrolysis system offers a cost-effective and safer alternative for green hydrogen production.
• The Cu_XO catalyst and UOR integration are key to achieving high efficiency and low energy consumption.
• This technology meets and exceeds targets for competitive green hydrogen pricing.