Efficient Decoupled Electrolytic Water Splitting in Acid through Pseudocapacitive TiO₂

Area of Science:

• Electrochemistry
• Materials Science
• Green Energy Technologies

Background:

• Water electrolysis is crucial for green energy but current membrane electrolyzers require high temperatures and alkaline conditions, limiting applications.
• Existing technologies face challenges in broad adoption due to operational constraints.

Purpose of the Study:

• To introduce and demonstrate a novel decoupled electrolysis process for water splitting under mild acidic conditions.
• To evaluate the efficiency and stability of this new method using cost-effective materials.

Main Methods:

• Developed ultra-small anatase titanium dioxide (TiO2) nanoparticles (4.5 nm) supported on carbon felt electrodes.
• Implemented a decoupled electrolysis strategy sequentially performing oxygen evolution (OER) and hydrogen evolution (HER) at the same catalyst.
• Utilized pseudocapacitive charge storage of H+ ions generated during OER to drive HER.

Main Results:

• Achieved a high electrochemical surface area and capacitance (375 F g-1) with the TiO2 electrodes.
• Demonstrated decoupled water splitting with an overall energy efficiency of 52.4%.
• Exhibited excellent stability over 3000 cycles of testing.

Conclusions:

• Decoupled electrolysis using TiO2 in mild acidic conditions offers a viable alternative to traditional membrane electrolyzers.
• This approach eliminates the need for harsh alkaline electrolytes and elevated temperatures, broadening the scope of water electrolysis applications.
• The use of abundant and inexpensive TiO2 presents a scalable and sustainable solution for green hydrogen production.