In Situ and Continuous Decoding Hydrogen Generation in Solar Water-Splitting Cells

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Photoelectrochemical (PEC) water splitting is a key technology for sustainable hydrogen production.
• Lack of in situ tools hinders understanding of hydrogen generation mechanisms in PEC systems.

Purpose of the Study:

• To develop and demonstrate a quantitative, spatiotemporally resolved optical sensor for monitoring hydrogen generation and temperature in PEC systems.
• To utilize a fiber Bragg grating (FBG) sensor for in situ, continuous decoding of hydrogen formation.

Main Methods:

• Fabrication of a novel cappuccino cell with BiVO4/TiO2 photoanode and Cu2O/CuO/TiO2 photocathode.
• Deployment of a fiber Bragg grating (FBG) sensor for real-time measurement of hydrogen concentration and temperature.
• In situ and continuous monitoring under varying voltage conditions (biased and unbiased).

Main Results:

• The FBG sensor achieved a temporal resolution of 0.5 seconds for dynamic hydrogen formation detection.
• The sensor demonstrated a low detection limit for hydrogen concentration, as low as 0.6 mM.
• Detailed insights were gained into hydrogen production rates, saturation times, spatial distribution, and electrolyte transfer dynamics.

Conclusions:

• FBG sensors provide a powerful tool for comprehensive in situ monitoring of PEC water-splitting processes.
• This technology advances the understanding and optimization of PEC devices for efficient green hydrogen production.