Hydrogen Production at a NiO Photocathode Based on a Ruthenium Dye-Cobalt Diimine Dioxime Catalyst Assembly: Insights...

Area of Science:

• Bioinspired chemistry and artificial photosynthesis
• Photoelectrochemical water splitting
• Sustainable energy conversion

Background:

• Efficient hydrogen production is crucial for the ecological transition.
• Photoelectrochemical water splitting offers a sustainable route to hydrogen.
• Dye-sensitized photocathodes with integrated catalysts are promising for this application.

Purpose of the Study:

• To design and characterize a NiO photocathode sensitized with a ruthenium-cobalt dyad for hydrogen production.
• To investigate the performance and stability of the molecular photocathode system.
• To identify limitations for rational design of future solar fuel devices.

Main Methods:

• Preparation of a NiO photocathode sensitized with a phosphonate-derivatized ruthenium tris-diimine photosensitizer covalently linked to a cobalt diimine dioxime catalyst.
• Photoelectrochemical characterization under simulated AM 1.5G irradiation.
• Advanced spectroscopy and surface characterization techniques.

Main Results:

• Achieved photocurrent densities of 84 ± 7 μA·cm⁻² for hydrogen production.
• Identified fast dyad desorption from the NiO electrode as a performance limitation.
• Observed low electron transfer yield and cobalt demetallation, impacting system stability.

Conclusions:

• The developed dye-sensitized photocathode demonstrates high photocurrent densities for solar hydrogen production.
• Dyad stability and efficient electron transfer are key challenges for improving performance.
• This work provides insights for the rational design of molecular photocathodes for sustainable solar fuel generation.