A high-throughput optical screening method for the optimization of colloidal water oxidation catalysts

Area of Science:

• Catalysis
• Materials Science
• Photochemistry

Background:

• Developing efficient and stable water oxidation catalysts is crucial for sustainable energy technologies.
• Colloidal catalysts offer tunable properties and high surface areas for catalytic applications.
• Ruthenium(II) tris(2,2'-bipyridyl) complexes are commonly used as photosensitizers in water oxidation studies.

Purpose of the Study:

• To develop a high-throughput screening method for evaluating colloidal water oxidation catalysts.
• To optimize reaction conditions for iridium oxide colloidal catalysts.
• To synthesize and test doped metal oxide colloids for enhanced water oxidation activity.

Main Methods:

• A 96-well plate format was used for parallel screening of catalysts under visible light irradiation.
• Absorbance measurements at 430 nm monitored the concentration of the photosensitizer, tris(2,2'-bipyridyl)ruthenium(II).
• Factorial design-of-experiment was employed for optimizing reagent concentrations, and parallel microwave synthesis was used for catalyst preparation.

Main Results:

• Optimized conditions (higher colloid concentration, lower Ru(bpy)(3)(2+) concentration, higher pH) doubled catalyst turnovers.
• A good correlation was observed between the high-throughput screening method and direct oxygen evolution measurements.
• Iridium oxide colloids doped with Platinum and Osmium (Ir-Pt-Os) exhibited the highest catalytic activity.

Conclusions:

• The developed high-throughput method is effective for screening and optimizing colloidal water oxidation catalysts.
• Doping iridium oxide with platinum and osmium enhances catalytic performance, likely by reducing particle size.
• This work provides a pathway for accelerated discovery of advanced water oxidation catalysts.