Hydrogen Production Using a Nickel Catalyst Combining Redox Activity and Pendent Base Effects.
Scott A Wicker1, Phillips Hutchison1, Robert G Musicante1
1Department of Chemistry, Rhodes College, 2000 N. Parkway, Memphis, Tennessee 38112, United States.
Inorganic Chemistry
|December 19, 2023
Summary
Researchers developed novel nickel catalysts for efficient hydrogen production using earth-abundant elements. The most active catalyst, featuring pendent pyridines, demonstrated significant electrochemical proton reduction and high turnover numbers in a light-driven system.
Area of Science:
- Catalysis
- Renewable Energy
- Organometallic Chemistry
Background:
- Growing demand for clean energy drives research into sustainable hydrogen production.
- Earth-abundant elements are preferred for developing cost-effective catalysts.
- Pyridinediimine ligands offer potential for catalytic applications due to their coordinating abilities.
Purpose of the Study:
- Synthesize and characterize novel nickel complexes with pyridinediimine ligands.
- Evaluate the catalytic activity of these complexes for hydrogen production.
- Investigate the role of pendent nitrogen moieties in enhancing catalysis.
Main Methods:
- Synthesis of two nickel complexes with pyridinediimine ligands.
- Electrochemical characterization, including cyclic voltammetry.
- Density functional theory (DFT) calculations.
- Assessment in a light-driven catalytic system with Ru(bpy)3^2+ and ascorbic acid.
Main Results:
- The nickel complex with pendent pyridines exhibited the highest catalytic activity.
- Electrochemical proton reduction was achieved with an overpotential of 490 mV.
- DFT calculations supported a proposed mechanism involving protonation of a dissociated pyridine.
- A turnover number (TON) of 1400 was obtained in the light-driven system.
Conclusions:
- Nickel complexes with pyridinediimine ligands are effective catalysts for hydrogen production.
- Pendent pyridine groups enhance catalytic activity through a proposed protonation mechanism.
- These findings contribute to the development of sustainable catalysts for renewable energy applications.
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