Electrocatalytic hydrogen evolution from neutral water by molecular cobalt tripyridine-diamine complexes

Area of Science:

• Inorganic chemistry
• Electrochemistry
• Catalysis

Background:

• Electrochemical hydrogen production is crucial for renewable energy.
• Developing efficient and stable catalysts for neutral water splitting remains a challenge.
• Cobalt complexes are promising candidates for catalysis due to their tunable electronic properties.

Purpose of the Study:

• To synthesize and characterize a novel cobalt complex with a tripyridine-diamine pentadentate ligand.
• To evaluate the catalytic activity of the cobalt complex for electrochemical hydrogen production in neutral water.
• To assess the long-term stability and performance of the catalyst under operational conditions.

Main Methods:

• Synthesis of a cobalt complex featuring a tripyridine-diamine pentadentate ligand.
• Electrochemical characterization using cyclic voltammetry and chronoamperometry.
• Controlled potential electrolysis (CPE) experiments in a pH 7 phosphate buffer solution.
• Analysis of hydrogen gas production and catalyst stability over time.

Main Results:

• The cobalt complex exhibited high catalytic activity for hydrogen evolution, reaching 860 mol H2 (mol cat)(-1) h(-1) (cm(2) Hg)(-1).
• The catalyst maintained its activity over a 60-hour chronoamperometry experiment at -1.25 V.
• No considerable deactivation of the catalyst was observed during the extended electrolysis, indicating excellent stability.
• The reaction was performed in neutral water (pH 7), highlighting the catalyst's effectiveness under mild conditions.

Conclusions:

• The synthesized cobalt complex is a highly active and stable electrocatalyst for hydrogen production from neutral water.
• The catalyst's performance suggests significant potential for practical applications in sustainable hydrogen generation.
• The stability of the complex under neutral pH conditions is a key advantage for future technological development.