Copper complexes as catalyst precursors in the electrochemical hydrogen evolution reaction

Area of Science:

• Coordination Chemistry
• Electrochemistry
• Catalysis

Background:

• Copper complexes are investigated for catalytic applications.
• Understanding ligand effects on metal ion speciation is crucial.
• Electrochemical proton reduction is a key area in sustainable energy.

Purpose of the Study:

• Synthesize and characterize copper(II) complexes with novel ligand scaffolds.
• Evaluate their performance in electrochemical hydrogen evolution reaction (HER).
• Investigate the role of ligands and complex speciation in catalysis.

Main Methods:

• Synthesis of copper(II) complexes with two distinct ligand types.
• pH-dependent speciation studies (mononuclear/dinuclear equilibrium).
• Electrochemical testing for hydrogen evolution reaction (HER) in aqueous media.

Main Results:

• Two water-soluble copper(II) complexes with N4-coordination environments were synthesized.
• Complex solutions exhibited high catalytic activity for HER in acidic water.
• Complex decomposition under catalytic conditions led to active copper(0) and Cu2O deposits.

Conclusions:

• The active HER catalysts are copper deposits formed in situ, not the intact complexes.
• Ligand presence or absence did not affect the catalytic activity of the solution or deposit.
• Insights into the stability and decomposition pathways of copper catalysts in aqueous HER were gained.