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Updated: May 8, 2026
10:21
Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions
Published on: October 5, 2019
Synthesis, structural characterization, and electrocatalytic hydrogen generation activity of
Anjali Mishra1, Chote Lal Yadav1,2, Jun Yi3
1Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India. nsingh@bhu.ac.in.
Dalton Transactions (Cambridge, England : 2003)
|May 7, 2026
Summary
Four new cobalt complexes were synthesized and tested for electrocatalytic hydrogen evolution. Complex 1 showed superior activity, indicating potential for efficient proton reduction catalysis.
Area of Science:
- Inorganic Chemistry
- Materials Science
- Electrochemistry
Background:
- Cobalt complexes are increasingly explored for electrocatalytic applications, particularly in energy conversion.
- Developing efficient catalysts for proton reduction is crucial for sustainable hydrogen production.
- Homoleptic facial-octahedral cobalt(III) β-oxodithioester complexes offer a promising structural motif.
Purpose of the Study:
- To synthesize and characterize novel cobalt(III) β-oxodithioester complexes.
- To evaluate their electrocatalytic activity for proton reduction.
- To elucidate the mechanism of electrocatalytic hydrogen evolution.
Main Methods:
- Synthesis and full characterization of four homoleptic cobalt(III) complexes using elemental analysis, FTIR, UV-Vis, and NMR spectroscopy.
- Single-crystal X-ray diffraction to determine molecular structure and coordination geometry.
- Electrochemical studies in dimethylformamide (DMF) with trifluoroacetic acid (TFA) for proton reduction evaluation, including cyclic voltammetry, controlled potential electrolysis (CPE), and foot-of-the-wave analysis (FOWA).
- Spectroelectrochemical studies and computational analysis to support mechanistic investigations.
Main Results:
- Four [Co(L)3] complexes (L = β-oxodithioester ligands) were successfully synthesized and characterized, exhibiting distorted octahedral geometry with O^S-chelation.
- All complexes demonstrated electrocatalytic hydrogen evolution activity in acidic media.
- Complex 1 exhibited superior performance with an overpotential of 580 mV, high turnover frequencies (~10^3 s^-1), and 89% faradaic efficiency.
- Complexes showed good stability under acidic conditions during catalysis.
- Mechanistic studies supported an ECEC mechanism with the second protonation step being rate-determining.
Conclusions:
- The synthesized cobalt(III) β-oxodithioester complexes are effective electrocatalysts for proton reduction.
- Complex 1 represents a highly active and stable catalyst for hydrogen evolution.
- The ECEC mechanism, with the second protonation as the rate-determining step, governs the catalytic process.
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