Nickel(II) Porphyrin Complex-Derived Electrocatalysts for Oxygen Evolution.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The oxygen evolution reaction (OER) is crucial for electrocatalytic water splitting but is limited by sluggish kinetics and high overpotentials.
• Nickel tetraphenylporphyrin (NiTPP) shows promise as an OER catalyst, but its intrinsic performance is often insufficient for practical applications.

Purpose of the Study:

• To develop a highly active and durable OER catalyst by strategically carbonizing NiTPP.
• To investigate the effect of controlled carbonization temperature on catalyst performance and stability.

Main Methods:

• Controlled pyrolysis of NiTPP precursor at 400 °C, 600 °C, and 800 °C under a specific atmosphere.
• Electrochemical characterization including overpotential, Tafel slope, and long-term stability tests in 1 M KOH.
• Analysis of the synergistic effects between embedded nickel species and the derived conductive carbon matrix.

Main Results:

• The NiTPP-800 catalyst, carbonized at 800 °C, demonstrated superior OER performance.
• Achieved a low overpotential of 347 mV at 20 mA cm⁻² and a Tafel slope of 86 mV dec⁻¹.
• Exhibited excellent long-term stability, maintaining performance over 1000 CV cycles.

Conclusions:

• Controlled carbonization effectively embeds active nickel species within a conductive carbon matrix, enhancing charge transport and active site exposure.
• The NiTPP-800 catalyst offers a promising solution for efficient and durable electrocatalytic water splitting.
• This approach highlights the potential of porphyrin-derived carbon materials for advanced catalytic applications.