Electrocatalytic Oxygen Reduction Reaction Using a Water-Stable Ni-Based Coordination Polymer with Two-Dimensional...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Metal-organic coordination polymers (MOCPs) are advanced materials with tunable structures and properties.
• Electrocatalysis, particularly the oxygen reduction reaction (ORR), is critical for energy conversion technologies like fuel cells.
• Developing efficient and stable electrocatalysts is a key challenge in sustainable energy research.

Purpose of the Study:

• To synthesize and characterize a new Ni(III)-based MOCP.
• To investigate the electrocatalytic performance of the synthesized MOCP for the oxygen reduction reaction (ORR).
• To elucidate the mechanism and factors contributing to the observed electrocatalytic activity and stability.

Main Methods:

• Synthesis of the Ni(III)-based MOCP using the slow layer diffusion method.
• Structural characterization via single-crystal X-ray diffraction (SCXRD) and powder X-ray diffraction.
• Electrochemical evaluation of ORR activity in alkaline media, including cyclic voltammetry and rotating disk electrode techniques.
• Spectroscopic and analytical techniques (FTIR, TGA, UV-vis, luminescence, BET, XPS) for comprehensive material analysis.
• Density functional theory (DFT) calculations to understand the reaction mechanism.

Main Results:

• A new Ni(III)-based MOCP, [Ni(4,4'-IPDPA)_1.5(H₂O)₃]·6H₂O (compound 1), was successfully synthesized and characterized.
• Compound 1 exhibited remarkable electrocatalytic activity for the ORR with a nearly four-electron mechanism and a half-wave potential of 0.72 V vs RHE.
• The MOCP demonstrated excellent long-term stability and exceptional resistance to methanol poisoning during ORR.
• DFT analysis indicated a four-electron pathway with *O intermediate formation as the potential-determining step.

Conclusions:

• The synthesized Ni(III)-based MOCP is a highly efficient and stable electrocatalyst for the oxygen reduction reaction.
• The material's porous structure and the Ni(III)/Ni(II) redox couple contribute to its superior ORR performance.
• This MOCP holds significant potential for applications in alkaline fuel cells and other electrochemical energy devices.