Partial deligandation activated ZIF-67 for efficient electrocatalytic oxygen reduction reaction

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) possess advantageous multi-active sites and mass transfer properties.
• Unlocking these intrinsic properties is key to enhancing their performance in electrocatalysis, particularly for the oxygen reduction reaction (ORR).
• Blocked molecular groups in MOFs often hinder their full catalytic potential.

Purpose of the Study:

• To develop an effective method for activating the electrocatalytic sites of MOFs.
• To investigate the impact of low-temperature pyrolysis on MOF structure and ORR performance.
• To create a MOF-based electrocatalyst comparable to commercial platinum catalysts for the oxygen reduction reaction.

Main Methods:

• Partial diligandation-activated ZIF-67 (ZIF-67-400) was synthesized via simple low-temperature pyrolysis.
• The material's structural integrity, morphology, and crystal structure were analyzed post-pyrolysis.
• Electrocatalytic activity and stability for the oxygen reduction reaction (ORR) were evaluated.

Main Results:

• ZIF-67-400 maintained its dodecahedron morphology and crystal structure after pyrolysis.
• Hydrocarbon groups were eliminated, exposing active sites and enhancing porosity.
• The activated ZIF-67-400 demonstrated excellent ORR activity (0.82 V half-wave potential) and stability (96% after 10 hours), rivaling commercial Pt/C.

Conclusions:

• Low-temperature annealing is an effective strategy for activating MOFs for electrocatalysis.
• The partial diligandation process successfully exposed intrinsic active sites in ZIF-67.
• This approach offers a viable alternative pathway for enhancing MOF electrocatalytic performance in fuel cells.