Pristine S,N-containing Mn-based metal organic framework nanorods enable efficient oxygen reduction electrocatalysis

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) possess unique physicochemical properties suitable for electrocatalysis.
• Direct application of pristine MOFs as electrocatalysts remains challenging, with many studies using them as precursors.
• Developing efficient, direct MOF-based electrocatalysts is crucial for energy conversion applications.

Purpose of the Study:

• To synthesize S,N-containing manganese MOFs (Mn-MOFs) with controlled morphologies for direct electrocatalysis.
• To investigate the influence of synthesis parameters (reaction time, anions) on Mn-MOF properties and oxygen reduction reaction (ORR) activity.
• To evaluate the electrocatalytic performance of the optimized Mn-MOFs against commercial platinum/carbon (Pt/C).

Main Methods:

• Hydrothermal synthesis using MnII, thiophene-2,5-dicarboxylate (Tdc), and 4,4'-bipyridine (4,4'-Bpy).
• Systematic variation of reaction times (0, 2, 4 h) and anions (SO42-, Cl-, NO3-, CH3COO-).
• Electrochemical characterization of synthesized Mn-MOFs for ORR activity, stability, and selectivity.

Main Results:

• Uniform one-dimensional (1D) MnII[(Tdc)(4,4'-Bpy)]n nanorods were formed under specific conditions (MnSO4, 4 h reaction time).
• These 1D nanorods demonstrated high ORR activity (onset potential 0.98 V, half-wave potential 0.78 V vs. RHE), comparable to Pt/C.
• The Mn-MOF nanorods exhibited superior stability, methanol resistance, and ORR selectivity compared to Pt/C.

Conclusions:

• Optimized hydrothermal synthesis yields highly efficient 1D Mn-MOF nanorods for direct electrocatalysis.
• The 1D nanostructure facilitates electron/mass transport, enhancing ORR performance.
• This study presents a viable strategy for fabricating advanced MOF-based catalysts for energy storage and conversion.