A Self-Templated Design Approach toward Multivariate Metal-Organic Frameworks for Enhanced Oxygen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Multivariate metal-organic frameworks (MOFs) are promising electrocatalysts due to synergistic effects from multiple metal sites.
• Developing efficient electrocatalysts is crucial for energy conversion technologies like water splitting.

Purpose of the Study:

• To design and synthesize novel ternary metal-organic frameworks (MOFs) for improved electrocatalytic activity.
• To investigate the synergistic effects of multiple metal active sites in MOFs for the oxygen evolution reaction (OER).

Main Methods:

• A self-templated strategy was employed to grow cobalt/copper MOFs in situ on nickel MOF surfaces, creating ternary Co-NiMOFs.
• Electrochemical performance, including overpotential and Tafel slope, was evaluated for the oxygen evolution reaction (OER).
• Density functional theory (DFT) calculations were used to analyze the reaction mechanism and synergistic effects.

Main Results:

• Ternary CoCu-NiMOFs exhibited enhanced intrinsic electrocatalytic activity due to electron rearrangement between adjacent metals.
• Optimized ternary Co3Cu-Ni2 MOFs nanosheets achieved a current density of 10 mA cm-2 at a low overpotential of 288 mV with a Tafel slope of 87 mV dec-1 for OER.
• The OER process was found to be favorable at Cu-Co concerted sites with a strong synergistic effect from Ni nodes, supported by low free energy changes.

Conclusions:

• The self-templated synthesis provides a versatile method for creating multivariate MOF electrocatalysts.
• Ternary CoCu-NiMOFs demonstrate superior OER performance compared to bimetallic counterparts, highlighting the potential of synergistic multi-metal active sites.
• These findings offer a pathway towards highly efficient electrocatalysts for energy transduction applications.