Ni(II)-Pyrazolate Framework Bearing a Metalated Schiff-Base Moiety for Electrocatalytic Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Metal-organic frameworks (MOFs) offer tunable structures for catalytic applications.
• Developing efficient electrocatalysts for hydrogen evolution reaction (HER) is crucial for clean energy technologies.
• Post-synthetic modification (PSM) allows for the introduction of secondary active sites in MOFs.

Purpose of the Study:

• To synthesize a robust and porous Ni-based MOF (NiL1) and functionalize it for enhanced electrocatalysis.
• To investigate the electrocatalytic hydrogen evolution reaction (HER) performance of the modified MOF.
• To explore the role of secondary active sites in improving MOF-based electrocatalyst efficiency.

Main Methods:

• Assembly of a Ni-based MOF (NiL1) using Ni(II) ions and a dipyrazolate linker (L1^2-).
• Post-synthetic modification (PSM) of NiL1 with salicylaldehyde, followed by Ni(II) chelation to form Ni@NiL1-Sal.
• Electrocatalytic testing of Ni@NiL1-Sal with carbon black for hydrogen evolution reaction (HER) performance evaluation.

Main Results:

• The Ni@NiL1-Sal catalyst exhibited enhanced HER performance compared to the primitive NiL1 and NiL1-Sal.
• The optimized catalyst showed the smallest overpotential (384 mV) and Tafel slope (87 mV dec^-1).
• The improved HER performance was attributed to the successful creation of unambiguous secondary active sites.

Conclusions:

• The Ni@NiL1-Sal MOF catalyst demonstrates significant potential for efficient electrocatalytic hydrogen production.
• The strategy of introducing secondary active sites via PSM is effective for designing advanced MOF electrocatalysts.
• This work provides a pathway for rational design of functional MOF-based electrocatalysts for energy applications.