Dual-functional phosphomolybdic acid-polypyrrole-ionic liquid nanocomposites for energy storage and hydrogen...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology
• Catalysis

Background:

• Nanostructured materials are crucial for advanced energy storage and catalysis.
• Polypyrrole (PPy) is a promising pseudocapacitive material.
• Modification of PPy with polyoxometalates and ionic liquids can enhance its properties.

Purpose of the Study:

• To investigate the modification of polypyrrole (PPy) surfaces with polyoxometalate (PVMo11) and ionic liquids (BMI).
• To evaluate the electrochemical energy storage and electrocatalytic hydrogen evolution reaction (HER) performance of the synthesized nanocomposites.
• To understand the underlying mechanisms through density functional theory (DFT) calculations.

Main Methods:

• Synthesis of polypyrrole (PPy) modified with polyoxometalate H4[PVMo11O40].xH2O (PVMo11) and 1-benzyl-3-methylimidazolium chloride (BMI).
• Electrochemical characterization including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy.
• Electrocatalytic activity testing for hydrogen evolution reaction (HER) and density functional theory (DFT) calculations.

Main Results:

• The PVMo11-BMI-PPy nanocomposite exhibited a specific capacitance of 400 F g-1, energy density of 49.5 Wh kg-1, and power density of 906 W kg-1.
• It demonstrated excellent cyclic stability (91.1% retention after 10,000 cycles) and coulombic efficiency (98.9%).
• PVMo11-BMI-PPy showed superior HER activity (19 mV overpotential at 10 mA cm-2), outperforming Pt, with a high TOF of 6.91 × 10-7 s-1 and excellent long-term stability.

Conclusions:

• The PVMo11-BMI-PPy nanocomposite is a highly effective material for both energy storage and HER catalysis.
• DFT studies confirmed that the V site in PVMo11-BMI-PPy provides an optimal catalytic environment for HER.
• This bifunctional material holds significant promise for next-generation energy applications.