Triggering Redox Active Sites Through Electronic Structure Modulation in rGO Encapsulated Mixed Transition Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient noble-metal-free catalysts is crucial for clean hydrogen generation via water splitting.
• Carbonaceous materials serve as effective templates for electrocatalyst synthesis.
• Understanding the electrochemical performance of novel catalyst structures is essential.

Purpose of the Study:

• To investigate the catalytic performance of rGO-encapsulated Mn and V mixed oxide hybrid structures (MVG) on a NiFeP matrix for hydrogen evolution reaction (HER) in alkaline environments.
• To explore a facile synthesis route for hierarchical MVG hollow microspheres and their integration onto a NiFeP matrix.
• To elucidate the synergistic effects and electronic properties contributing to enhanced HER activity.

Main Methods:

• One-step in situ solvothermal synthesis of hierarchical MVG hollow microspheres.
• Facile electroless plating technique to develop MVG/NiFeP coatings.
• X-ray photoelectron spectroscopy (XPS) for surface and electronic structure analysis.
• Electrochemical characterization including overpotential, Tafel slope, and charge transfer resistance (Rct) measurements.

Main Results:

• The synthesized MVG/NiFeP coatings exhibit hierarchical hollow microsphere structures.
• XPS analysis revealed redox active sites in Mn and V, with rGO facilitating electronic conduction.
• The hybrid structure demonstrated a lower overpotential of 85 mV at 10 mA cm⁻², a reduced Tafel slope of 64.1 mV dec⁻¹, and a lower Rct (545.3 Ω).
• A Volmer-Heyrovsky mechanism was identified for the hydrogen evolution reaction.

Conclusions:

• The rGO-encapsulated Mn and V mixed oxide hybrid structures on a NiFeP matrix are effective noble-metal-free catalysts for HER.
• Synergistic effects between NiFeP and MVG, coupled with modulated electronic structures, enhance electron transfer kinetics.
• The developed catalyst offers a promising pathway for efficient and cost-effective clean hydrogen production in alkaline media.