Reutilizing Methane Reforming Spent Catalysts as Efficient Overall Water-Splitting Electrocatalysts

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Designing efficient and stable bifunctional electrocatalysts for electrochemical water splitting is crucial but challenging.
• Spent catalysts deactivated by carbon deposition represent a significant waste stream, posing environmental concerns.
• Reutilizing deactivated catalysts offers a sustainable approach to developing new catalytic materials.

Purpose of the Study:

• To develop a greener bifunctional electrocatalyst by repurposing spent methane reforming catalysts.
• To investigate the electrocatalytic activity and stability of MoS2 deposited on graphitic carbon (GC) and carbon nanofibers (CNF).
• To explore the synergistic effects between MoS2 and carbon supports for enhanced water splitting performance.

Main Methods:

• Synthesis of MoS2@GC and MoS2@CNF electrocatalysts via in situ deposition using a hydrothermal method.
• Electrochemical characterization including linear sweep voltammetry (LSV) to evaluate hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance.
• Durability testing of the synthesized catalysts over extended periods and cycling.

Main Results:

• MoS2@CNF and MoS2@GC catalysts exhibited exceptional performance for HER and OER.
• Achieved low overpotentials for OER (128-154 mV at 25 mA cm-2) and HER (186-207 mV at 25 mA cm-2).
• Demonstrated good long-term durability (18 h at 100 μA cm-2) and stability over 1000 HER cycles.

Conclusions:

• The synergistic effect between MoS2 and the carbon support (GC/CNF) significantly enhances electrocatalytic activity for overall water splitting.
• Repurposing spent catalysts with minimal MoS2 is a viable strategy for engineering potent and greener electrocatalysts.
• This approach offers a sustainable and cost-effective route for producing advanced catalysts for clean energy applications.