High-Dimensional MoO_x Promotes Meta-Stable Mo⁵⁺ Active Site Regeneration for Efficient H₂O₂ Electrosynthesis.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The two-electron oxygen reduction reaction (2e^- ORR) is a promising green route for hydrogen peroxide (H₂O₂) production.
• Current challenges include low catalyst selectivity, active site degradation, and insufficient productivity.

Purpose of the Study:

• To develop a novel catalyst for efficient and stable 2e^- ORR.
• To investigate the structure-activity relationship in molybdenum oxide catalysts for H₂O₂ synthesis.

Main Methods:

• Synthesis of high-dimensional rod-like molybdenum oxide (HDS-MoO_x) with a non-traditional phase.
• Electrocatalytic performance evaluation of HDS-MoO_x for 2e^- ORR.
• Mechanistic studies using electrochemical techniques to understand active site behavior and reaction pathways.

Main Results:

• HDS-MoO_x exhibited significantly improved ORR performance compared to conventional α-MoO₃.
• Achieved 97% H₂O₂ Faraday efficiency and a high average yield of 875 mmol g_cat^-1 h^-1.
• Demonstrated abundant meta-stable Mo⁵⁺ active sites and reversible Mo⁵⁺/Mo⁶⁺ valence cycling for enhanced stability.

Conclusions:

• The unique high-dimensional architecture of HDS-MoO_x is crucial for efficient O₂ activation and H₂O₂ production.
• Reversible valence cycling effectively prevents active site depletion, ensuring long-term catalytic stability.
• This study presents a novel strategy for designing high-performance 2e^- ORR catalysts for sustainable H₂O₂ synthesis.