NiFe₂O₄-Triggered Hydrogen Spillover Pathway over NiFe-Layered Double Hydroxide (LDH) for Robust Room-Temperature...

Area of Science:

• Materials Science
• Environmental Chemistry
• Catalysis

Background:

• Active hydrogen (*H)-mediated catalytic decomposition is key for ozone (O3) elimination in humid environments using layered double hydroxides (LDHs).
• Current LDHs struggle with direct water (H2O) activation, limiting surface *H replenishment and causing competitive adsorption effects.
• Efficient ozone decomposition requires catalysts that can effectively activate water and supply active hydrogen.

Purpose of the Study:

• To develop a NiFe2O4-engineered NiFe-LDH catalyst with spatially separated reactive sites for enhanced room-temperature ozone removal in humid conditions.
• To investigate the mechanism of hydrogen generation and spillover in the composite catalyst for improved catalytic activity and durability.
• To provide a novel strategy for ozone purification using hydrogen spillover via engineered catalysts.

Main Methods:

• Synthesis of NiFe2O4/NiFe-LDH composite catalyst.
• Evaluation of catalytic performance for ozone decomposition under varying humidity levels (70% RH) at 25 °C.
• Utilizing experimental techniques and density functional theory (DFT) calculations to elucidate the reaction mechanism.
• Characterization of hydrogen generation and transfer pathways.

Main Results:

• The NiFe2O4/NiFe-LDH composite catalyst achieved 99% ozone decomposition efficiency at 70% relative humidity and 25 °C.
• The reaction rate was 1319 μmol·g-1·h-1, which is 4.6 times higher than that of pure NiFe-LDH.
• DFT calculations confirmed efficient H generation from H2O on NiFe2O4 and subsequent transfer to NiFe-LDH, promoting a cross-interface hydrogen spillover pathway.
• The engineered catalyst demonstrated enhanced durability and weakened competitive adsorption effects.

Conclusions:

• The NiFe2O4-engineered NiFe-LDH catalyst effectively utilizes a hydrogen pump mechanism (NiFe2O4) and catalytic conversion sites (NiFe-LDH) for superior ozone decomposition.
• Spatially separated active sites and the induced hydrogen spillover pathway enable highly efficient and robust ozone removal even under challenging humid conditions.
• This work presents a promising strategy for advanced air purification through engineered catalysts facilitating hydrogen spillover.