Modifying the Substrate-Dependent Pd/Fe₂O₃ Catalyst-Support Synergism with ZnO Atomic Layer Deposition

Area of Science:

• Materials Science
• Nanotechnology
• Catalysis

Background:

• Palladium (Pd) supported on iron oxide (Fe2O3) nanoparticles exhibit synergistic reactivity due to electronic interactions.
• Nanocatalyst systems often face challenges with stability and selectivity.
• Atomic layer deposition (ALD) offers precise control over ultrathin film deposition.

Purpose of the Study:

• To enhance the efficiency of low-loading palladium nanocatalysts.
• To selectively modify the reactivity of supported metal catalysts.
• To demonstrate the use of ultrathin ALD overcoats for catalyst stabilization and tuning.

Main Methods:

• Synthesis of low-loading Pd supported on Fe2O3 nanoparticles.
• Selective overcoating of Fe2O3 with zinc oxide (ZnO) using atomic layer deposition (ALD) with trimethylzinc and water precursors.
• Characterization using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS).
• Evaluation of catalytic performance in various aqueous redox reactions.

Main Results:

• ZnO ALD overcoating selectively dampened hydrogenation reactivity at Fe2O3 sites.
• Catalyst efficiency was enhanced for most aqueous redox reactions due to increased utilization of Pd sites.
• Reactivity toward polyaromatic core substrates was suppressed.
• XPS and UPS indicated minimal electronic effects on Pd, suggesting physical site blocking by ZnO.

Conclusions:

• Ultrathin ALD overcoats can stabilize supported nanocatalysts and selectively alter their reactivity.
• This method provides a facile route to enhance the performance of low-loading Pd-based supported nanocatalysts.
• Site-blocking by ALD coatings offers a strategy for tuning catalyst selectivity.