A nanometric Rh overlayer on a metal foil surface as a highly efficient three-way catalyst

Area of Science:

• Materials Science
• Chemical Engineering
• Catalysis

Background:

• Automotive three-way catalysts (TWC) are crucial for reducing harmful emissions.
• Conventional TWC catalysts often rely on expensive precious metals like Rhodium.
• Improving catalyst efficiency and reducing Rhodium loading are key research goals.

Purpose of the Study:

• To develop a novel Rhodium catalyst using pulsed arc-plasma deposition.
• To evaluate the catalytic activity of the new Rhodium overlayer for TWC applications.
• To compare the performance against conventional Rhodium-based catalysts.

Main Methods:

• Pulsed arc-plasma (AP) deposition of Rhodium nanoparticles onto Fe-Cr-Al stainless steel foil.
• Characterization of Rhodium nanoparticle size, density, and overlayer formation.
• Testing catalytic activity using a simulated TWC reaction with a honeycomb structure.

Main Results:

• AP deposition produced uniform, 1-3 nm Rhodium nanoparticles, forming a continuous overlayer after 1,000 pulses.
• The Rhodium-coated foil honeycomb demonstrated successful light-off at high space velocity (1.2 × 10^5 h⁻¹).
• Turnover frequency for the NO-CO reaction was approximately 80-fold higher than conventional Rh/ZrO2 catalysts.

Conclusions:

• Foil-supported Rhodium overlayers fabricated by AP deposition offer superior catalytic activity for TWC.
• This method presents a promising alternative for designing efficient automotive catalysts with reduced Rhodium loading.
• The nonporous, low surface area foil catalyst outperforms conventional porous catalysts, highlighting a new design paradigm.