Independent Multiple-Atom-Site Functionality in Composition Adjustable Immiscible Ru-Rh-Pd-Pt Solid-Solution...

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• High-entropy-alloy (HEA) nanoparticles offer potential for advanced functional materials due to their multi-metallic compositions.
• Investigating the reaction mechanisms of HEAs in heterogeneous catalysis is challenging due to their complex nature.
• Understanding these mechanisms is crucial for optimizing catalytic performance.

Purpose of the Study:

• To synthesize and characterize homogeneously dispersed Ru-Rh-Pd-Pt high-entropy-alloy nanoparticles as multiple-atom-site catalysts (MASC).
• To evaluate the NOx reduction performance of the synthesized MASC.
• To elucidate the reaction mechanism responsible for the enhanced catalytic activity of HEA MASC.

Main Methods:

• Synthesis of homogeneously dispersed Ru-Rh-Pd-Pt HEA nanoparticles with adjustable compositions.
• Performance testing for NOx reduction, including light-off temperature measurements.
• Fourier transform infrared (FTIR) spectroscopy to investigate reaction intermediates and surface species.

Main Results:

• Successfully synthesized Ru-Rh-Pd-Pt HEA MASC with controllable compositions.
• The Ru0.4(Rh0.33Pd0.33Pt0.33)0.6 MASC exhibited significantly higher NOx reduction activity compared to monometallic catalysts, with a ~50°C decrease in light-off temperature.
• FTIR analysis revealed a synergistic mechanism involving CO adsorption, NO adsorption, NO dissociation, and O spillover facilitated by specific metal sites (Ru, Rh, Rh-Pd, Pt).

Conclusions:

• The developed Ru-Rh-Pd-Pt HEA MASC demonstrates exceptional performance in NOx reduction.
• The study provides the first clear elucidation of the heterogeneous catalytic reaction mechanism for HEAs.
• This work highlights the potential of HEAs as highly efficient catalysts by leveraging multi-atom-site synergistic effects.