PtPdRh

PtPdRh refers to a ternary alloy composed of platinum (Pt), palladium (Pd), and rhodium (Rh), used as a catalyst material in a variety of chemical and electrochemical applications. The term encompasses a range of compositions and nanostructures, including nanoparticles, nanowires, and thin films on supports such as carbon, alumina, or ceria. Compositions are chosen to balance activity, selectivity, and stability for a given application.

In automotive catalysis, PtPdRh-based materials are widely employed in three-way catalysts to convert exhaust pollutants. These catalysts aim to simultaneously oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxides, operating effectively under fluctuating temperatures. In electrochemical systems, PtPdRh nanoparticles are investigated as catalysts for the oxygen reduction reaction in fuel cells and for other electrochemical transformations, where alloying can improve activity, resistance to CO poisoning, and durability.

The catalytic performance of PtPdRh arises from synergistic effects among the metals. Pt provides high intrinsic activity, Pd can tune hydrogen-related steps and reduce CO adsorption, and Rh enhances NOx reduction and high-temperature stability. Alloying often improves resistance to sintering and thermal degradation compared with monometallic counterparts. The nanostructure and particle size, as well as the support material, influence surface composition and catalytic behavior, sometimes leading to core–shell or ordered intermetallic architectures with distinct activities.

Challenges include the high cost and scarcity of Pt, Pd, and Rh, as well as sensitivity to sulfur poisoning and aging under real-world conditions. Ongoing research explores optimized compositions, alternative supports, and nanostructures to maximize efficiency while reducing precious metal load. See also: three-way catalyst, bimetallic and trimetallic catalysts, noble metal.