Top-down Surfactant-Free Synthesis of Supported Palladium-Nanostructured Catalysts

Abstract

Nanostructured palladium (Pd) is a universal catalyst that is widely used in applications ranging from catalytic converters of combustion engine cars to hydrogenation catalysts in industrial processes. Standard protocols for synthesizing such nanoparticles (NPs) typically use bottom-up approaches. They utilize special and often expensive physical techniques or wet-chemical methods requiring organic surfactants. These surfactants should often be removed before catalytic applications. In this article, the synthesis of Pd NPs immobilized on carbon support by electrochemical erosion without using any surfactants or toxic materials is reported. The Pd NPs synthesis essentially relies on a Pd bulk pretreatment, which causes material embrittlement and allows the erosion process to evolve more efficiently, producing homogeneously distributed NPs on the support. Moreover, the synthesized catalyst is tested for hydrogen evolution reaction. The activity evaluations identify optimal synthesis parameters related to the erosion procedure. The electrocatalytic properties of the Pd NPs produced with sizes down to 6.4 +/- 2.9 nm are compared with a commercially available Pd/C catalyst. The synthesized catalyst outperforms the commercial catalyst within all properties, like specific surface area, geometric activity, mass activity, specific activity, and durability. A surfactant-free top-down approach, called "electrochemical erosion", allows the fabrication of palladium (Pd) nanoparticles (NPs) supported on Vulcan carbon. Crucially, a Pd wire pretreatment is identified as the essential step to synthesize NPs with sizes below 10 nm. The synthesized Pd/C catalysts are thoroughly analyzed for their structure, morphology, chemical composition, and electrochemical activity toward the hydrogen evolution reactions.image (c) 2024 WILEY-VCH GmbHNanostructured palladium (Pd) is a universal catalyst that is widely used in applications ranging from catalytic converters of combustion engine cars to hydrogenation catalysts in industrial processes. Standard protocols for synthesizing such nanoparticles (NPs) typically use bottom-up approaches. They utilize special and often expensive physical techniques or wet-chemical methods requiring organic surfactants. These surfactants should often be removed before catalytic applications. In this article, the synthesis of Pd NPs immobilized on carbon support by electrochemical erosion without using any surfactants or toxic materials is reported. The Pd NPs synthesis essentially relies on a Pd bulk pretreatment, which causes material embrittlement and allows the erosion process to evolve more efficiently, producing homogeneously distributed NPs on the support. Moreover, the synthesized catalyst is tested for hydrogen evolution reaction. The activity evaluations identify optimal synthesis parameters related to the erosion procedure. The electrocatalytic properties of the Pd NPs produced with sizes down to 6.4 +/- 2.9 nm are compared with a commercially available Pd/C catalyst. The synthesized catalyst outperforms the commercial catalyst within all properties, like specific surface area, geometric activity, mass activity, specific activity, and durability. A surfactant-free top-down approach, called "electrochemical erosion", allows the fabrication of palladium (Pd) nanoparticles (NPs) supported on Vulcan carbon. Crucially, a Pd wire pretreatment is identified as the essential step to synthesize NPs with sizes below 10 nm. The synthesized Pd/C catalysts are thoroughly analyzed for their structure, morphology, chemical composition, and electrochemical activity toward the hydrogen evolution reactions.image (c) 2024 WILEY-VCH GmbH