title: Synthetically Tuned Atomic Ordering in PdCu Nanoparticles with Enhanced Catalytic Activity toward Solvent-Free Benzylamine Oxidation.
abstract: Synthesis of ordered compounds with nano size is of particular interest for tuning the surface properties with enhanced activity and selectivity toward various important industrial catalytic processes. In this work, we synthesized ordered PdCu nanoparticles as highly efficient catalyst for the solvent-free aerobic oxidation of benzylamine. The PdxCu1-xcatalysts with different chemical compositions (x = 0, 0.25, 0.4, 0.5, 0.6, 0.75, 1) were prepared by polyol method using NaBH4as a reducing agent and were well-characterized by X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) energy-dispersive analysis of X-rays, and X-ray absorption fine structure. The effect of different metal concentrations of Pd and Cu on the formation of PdxCu1-xnanoparticles was investigated. The XRD and TEM confirmed the formation of ordered PdCu intermetallic phase with body-centered cubic (BCC) structure for the synthetic composition of Pd/Cu = 1:1. For compositions x = 0, 0.25, 0.75, and 1, PdxCu1-xalloy with face-centered cubic (FCC) structure was observed, whereas mixed phase of BCC and FCC was observed for x = 0.4 and 0.6. The use of strong reducing agent (NaBH4) was essential to synthesize PdCu ordered phase compared to weak reducing agents such as oleylamine and ascorbic acid. The PdCu nanocatalyst with ordered structure (BCC) showed excellent catalytic activity compared to PdxCu1-xalloy nanoparticles with FCC structure. The atomic ordering in the PdCu intermetallic was the driving force for the enhancement in the catalytic activity with high benzylamine conversion of 94.0% and dibenzylimine selectivity of 92.2% compared to its monometallic and alloy counterparts. Moreover, ordered PdCu alloy showed good recyclability and activity toward the oxidation of different amines.
authors.affiliation: New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.
authors.forename: Vijaykumar S
authors.initials: VS
authors.lastname: Marakatti
authors.affiliation: New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.
authors.forename: Saurav Ch
authors.initials: SC
authors.lastname: Sarma
authors.affiliation: Elettra Sincrotrone Trieste SCpA , SS14 Km 163.5, Trieste, Basovizza 34149, Italy.
authors.forename: Boby
authors.identifier: http://orcid.org/0000-0002-3334-7540
authors.initials: B
authors.lastname: Joseph
authors.affiliation: Dutch-Belgian Beamline, The European Synchrotron Radiation Facility , CS 40220, 38043 Grenoble, France.
authors.forename: Dipanjan
authors.identifier: http://orcid.org/0000-0002-1933-8066
authors.initials: D
authors.lastname: Banerjee
authors.affiliation: New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.
authors.forename: Sebastian C
authors.identifier: http://orcid.org/0000-0002-5211-446X
authors.initials: SC
authors.lastname: Peter
keywords: PdCu; alloy; benzylamine; catalysis; intermetallics; nanoparticles; ordered structures; oxidation