Kristallstruktur von Pd5Bi2

Pulsed Electrodeposition of Metastable Pd31Bi12 Nanoparticles for Oxygen Reduction Electrocatalysis

“…To identify the crystal structure of the as-deposited sample, powder X-ray diffraction (XRD) patterns were obtained by scratching off the film onto double-sided kapton tape (Figure a). The primary peaks obtained in the diffractogram match the simulated Pd 31 Bi 12 pattern, indicating that phase-pure Pd 31 Bi 12 was formed . The primary reflections of the deposited Pd 31 Bi 12 are broad; Scherrer analysis of the (1 1 15) reflection indicates that the average grain size of the Pd 31 Bi 12 is ∼15 nm (Figure b).…”

“…To overcome this shortcoming, we herein describe a method utilizing pulsed electrochemical deposition to decouple nucleation from growth kinetics, allowing for the direct synthesis of sub-15 nm diameter metastable ordered intermetallic Pd 31 Bi 12 nanoparticles that uniformly decorate commercial carbon black supports. Thermodynamic phase diagrams indicated that Pd 31 Bi 12 is stable above 500 °C; remarkably, we are able to access this material under conditions in which it is not predicted to be thermodynamically stable . Pulsed electrochemical deposition allows us to access a nonequilibrium synthetic environment, promoting the synthesis of metastable ordered intermetallic nanoparticles .…”

“…The primary peaks obtained in the diffractogram match the simulated Pd 31 Bi 12 pattern, indicating that phase-pure Pd 31 Bi 12 was formed. 37 The primary reflections of the deposited Pd 31 Bi 12 are broad; Scherrer analysis of the (1 1 15) reflection indicates that the average grain size of the Pd 31 Bi 12 is ∼15 nm (Figure 2b). Images collected by transmission electron microscopy (TEM) indicated that Pd 31 Bi 12 was dispersed uniformly on carbon with an average particle size of ∼13 nm, which agrees with the value estimated by the Scherrer analysis (Figure 2b Remarkably, we can access nanoparticles of this material at room temperature in minutes, while the preparation of metastable stable phases by other methods is not straightforward.…”

“…Thermodynamic phase diagrams indicated that Pd 31 Bi 12 is stable above 500 °C; remarkably, we are able to access this material under conditions in which it is not predicted to be thermodynami- cally stable. 37 Pulsed electrochemical deposition allows us to access a nonequilibrium synthetic environment, promoting the synthesis of metastable ordered intermetallic nanoparticles. 36 The resulting Pd 31 Bi 12 nanoparticles achieve a surface area of ∼37 m 2 /g Pd , which is nearly 40× higher than that of conventional electrodeposition processes that yield lowporosity thin film morphologies.…”

Rapid Room-Temperature Synthesis of a Metastable Ordered Intermetallic Electrocatalyst

“…The primary peaks match well with the diffraction pattern of Pd 31 Bi 12 , which can be differentiated from other Pd-rich phases, such as Pd 3 Bi (Figure S2). , Differences in electronegativity and crystal structure between Pd (FCC) and Bi (rhomobohedral) inhibit the formation of solid-solutions as indicated by the Pd–Bi phase diagram; allowing ordered phases to be accessed directly . The phase diagram of Pd–Bi indicates that Pd 31 Bi 12 is thermodynamically stable from 550 to 605 °C.…”