The Ir-Pd (Iridium-Palladium) system

IrPd nanoalloys: simulations, from surface segregation to local electronic properties

“…The transition toward disordering shown by the evolution of homoatomic and heteroatomic pairs toward the ratios obtained for full disorder occurs progressively. The latter is reached around 1800 K, in very good agreement with the experimental phase diagram (Tripathi 1991).…”

“…Z and Z tot are the number of first neighbors at the surface and the total number of neighbors of an atom at site i, respectively simulations at increasing temperatures, knowing that the demixing/disorder transition occurs at $ 1800 K (Tripathi 1991) for alloys around equiconcentration. In order to characterize the chemical tendency, we have thus taken the case of the equiconcentrated alloy and plotted (Fig.…”

“…Although the bulk immiscible iridium-palladium has been only scarcely studied till now (Tripathi 1991;Turchi 2006;Kolb 2006), a few experimental reports on this system show its actual interest for catalysis (López-De Jésus et al 2010;Shen et al 2010;Piccolo et al 2012). In particular, it has been shown that supported IrPd nanoalloys are more selective than their pure counterparts in the preferential oxidation of CO in hydrogen excess, a reaction used for the elimination of CO impurities in the H 2 production process (Morfin et al 2012;Zlotea et al 2014).…”

Double enhancement of hydrogen storage capacity of Pd nanoparticles by 20 at% replacement with Ir; systematic control of hydrogen storage in Pd–M nanoparticles (M = Ir, Pt, Au)

“…From our previous work, we expected that the replacement of Pd with Ir would enhance hydrogen-storage capacity because Ir may act as an electron acceptor to Pd as Ir (5d 7 6s 2 ) has two less electrons than Au (5d 10 6s 1 ). However, Pd and Ir do not mix in the bulk state, unlike the Pd–Au system;32 rather, the alloys segregate to form a domain structure 33…”

Supported Ir–Pd nanoalloys: Size–composition correlation and consequences on tetralin hydroconversion properties

“…In the bulk phase, similar to that of Ir-Pt, the phase diagram of Ir-Pd presents a miscibility gap below 1500°C at 50 at.% composition and ranging from ca. 11 to 98 at.% Pd at 500°C [30]. This may increase the difficulty to obtain Ir-Pd nanoalloys with respect to the abovementioned Pd-based ones.…”