Reactivity of lithium and platinum at elevated densities

Abstract

Through a series of x-ray diffraction experiments, combined with first-principles calculations, we show that the nobility of platinum can be overcome, reacting with lithium under compression at room temperature. Pressures as low as 2.3 GPa lead to the synthesis of Li 11 Pt 2 , exhibiting the highest lithium content of any known intermetallic compound. Above 16 GPa, Li 11 Pt 2 expels Li and transforms to Li 2 Pt. This change is accompanied by a transformation in bonding characterized by the formation of one-dimensional Pt-Pt bonds with increasingly covalent character at higher densities.

Pressure-Enriched Chemistry of Pt: Prediction and Synthesis of Dense Sodium Platinides

“…Na 2 Pt adopts the MgB 2 -type structure (space group, P6/mmm) throughout the pressure range investigated, analogous to Li 2 Pt. 36,39 It is seen from Figure 2a that Na atoms form a honeycomb layered sublattice in the ab plane, while Pt atoms form one-dimensional (1D) chains along the c-axis with equal Pt−Pt distance of 2.674 Å, which is close to the Pt−Pt bond length in Li 2 Pt 39,57 and is shorter than those in Pt bulk (2.756 Å) and NaPt 3 (2.700 Å) at 15 GPa. It is noted that Na 5 Pt may also crystallize in the same space group and the crystal structure can be obtained by alternately replacing the Pt layers in Na 2 Pt with Na, as shown in Figure 2b.…”

“…In addition to NaCl, unexpected stoichiometry compounds such as NaCl 7 , NaCl 3 , Na 3 Cl 2 , Na 2 Cl, and Na 3 Cl become stable under high pressures. At ambient pressure, LiPt 7 , LiPt 2 , LiPt, and Li 2 Pt can be obtained at high temperatures. − Among these compounds, Li 2 Pt is known to exist at a normal atmosphere, which is formed by reacting LiH and Pt at 870 K, while pressure can drive its formation at room temperature . Therefore, there is a prospect for the formation of unusual stoichiometric sodium platinides by virtue of pressure.…”

“…36−38 Among these compounds, Li 2 Pt is known to exist at a normal atmosphere, which is formed by reacting LiH and Pt at 870 K, 36 while pressure can drive its formation at room temperature. 39 Therefore, there is a prospect for the formation of unusual stoichiometric sodium platinides by virtue of pressure. NaPt 2 is the only compound known in the Na−Pt binary system at ambient conditions.…”

Direct Visualization of Substitutional Li Doping in Supported Pt Nanoparticles and Their Ultra‐selective Catalytic Hydrogenation Performance

“…Recently, Howies et al. reported a novel intermetallic compound Li 11 Pt 2 , which can be obtained under even harsher conditions [18] . Notice that these bulk phases are unable to be used as catalysts due to the low surface area, limited concentration of exposed metal sites, and high lithium contents.…”

“…[16] Recently, Howies et al reported a novel intermetallic compound Li 11 Pt 2 , which can be obtained under even harsher conditions. [18] Notice that these bulk phases are unable to be used as catalysts due to the low surface area, limited concentration of exposed metal sites, and high lithium contents. Therefore, it is highly important to bridge the knowledge gap between these bulk systems and the analogous nanoparticle system by using the controlled Li doping of supported Pt nanoparticles for catalytic applications.…”