Novel hydrogen storage properties of palladium nanocrystals activated by a pentagonal cyclic twinned structure

Abstract

Researchers appear to have neglected a special form of crystallites, pentagonal cyclic twinning, in which an obvious two-dimensional lattice expansion exists leading to novel physical-chemical properties associated with the changes in geometric and electronic structures. Using the storage and release of hydrogen in Pd nanocrystals as a probe, we have found that icosahedral pentagonal cyclic twinned Pd nanocrystals had distinct hydrogen storage properties, due to the two-dimensional lattice expansions, quite different from those of the octahedral single crystalline counterpart. In addition, the two-dimensional lattice expansion in pentagonal cyclic twinned Pd nanocrystals causes a change in electronic structure, which results in novel catalytic properties involving in situ formation of PdH x pentagonal cyclic twinned nanocrystals.Noble metal materials enjoy widespread application in many important fields such as catalysis, sensing, nanomedicine and energy storage [1][2][3][4][5]. With the growing demand for, and decreasing reserves of, noble metals, considerable efforts have been devoted to enhancing the performance of noble metals in order to minimize their usage. Among the various strategies which have been developed, control of the size, morphology or surface structure of noble metal-based nanoparticles are considered as very useful approaches [6][7][8]. However, researchers may have neglected a special form of crystallite formation, pentagonal cyclic twinning (PCT), in which a two-dimensional (2D) lattice expansion exists. This expansion results in novel physical-chemical properties due to the changes in geometric and electronic structures [9][10][11]. In fact, PCT usually occurs in crystals of face centered cubic (fcc) structures, especially in noble metal nanocrystals (NCs) [12][13][14][15][16][17][18][19]. In the past few years, researchers have gained a deep understanding of the formation Nano Research

Interstitial Hydrogen Atom Modulation to Boost Hydrogen Evolution in Pd-Based Alloy Nanoparticles

“…Notably, hydrogen, as the smallest atom, is easily incorporated with metals to form metal hydrides. − Metal hydride complexes are key intermediates in proton reduction, H 2 oxidation, and CO 2 hydrogenation. − However, implementing a metal hydride system as an alkaline HER catalyst remains a challenge, even though the reaction is performed in a H 2 -enriched environment. The major limiting reasons are that traditional metal hydrides obtained under high-pressure conditions are unstable and hydrogen atoms gradually leach out over time even at room temperature; − furthermore, the low adsorption of intermediates on usual monometal-component hydrides is not favorable for the alkaline HER. , …”

Effect of the Inherent Structure of Rh Nanocrystals on the Hydriding Behavior under Pressure

“…The intrinsic PCT consists of 20 (111) faceted tetrahedral units with 30 twin boundaries, in which a two-dimensional (2D) lattice expansion exists. The novel properties of metal NCs are induced by expansion due to the changes in geometry and electronic structure . For the hydrogenation reaction, the thermodynamics of the reaction is regarded as a key point for understanding the nanostructural effects on the properties of the metal hydrides.…”

Emerging interstitial/substitutional modification of Pd-based nanomaterials with nonmetallic elements for electrocatalytic applications

“…Recently, Xie et al found that icosahedral PdH 0.706 NCs and octahedral PdH 0.706 NCs could be produced by charging icosahedral Pd NCs and octahedral Pd NCs ( pre-treated with I − ) in H 2 at 2 atm pressure for 1 h at room temperature. 44 Powder X-ray diffraction (PXRD) patterns indicated that the diffraction peaks of both the obtained PdH 0.706 shifted to Fig. 2 Representative nonmetallic elements in the periodic table of the elements used for insertion into the Pd lattice to form binary PdL x .…”