Hydrogen storage in Pd nanocrystals covered with a metal–organic framework

Abstract

Hydrogen is an essential component in many industrial processes. As a result of the recent increase in the development of shale gas, steam reforming of shale gas has received considerable attention as a major source of H2, and the more efficient use of hydrogen is strongly demanded. Palladium is well known as a hydrogen-storage metal and an effective catalyst for reactions related to hydrogen in a variety of industrial processes. Here, we present remarkably enhanced capacity and speed of hydrogen storage in Pd nanocrystals covered with the metal-organic framework (MOF) HKUST-1 (copper(II) 1,3,5-benzenetricarboxylate). The Pd nanocrystals covered with the MOF have twice the storage capacity of the bare Pd nanocrystals. The significantly enhanced hydrogen storage capacity was confirmed by hydrogen pressure-composition isotherms and solid-state deuterium nuclear magnetic resonance measurements. The speed of hydrogen absorption in the Pd nanocrystals is also enhanced by the MOF coating.

Multifunctional metal–organic frameworks: from academia to industrial applications

“…[93][94][95][96] Li et al prepared the Pd@HKUST-1 composite material by using a facile reactive seeding methodology: Pd crystals, as nanocubes, work as seed sites for MOF growth (Figure 4). 93 Pd nanoparticles were coated by preparing a solution composed of Pd nanocubes, the precursors (trimesic acid and Cu 2+ cations) of HKUST-1 and ethanol. Hydrogen pressure-composition isotherms and solidstate deuterium nuclear magnetic resonance (NMR) experiments suggest that Pd nanocubes coated with HKUST-1 MOF material exhibit two times more hydrogen storage capacity than the uncoated Pd nanocrystals.…”

Polymers for carrying and storing hydrogen

“…Outstanding surface areas nearly reaching 5000 m 2 g − 1 and high pore volumes confer considerable potential to MOFs as prospective materials for hydrogen storage. 16,17 A wide range of varying topologies and pore sizes from combinations of organic ligands and metal connectors has been explored. For example, highly porous cubic frameworks comprised of Zn 4 O(CO 2 ) 6 units coordinated by an octahedral array of 1,4-benzenedicarboxylate and benzene tribenzoate groups adsorbed 1 wt% hydrogen at room temperature (2 MPa) and 4.5-7.5 wt% at 78 K (0.08 MPa).…”

Application of metal and metal oxide nanoparticles@MOFs

“…Characterization by X-ray diffraction revealed that the high capacity at room temperature is partially explained by formation of Pd hydride that occurs readily at room temperature. Recently, Kitagawa and co-workers have significantly improved hydrogen storage capacity of Pd nanoparticles by employing a MOF coating [11]. Here, samples of Pd nanocrystals were successfully covered in the HKUST-1 leading to a drastic increase in the storage capacity and kinetics of hydrogen adsorption compared to the base Pd nanocubes (Fig.…”

“…These unique features have led researchers to explore combining MOFs with other functional materials to form novel composites with advanced properties [6]. Indeed, ceramics, metal nanoparticles, polymers and biomolecules have been combined with MOFs to afford new materials that have demonstrated unprecedented performance in the areas of catalysis [7], molecular separations [8], sensing [9], plasmonics [10], gas storage [11], controlled guest release [12,13], and protection of biomacromolecules [14]. The most widely studied of these composite systems are based on integrating metal and metal oxide nanoparticles with MOFs.…”