A Single-Crystal Open-Capsule Metal–Organic Framework

• Published in: Journal of the American Chemical Society Vol. 141; no. 19; pp. 7906 - 7916
• Main Authors: Wei, Yong-Sheng, Zhang, Mei, Kitta, Mitsunori, Liu, Zheng, Horike, Satoshi, Xu, Qiang
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 15.05.2019
• Subjects: batteries; carbon; carbon nanotubes; catalysts; catalytic activity; coordination polymers; crystal structure; drugs; electrochemistry; hydrogen production; iodine; melamine; nanoparticles; oxygen; oxygen production; phosphides; sulfur; synergism
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.9b02417

Micro-/nanocapsules have received substantial attention due to various potential applications for storage, catalysis, and drug delivery. However, their conventional enclosed non-/polycrystalline walls pose huge obstacles for rapid loading and mass diffusion. Here, we present a new single-crystal capsular-MOF with openings on the wall, which is carefully designed at the molecular level and constructed from a crystal-structure transformation. This rare open-capsule MOF can easily load the largest amounts of sulfur and iodine among known MOFs. In addition, derived from capsular-MOF and melamine through pyrolysis–phosphidation, we fabricated a nitrogen-doped capsular carbon-based framework with iron–nickel phosphide nanoparticles immobilized on capsular carbons interconnected by plentiful carbon nanotubes. Benefiting from synergistic effects between the carbon framework and highly surface-exposed phosphide sites, the material exhibits efficient multifunctional electrocatalysis for oxygen evolution, hydrogen evolution, and oxygen reduction, achieving well-qualified assemblies of an overall water splitting (low potential of 1.59 V at 10 mA·cm–2) and a rechargeable Zn–air battery (high peak power density of 250 mW·cm–2 and excellent stability for 500 h), which afford remarkably practical prospects over previously known electrocatalysts.