Porous Iron Single Crystals at 2 cm Scale Delivering Enhanced Electrocatalysis Performance

Porous single crystals would significantly enhance their catalysis functionalities owing to the combination of structural coherence and porous microstructures. Porous single crystals have wormhole microstructures and then we define them as wormcrystals. The twisted surfaces in porous microstructures would produce surface lattice distortions that give rise to high-energy active surfaces. Here we grow porous iron single crystals at an unprecedented 2 cm scale with a lattice reconstruction strategy and create high-energy surfaces through the control of lattice distortions within a thickness region of 1~2 nm. The porous iron crystal therefore boosts electrochemical reduction of nitrobenzene to aminobenzene with ~100% conversion and > 95% selectivity. The exceptionally high current densities with porous iron crystals represent the first level electrocatalysis performance. The current work would open a new pathway not only to the creation of high energy surfaces but also to the growth of porous single crystals at large scales in wealth of other materials.

Porous Iron-and Cobalt-based Single Crystals with Enhanced Electrocatalysis Performance

Porous single crystals have the characteristics of long-range ordering structure and large specific surface area,which will significantly enhance their electrochemical performance.Here,we report a method different from the conventional porous single crystal growth method.This method is to directly convert single crystal precursors Co_(3)O_(4) and Fe_(3)O_(4) into Co_(2)N and Fe_(2)N,and then further reduces them to porous single crystals Co and Fe particles under H2/Ar atmosphere.The removal of O^(2–)in the lattice channel at the pressure of 25~300 torr and the temperature of 300~600℃ will promote nitridation of the single-crystalline Co–O and Fe–O frames,and further remove N^(3–)in H2/Ar atmosphere and recrystallize as Co and Fe.These porous single crystals exhibit enhanced electrochemical properties due to their structural coherence and highly active surface.We demonstrated that the aminobenzene yield was up to 91%and the selectivity reached 92%in the electrochemical reduction of nitrobenzene.

Identifying and Engineering Active Sites at the Surface of Porous Single-Crystalline Oxide Monoliths to Enhance Catalytic Activity and Stability

Identifying and engineering active sites play a key role in many catalytic reactions.Herein,we create well-defined surface structures through the growth of porous single-crystalline Mn_(3)O_(4) and Mn_(2)O_(3) monoliths at centimeter scale and confine atomically dispersed Pt ions in the lattice at the twisted surface to construct isolated active sites.The activation of lattice oxygen linked to isolated Pt ions is much more effective than the lattice oxygen linked to Mn ions in local structures,leading to an approximately sevento eightfold enhancement of surface oxygen exchange coefficients for catalytic CO oxidation.The active structures of PtO_(1.5) and PtO_(1.4) confined at the well-defined surfaces contribute to the efficient activation of lattice oxygen linked to Pt ions in local structures in addition to the chemisorption of CO in the oxidation reaction.We demonstrate the complete CO oxidation with air at 65℃ without degradation being observed even after continuous operation of 300 h.

Porous zinc(Ⅱ)-organic framework with potential open metal sites:Synthesis,structure and property

Reaction of Zn(NO3)2.6H2O with 5-(isonicotinamido) isophthalic acid(H2INAIP) in N,N-dimethylformamide(DMF) affords a new three-dimensional(3D) coordination polymer {[Zn(INAIP)(DMF)].0.5DMF.4H2O}n(1).The X-ray crystallographic structural analysis reveals that complex 1 is a 3D porous framework containing a potential open metal site inside the pores.Topology analysis confirms that complex 1 is a two-fold interpenetrated(10,3)-b net with both metal ion and ligand acting as 3-connecting nodes.The thermal stability,variable temperature X-ray diffraction pattern and N2 adsorption property of the complex are investigated.