Hollow Ru/RuO2 nanospheres with nanoparticulate shells for high performance electrocatalytic oxygen evolution reactions.

This work shows that hollow Ru/RuO2 nanoparticles having nanoparticulate shells (HN-Ru/RuO2) can be prepared using hollow microporous organic polymers with Ru species (H-MOP-Ru) as precursors. Using silica spheres as templates, H-MOPs were prepared through the Sonogashira-Hagihara coupling of 1,3,5-triethynylbenzene with 2,3-ethoxymethylenedioxy-1,4-diiodobenzene. Acid hydrolysis of cyclic ethyl orthoformate protecting groups generated catechol moieties to form H-MOP-Cat. Then, H-MOP-Ru was obtained by incorporating Ru species into H-MOP-Cat. Heat-treatment of H-MOP-Ru under air induced the formation of HN-Ru/RuO2 with a diameter of 61 nm and shells consisting of 6-7 nm nanoparticles. Due to the hollow structure and nanoparticulate shells, HN-Ru/RuO2 showed a high surface area of 80 m2 g-1 and a pore volume of 0.18 cm3 g-1. The HN-Ru/RuO2 showed enhanced electrocatalytic performance for the oxygen evolution reaction (OER) with an overpotential of 295 mV @ 10 mA cm-2 and a Tafel slope of 46 mV dec-1 in alkaline electrolyte, compared with control RuO2 such as commercial Ru/RuO2 nanoparticles (A-Ru/RuO2) and home-made Ru/RuO2 nanoparticles (N-Ru/RuO2) prepared via the same synthetic procedure as HN-Ru/RuO2. While HN-Ru/RuO2 inevitably contained Pd originated from coupling catalysts, it showed superior performance to Ru/RuO2 nanoparticles with the same Pd content (N1-Ru/RuO2), indicating that the efficient electrocatalytic performance of HN-Ru/RuO2 is attributable to its hollow structure and nanoparticulate shells.

Uniform Growth of Nanocrystalline ZIF-8 on Cellulose Nanocrystals: Useful Template for Microporous Organic Polymers.

Zeolitic imidazolate framework (ZIF-8) nanocrystals were uniformly grown on the surface of cellulose nanocrystals (CNCs) to give a hybrid material, ZIF@CNCs. By varying the stoichiometry of the components, it was possible to control the size of the ZIF-8 crystals grown on the CNC surface. Optimized ZIF@CNC (ZIF@CNC-2) was used as a template to synthesize a microporous organic polymer (MOP), ZIF@MOP@CNC. After etching the ZIF-8 with 6 M HCl solution, a MOP material with encapsulated CNCs (MOP@CNC) was formed. Zinc coordination into the porphyrin unit of the MOP yielded the ship-in-a-bottle structure, Zn MOP@CNC, comprised of CNCs encapsulated within the Zn-MOP. In comparison to ZIF@CNC-2, Zn MOP@CNC showed better catalytic activity and chemical stability for CO2 fixation, converting epichlorohydrin to chloroethylene carbonate. This work demonstrates a novel approach to create porous materials through CNC templating.

Valorization of Click-Based Microporous Organic Polymer: Generation of Mesoionic Carbene-Rh Species for the Stereoselective Synthesis of Poly(arylacetylene)s.

This work reports the functionalization of azide-alkyne click-based microporous organic polymer (CMOP). The generation of triazolium salts and successive deprotonation induced mesoionic carbene species in hollow CMOP (H-CMOP). Rh(I) species could be coordinated to the mesoionic carbene species to form H-CMOP-Rh, showing excellent heterogeneous catalytic performance in the stereoselective polymerization of arylacetylenes.

Iron Coordination to Hollow Microporous Metal-Free Disalphen Networks: Heterogeneous Iron Catalysts for CO2 Fixation to Cyclic Carbonates.

This work shows that a hollow and microporous metal-free N,N'-phenylenebis(salicylideneimine) (salphen) network (H-MSN) can be engineered by Sonogashira coupling of [tetraiodo{di(Zn-salphen)}] building blocks with 1,4-diethynylbenzene in the presence of silica templates and by successive Zn and silica etching. Iron(III) ions could be incorporated into the H-MSN to form hollow and microporous Fe-disalphen networks (H-MFeSN) with enhanced microporosity and surface area. The H-MFeSN showed efficient catalytic performance and recyclability in the CO2 conversion to cyclic carbonates.

Nanoparticulate and microporous solid acid catalysts bearing aliphatic sulfonic acids for biomass conversion.

This work introduces new nanocatalytic systems based on microporous organic network (MON) chemistry for fructose conversion to 5-hydroxymethylfurfural (HMF). The efficiency of the catalytic systems could be improved through the size-controlled synthesis of MON materials. Through a predesigned building block approach and a post-synthetic modification, aliphatic sulfonic acid groups were incorporated into nano-sized MON materials to form N-MON-AS. The N-MON-AS showed selective conversion of fructose to HMF in up to 91% yield at 100 °C and good recyclability.

Network-controlled unique reactivities of carbonyl groups in hollow and microporous organic polymer.

Hollow and microporous organic network bearing alkynone moieties was prepared via carbonylative Sonogashira coupling. The carbonyl groups in the network showed unusual chemical reactivities, compared with those of a model alkynone compound. The observed differences between the reactivities of alkynones in the molecule and in the network were analyzed based on the "network effect".

Dual role of Cu2O nanocubes as templates and networking catalysts for hollow and microporous Fe-porphyrin networks.

Cu2O nanocubes were used for the synthesis of hollow and microporous Fe porphyrin networks (H-MFePN). In this synthesis, Cu2O nanocubes performed not only as networking catalysts but also as shape controlling templates. MFePN were formed on the surface of the Cu2O nanocubes through azide-alkyne cycloaddition of tetrakis(4-ethynylphenyl) Fe-porphyrin with 1,4-diazidobenzene. H-MFePN showed excellent catalytic activities in carbene insertion into N-H bonds, maintaining their activities during five recycle tests.