Paired Photoproduction of HO and 3,4-Dihydroisoquinoline Over Covalent Pyrene-(Thio)urea Frameworks with Electron Push-Pull Effect.

Pairing photocatalytic 1,2,3,4-tetrahydroisoquinoline semi-dehydrogenation reaction (THIQ-SDR) with two-electron oxygen reduction reaction (2e ORR) is a green solar to chemical strategy by simultaneously utilizing the photo-excited electrons and holes. However, it is still short of high-efficiency photocatalyst to drive two reactions above. In the present work, crystalline pyrene-thiourea/urea covalent organic frameworks (COF-Py-S and -O) were synthesized and demonstrated as high-performance metal-free photocatalysts.

Membrane-free Electrolysis Production of Hydrogen Peroxide on Low-cost Metal-free Electrocatalysts for Dye Degradation.

The efficient production of hydrogen peroxide (HO) solution was achieved by combining cathodic two-electron oxygen reduction (2e ORR) and anodic two-electron water oxidation (2e WOR) in two half-reaction cells. h-BN loaded on carbon fibers (h-BN@C) is prepared and employed as an anode material to catalyze 2e WOR, while sulfonated commercial BP-2000 carbons (BP-2000-SOH) were prepared as the cathode materials for 2e ORR. In a 2 M KHCO solution, an overall Faradaic efficiency of 97 % and a total HO production rate of 1872 mmol g h over metal-free electrodes were accomplished in a membrane-free flow cell.

Changing Benzoxazole Ring into Nonring Imine Linkages on Covalent Organic Frameworks with Tuning HO Photosynthesis Performance.

Two π-conjugated covalent organic frameworks (COFs) with nonring imine or benzoxazole ring linkages were prepared by reacting 3,3'-dihydrooxybenzidine (BDOH) with 3,5-triformylbenzene (Tb) in the presence or absence of benzimidazole (BDOH-Tb- and BDOH-Tb-). Although two COFs indicated similar composition, crystalline structures, and morphologies, imine-based BDOH-Tb- exhibited a photocatalytic HO production rate of 2490 μmol·g·h in sacrificial reagent-free pure water, higher than that of benzoxazole-based BDOH-Tb- (1168 μmol·g·h). The higher photocatalytic activity of BDOH-Tb- was attributed to its more efficient photoinduced charge separation and utilization efficiency and different 2e ORR active sites over the two COFs.

Robust Covalent Organic Framework Photocatalysts for HO Production: Linkage Position Matters.

Covalent organic frameworks (COFs) are promising photocatalysts for hydrogen peroxide (HO) synthesis. However, the nature of organic polymers makes the balance between high activity and stability challenging. We demonstrate that the linkage position matters in the design of robust COF photocatalysts with durable high activity without sacrificial reagents.

Weakly Hydrophilic Imine-Linked Covalent Benzene-Acetylene Frameworks for Photocatalytic HO Production in the Two-Phase System.

Conversing oxygen (O) to hydrogen peroxide (HO) driven by solar energy is a promising HO onsite production route but often short of efficient and durable photocatalysts. Herein, strong π-π conjugate polycyclic aromatic benzene and acetylene units have been constructed into new covalent organic frameworks (COFs) linked by imine C═N bonding. These COFs demonstrated two-dimensional hexagonal crystalline frameworks with higher crystallinity and larger surface area (>600 m g).

Activated biochar derived from peanut shells as the electrode materials with excellent performance in Zinc-air battery and supercapacitance.

The use of activated biochar-based electrode derived from waste biomass in energy technologies, such as metal-air batteries and supercapacitors, is an important strategy for realizing energy and environmental sustainability in the future. Herein, peanut shells (waste biomass) were employed to prepare activated biochar materials by pyrolysis in molten KCl and heat-treatment. The effective dispersion and corrosion effects of molten salt for the pyrolysis products during pyrolysis obviously increase defects and specific surface area of the activated biochar materials.

3D Graphene-Carbon Nanotube Hybrid Supported Coupled Co-MnO Nanoparticles as Highly Efficient Bifunctional Electrocatalyst for Rechargeable Zn-Air Batteries.

The development of high-efficiency and low-cost catalysts is one of the core and important issues to improve the efficiency of electrochemical reactions on electrodes, and it is also the goal we ultimately pursue in the commercialization of large-scale clean energy technologies, such as metal-air batteries. Herein, a nitrogen-doped graphene oxide (GO)-carbon nanotube (CNT) hybrid network supported coupled Co/MnO nanoparticles (Co/MnO@N-C) catalyst was prepared with a hydrothermal-pyrolysis method. The unique three-dimensional network structure of substrate allowed for the uniform dispersion of Co-MnO nanoparticles in the carbon skeleton.

Covalent pendulous anthraquinone polymers coupled on graphenes for efficient capacitance storage in both alkaline and acidic media.

Novel crystalline covalent organic polymers (COPs) were constructed by reacting 1,4-diaminoanthraquinone with 1,3,5-triformylphloroglucinol or tris(4-formylphenyl)amine (TPDA or TADA). After they were covalently bonded to amine-functionalized graphene oxides, the resulting mesoporous COPs@graphene composites demonstrated efficient capacitance storage performance in both alkaline and acidic media. In particular, the as-synthesized TPDA@graphene displayed a reversible specific capacitance of 522 F g-1 in a 6.

Efficient Nitrate Reduction over Novel Covalent Ag-Salophen Polymer-Derived "Vein-Leaf-Apple"-like Ag@Carbon Structures.

Efficient electrocatalysts for nitrate reduction reaction (NO-RR) that could selectively transfer nitrate into harmless nitrogen are required for water-denitrification treatment. The most widely used electrodes for NO-RR including noble metals, transition metals, and their alloys still face many challenges such as lower selectivity and efficiency, high cost, and easy corrosion properties. Metallic Ag with acceptable cost possesses strong corrosion resistance in electrolysis, but its activity is often incompetent for NO-RR.

Sn(OH)-assisted synthesis of mesoporous Mn-porphyrinic frameworks and their carbon derivatives for electrocatalysis.

5,10,15,20-Tetrakis (4-aminophenyl) Mn-porphyrin and 2,4,6-trihydroxy-1,3,5-benzenetricarbaldehyde were combined into a new mesoporous organic framework by a Schiff-base-type reaction. Sn(OH)x helped in improving the yield of this Mn-COF. Further, S-containing dimethyl sulfoxide solvent molecules were tripped in the pores of Mn-COFs.

Pyrolytic Carbon-coated Cu-Fe Alloy Nanoparticles with High Catalytic Performance for Oxygen Electroreduction.

Well-dispersed carbon-coated or nitrogen-doped carbon-coated copper-iron alloy nanoparticles (FeCu@C or FeCu@C-N) in carbon-based supports are obtained using a bimetallic metal-organic framework (Cu/Fe-MOF-74) or a mixture of Cu/Fe-MOF-74 and melamine as sacrificial templates and an active-component precursor by using a pyrolysis method. The investigation results attest formation of Cu-Fe alloy nanoparticles. The obtained FeCu@C catalyst exhibits a catalytic activity with a half-wave potential of 0.

Bio-inspired chitosan-heme-vitamin B-derived Fe-Co bimetallic-doped mesoporous carbons for efficiently electro-activating oxygen.

A bio-inspired bimetallic Fe- and Co-doped nitrogen-carbon material (Fe-Co-N-C) was synthesized using chitosan and porphyrin-like heme and vitamin B12 precursors. Anionic heme with Fe-N4 moieties and vitamin B12 with Co-N4 moieties were grafted onto the surface of acidic chitosan polymers through interactions with cationic -NH3+, and these polymers were coated onto nano-sized silica spheres to form the composite precursors. The optimised thermolysis of these composites yielded mesoporous carbons with abundant surface Fe-Nx and Co-Nx sites.

Electroactive Cu-P-Coupled Moieties Doped in Hierarchically Porous Carbon as Efficient Catalysts for the Oxygen-Reduction Reaction.

A porous carbon material that was co-doped with copper and phosphorus (Cu-P-C) was synthesized by the direct thermal conversion of [(Ph P) CuCl ] in the channels of an SBA-15 template and found to be an impressive Cu-based electrocatalyst. The prefabricated Cu-P moieties in the starting [(Ph P) CuCl ] were retained during the preparation process of the catalyst. These Cu-P active sites effectively catalyzed the oxygen-reduction reaction (ORR).

Covalent Porphyrin Framework-Derived FeP@FeN-Coupled Nanoparticles Embedded in N-Doped Carbons as Efficient Trifunctional Electrocatalysts.

A new porous covalent porphyrin framework (CPF) filled with triphenylphosphine was designed and synthesized using the rigid tetrakis(p-bromophenyl)porphyrin (TBPP) and 1,3,5-benzenetriboronic acid trivalent alcohol ester as building blocks. The carbonization of this special CPF has afforded coupled FeP and FeN nanoparticles embedded in N-doped carbons (FeP/FeN@N-doped carbons). This CPF serves as an "all in one" precursor of Fe, N, P, and C.

Space-confined synthesis of multilayer Cu-N-doped graphene nanosheets for efficient oxygen electroreduction.

Cu-based carbon electrocatalysts for the oxygen reduction reaction are difficult to compare with the corresponding Fe- or Co-based electrocatalytic materials, owing to their insufficient catalytic activity and stability. Herein, as an impressive Cu-based electrocatalyst, a multilayer Cu-N-doped graphene sheet (Cu-N-GR) is directly synthesized by the thermal conversion of copper(ii) 2,2'-bipyridine in the confined space of lamellar montmorillonites. The open layered morphology of Cu-N-GR materials facilitated the exposure of more active centers and enhanced the flexibility and mobility of charge carriers.

Nanoporous carbon derived from a functionalized metal-organic framework as a highly efficient oxygen reduction electrocatalyst.

High levels of iron-nitrogen doped porous carbon materials are obtained from MOF-253 using a step-by-step post-synthetic modification strategy. MOF-253 possessing open 2,2'-bipyridine nitrogen sites not only serves as a precursor but also provides chelate bonding sites for Fe. Followed by further impregnation of 1,10-phenanthroline, high surface area porous carbon materials are obtained.

Origin of the Ability of α-Fe O Mesopores to Activate C-H Bonds in Methane.

Methane is a most abundant and inexpensive hydrocarbon feedstock for the production of chemicals and fuels. However, it is extremely difficult to directly convert methane to higher hydrocarbons because the C-H bonds in methane are the most stable C-H bonds of all hydrocarbons. The activation of the C-H bonds in methane by using an efficient and mild route remains a daunting challenge.

MIL-100 derived nitrogen-embodied carbon shells embedded with iron nanoparticles.

The use of metal-organic frameworks (MOFs) as templates and precursors to synthesize new carbon materials with controllable morphology and pre-selected heteroatom doping holds promise for applications as efficient non-precious metal catalysts. Here, we report a facile pyrolysis pathway to convert MIL-100 into nitrogen-doped carbon shells encapsulating Fe nanoparticles in a comparative study involving multiple selected nitrogen sources. The hierarchical porous architecture, embedded Fe nanoparticles, and nitrogen decoration endow this composite with a superior oxygen reduction activity.

New heterometallic zirconium metalloporphyrin frameworks and their heteroatom-activated high-surface-area carbon derivatives.

Four cubic zirconium-porphyrin frameworks, CPM-99(H2, Zn, Co, Fe), were synthesized by a molecular-configuration-guided strategy. Augmentation of meso-substituted side arms (with double-torsional biphenyl rings) of tetratopic porphyrin linkers leads to a successful implementation of zirconium-carboxylate frameworks with cubic 2.5 nm cage.

From cage-in-cage MOF to N-doped and Co-nanoparticle-embedded carbon for oxygen reduction reaction.

By one-step pyrolysis of a unique "cage-in-cage" cobalt metal-organic framework, nitrogen-doped carbon cubes embedded with numerous metallic Co nanoparticles were obtained. A considerable amount of Co particles was encapsulated in thin carbon shells and formed the core-shell-like Co@C structure. With about 60 wt% Co particles in the prepared sample, the nanocomposites of Co nanoparticles and nitrogen-doped carbon show electrocatalytic activity for the oxygen reduction reaction (ORR) with an efficiency comparable to the commercial Pt/C catalyst, but with better durability and methanol-tolerance performance.

Efficient oxygen reduction by nanocomposites of heterometallic carbide and nitrogen-enriched carbon derived from the cobalt-encapsulated indium-MOF.

By one-step pyrolysis of an indium-MOF with entrapped cobalt dimers in the presence of melamine, heterometallic carbide nanoparticles (Co3InC0.75) embedded in nitrogen-enriched carbon have been prepared and found to exhibit efficient electrocatalytic activity for oxygen reduction reaction with high durability and methanol-tolerance properties.

Ordered mesoporous Fe-porphyrin-like architectures as excellent cathode materials for the oxygen reduction reaction in both alkaline and acidic media.

Iron ORR: An ordered, mesoporous, Fe-porphyrin-like material was created through the nanocasting and pyrolysis of traditional Fe-N4 porphyrins. The resulting nonprecious metal electrocatalyst was used for the oxygen reduction reaction in both alkaline and acidic media.

A three-dimensional supramolecular vanadium hydroxylamide complex: poly[di-mu2-aqua-bis(hydroxylamido)-mu3-malonato-oxidosodiumvanadium(V)].

The crystal structure of the title compound, [NaV(C3H2O4)(NH2O)2O(H2O)2], is built up of NaO6 and VO5N2 polyhedra connected through malonate bridges. The NaO6 octahedra are linked by edge sharing in the equatorial plane to form one-dimensional infinite chains. These chains are linked together by the malonate bridges to form two-dimensional layers.