Conductive Metal/Covalent Organic Frameworks for CO2 Electroreduction

Porous crystalline metal-organic frameworks（MOFs） and covalent organic frameworks（COFs） are promising platforms for electrocatalytic reduction of CO₂（CO₂RR） due to their large CO₂ adsorption uptakes and periodically arranged single active sites. However, the applications in CO₂RR of the traditional MOFs and COFs are greatly limited by their low electron conductivity. In recent years, numerous types of MOFs and COFs with high intrinsic conductivity have...     

Self-assembly of single metal sites embedded covalent organic frameworks into multi-dimensional nanostructures for efficient CO2 electroreduction

Morphology-controlled electrocatalysts with the ability of CO₂adsorption/activation, mass transfer, high stability and porosity are much desired in electrochemical CO₂reduction reaction（CO₂RR）. Here, three kinds of multi-dimensional nanostructures（i.e., hollow sphere, nanosheets and nanofibers） have been successfully produced through the modulation of porphyrin-based covalent organic frameworks（COFs）with various modulators. The obtained nanostructures with high-s...     

Enhancing photocatalytic performance of metal-organic frameworks for CO2 reduction by a bimetallic strategy

Metal-organic frameworks（MOFs） as a type of crystalline heterogeneous catalysts have shown potential application in photocatalytic CO₂ reduction.However,MOF catalysts with high efficiency and selectivity are still in pursuit.Herein,by a bimetallic strategy,the catalytic performance of a Co-MOF for photocatalytic CO₂ reduction was enhanced.Specifically,the Co-MOF based on 4,5-dicarboxylic acid（H₃ IDC） and4,4’-bipydine（4,4’-bpy） can catalyze CO₂ reductio...     

Synthesis of Axially Coordinated Cobalt Porphyrin/graphene Oxide Nanocomposite for Enhanced Electrocatalytic CO2 Reduction to CO

The electrocatalysts containing cobalt-pyrrolic nitrogen-carbon （Co-N₄-C） moiety for CO₂ reduction reaction （CO₂RR） have caught much attention.However,the effects of Co valence state and its synergy with graphene substrate are not clear yet.In this work,cobalt porphyrin （Co TPP） molecule with the intrinsic Co-N₄-C moiety is successfully combined with graphene oxide （GO） via three kinds of liquid-phase methods.The ratio of Co TPP to GO and the valence s...     

Crystallization and morphology of star-shaped polyethylenoxyde-b-polycaprolactone under high pressure carbon dioxide

Atomic force microscopy（AFM）,wide-angle X-ray diffraction（WAXD） and differential scanning calorimetry are used to analyze the crystallization morphology and melting behavior of 4-arm PEO-b-PCL under high-pressure CO₂.It is demonstrated that CO₂ has certain effect on the melting and crystallization behavior of the samples.After crystallization under CO₂ at 4 MPa,spherulites with concentric ring-banded structure are formed which are composed of crystals with periodic thickness variation,and the band distance decreases with increasing treatment pressure.Due to the plasticization effect of CO₂,depression of the melting temperature is observed with sorption of CO₂ in polymers.     

Two isostructural Ni(Ⅱ)/Co(Ⅱ)-based metal-organic frameworks for selective dye adsorption and catalytic cycloaddition of CO2 with epoxides

Two isostructu ral Ni(Ⅱ)/Co(Ⅱ)-based metal-organic frameworks(MOFs),namely {[M₃(L)₂(bpb)₃(H₂ O)₄]·2 DMF·2 H₂O}_n [M=Ni(HL-5,HL is short for Hui-Ling Liu);M=Co(HL-6);H₃ L=2',6'-dimethyl-[1,1'-biphenyl]-3,4',5-tricarboxylic acid;bpb=1,4-bis(pyrid-4-yl)benzene],have been hydrothermally synthesized and structu rally characterized.Both HL-5 and HL-6,which have the same three-interpenetrated3 D pillared-layer framework with sqc306 type topology,present good selective methyl orange(MO)adsorption over rhodamine B(RhB).Moreover,the catalytic CO₂ cycloaddition properties with epoxides of the two MOFs have also been studied at ambient pressure and temperature.     

Recent Advances on Metal-Organic Frameworks in the Conversion of Carbon Dioxide

With the development of modern industry,global warming is becoming a challenging issue due to the emissions of large quantities of greenhouse gases,mainly carbon dioxide(CO₂).The conversion of CO₂to useful compounds is considered as an effective and economic way to solve such a climate problem.Metal-organic frameworks(MOFs)are an emerging class of porous crystalline materials that have shown great potential in the conversion of CO₂.The advantages of MOFs in CO 2 conversion lie in their high surface areas,adjustable pore size,and high porosity.More importantly,desirable functional sites can be easily designed and precisely installed to the pore wall of target MOFs by pre-assembly and/or post-synthetic modification(PSM)ways.This review summarizes the recent advances in constructing MOF catalysts for the application in CO₂conversion.We believe that the design and synthesis of MOF catalysts for CO₂conversion can be a promising way to solve the“greenhouse effect”.     

Enhancing the process of CO2 reduction reaction by using CTAB to construct contact ion pair in Li-CO2 battery

Aprotic Li-CO₂ batteries have attracted growing interest due to their high theoretical energy density and its ability to use green house gas CO₂ for energy storage.However,the poor ability of activating CO₂ in organic electrolyte often leads to the premature termination of CO₂ reduction reaction （CO₂RR） directly.Here in this work,cetyl trimethyl ammonium bromide （CTAB） was introduced into a dimethyl sulfoxide（DMSO） based Li-CO₂ ba...     

Surface interrogation mode of scanning electrochemical microscopy for oxidation study of adsorbed CO generated from serine on platinum

We report a new method for detection and oxidation of adsorbed carbon monoxide(CO_（ads）) generated from serine on a polycrystalline platinum ultramicroelectrode（UME） by bromine（Br₂） using in situ surface interrogation（SI） mode of scanning electrochemical microscopy（SECM）.In the SI mode,tip and substrate are both Pt UMEs,and CO_（ads） on Pt substrate,generated from serine,can be oxidized by the tip-generated Br₂ giving a positive response.Dosing CO_（ads） from serine instead of purging CO gas expands the newly introduced reaction of Br₂ with CO_（ads） and further enhances the hope to get rid of CO_（ads） on Pt for fuel cells.     

Syngas production in a novel perovskite membrane reactor with co-feed of CO2

Partial oxidation of methane（POM） co-fed with CO₂ to syngas in a novel catalytic BaCo_0.6Fe_0.2Ta_0.2O_3-δ oxygen permeable membrane reactor was successfully reported.Adding CO₂ to the partial oxidation of methane reaction not only alters the ratio of CO/H₂,but also increases the oxygen permeation flux and CH₄ conversion.Around 96%CH₄ conversion with more than 93%CO₂ conversion and 100%CO selectivity is achieved,which shows an excellent reaction performance.A steady oxygen permeation flux of 15 mL/（cm² min） is obtained during the 100-h operation,which shows good stability as well.     

The Z-scheme g-C3N4/3DOM-WO3 photocatalysts with enhanced activity for CO2 photoreduction into CO

The catalytic performance of light-derived CO₂reduction with H₂O is strongly dependent on the separation efficiency of photogenerated carriers.Herein,the direct Z-scheme catalysts （g-C₃N₄/3DOM-WO₃）of graphitic carbon nitride （g-C₃N₄） nanosheets decorated three-dimensional ordered macroporous WO₃（3DOM-WO₃） were successfully fabricated by using the in-situ colloidal crystal template method.The slow l...     

Achieving simultaneous Cu particles anchoring in meso-porous TiO2 nanofabrication for enhancing photo-catalytic CO2 reduction through rapid charge separation

A facile solvo-thermal approach was successfully employed to prepare titanium oxide（TiO₂） nanoaggregates with simultaneous copper particles anchoring.The as-synthesized composite could convert CO₂ into CH₄ and CO products under simulated solar irradiation.The impact of copper loading amounts on the photo-reduction capability was evaluated.It was found proper amount of Cu loading could enhance the activity of CO₂ photo-reduction.As a result,the optimal ...     

Review on electrochemical carbon dioxide capture and transformation with bipolar membranes

Anthropogenic carbon dioxide(CO₂ ) emission from the combustion of fossil fuels aggravates the global greenhouse effect. The implementation of CO₂ capture and transformation technologies have recently received great attention for providing a pathway in dealing with global climate change. Among these technologies, electrochemical CO₂ capture technology has attracted wide attention because of its environmental friendliness and flexible operating processes. Bipolar ...     

Alternating copolymerization of cyclohexene oxide and carbon dioxide under cobalt porphyrin catalyst

Cobalt porphyrin complexes（TPPCo^ⅢX）（TPP = 5,10,15,20-tetraphenyl-porphyrin;X = halide） in combination with bis（triphenylphosphine） iminium chloride（PPNCl） were used for the copolymerization of cyclohexene oxide and CO₂. The highest turnover frequency of 67.2 h^-1 was achieved after 13 h at 20℃,and the obtained poly（1,2-cyclohexylene carbonate）（PCHC） showed number average molecular weight（M_n） of 10×10³.Though the obtained PCHC showed atactic structure,the m-centered tetrads content reached 58.1%at CO₂ pressure of 1.0 MPa,and decreased to 51.9%at CO₂ pressure of 6.0 MPa,indicating that it was inclined to form atactic polymer at high CO₂ pressure.     

Crystal structure and DNA binding studies of a cobalt(Ⅱ) complex containing mixed-ligands of 1,10-phenathroline and glycollic acid

A cobalt（11） complex containing mixed-ligands of 1,10-phenathroline（phen） and glycollic acid（GA）.|Co（GA）₂（phen）| was synthesized and its structure was characterized by X-ray diffraction.The interaction of the complex with DNA was investigated by electronic absorption spectra and electrochemical methods.Electronic absorption spectrum experiments showed that after interaction with DNA.the characteristic absorption peaks of |Co（GA）₂（phen）| underwent hypochromic effect as well as redshift. Also,the binding strength of 3.8×10⁴L/mol was estimated by titration method.Electrochemical assays revealed that the redox peak currents of the complex decreased obviously accompanied by a positive shift of the formal potential after association with DNA.All these results revealed that the synthesized cobalt complex bound with DNA via an intercalation mode.     

CO2-adsorbent spongy electrode for non-aqueous Li–O2 batteries

Regulation of the Li₂CO₃ byproduct is the most critical challenge in the field of non-aqueous Li–O₂ batteries.Although considerable efforts have been devoted to preventing Li₂CO₃ formation,no approaches have suggested the ultimate solution of utilizing the clean Li₂O₂ reaction instead of that of Li₂CO₃.Even if extremely pure O₂ is used in a Li–O₂ cell,its complete elimination is impossible,eventually generating CO₂ gas during charge.In this paper,we present the new concept of a CO₂-adsorbent spongy electrode(CASE),which is designed to trap the evolved CO₂ using adsorption materials.Various candidates composed of amine functional groups(–NH2)for capturing CO₂ were screened,with quadrapurebenzylamine(QPBZA)exhibiting superior CO₂-adsorbing ability among the proposed candidates.Accordingly,we fabricated the CASE by sandwiching QPBZA between porous carbon layers,which facilitated the transport of gaseous products.The new electrode was demonstrated to effectively capture the evolved CO₂ during charge,therefore altering the reaction pathways to the ideal case.It is highly advantageous to mitigate the undesirable CO₂ incorporation in the next discharge,resulting in improved cyclability.This novel concept of a CO₂-sponging electrode provides an alternative route to the realization of practically meaningful Li–O₂ batteries.     

Solar-driven CO2 conversion to methane and methanol using different nanostructured Cu2O-based catalysts modified with Au nanoparticles

This work describes the use of TiO₂ nanotubes-based electrodes(TNT) modified with Cu₂O nanostructures and gold nanoparticles for the photoelectroreduction of CO₂ to produce value-added compounds.A thin layer of polydopamine was used as both an adherent agent and an electron transfer mediator,due to its π-conjugated electron system.The highest production yield was achieved using a TNT@PDA/Nc/Au^40% electrode,with Faradaic efficiencies of 47.4%(110.5 μM c...     

DFT studies on the origin of regioselective ring-opening of terminal epoxides during copolymerization with CO<Subscript>2</Subscript>

This report presents a detailed density functional theory（DFT） study on the difference in regioselectivity for the copolymerization reactions of styrene oxide versus propylene oxide with CO₂ utilizing binary（salen）cobalt（Ⅲ） catalyst systems. This study focuses on the discrepancy of regioselective ring-opening of two terminal epoxides during the copolymerization with CO₂. It was found that the nucleophilic ring-opening of styrene oxide occurred predominantly at the methine C_a―O bond due to the election delocalization of phenyl group to stabilize the transition state for the methine C―O bond cleavage.     

Regulating the nucleation of Li2CO3 and C by anchoring Li-containing carbonaceous species towards high performance Li-CO2 batteries

Li-CO₂ batteries provide an attractive and potential strategy for CO₂ utilization as well as energy conversion and storage with high specific energy densities.However,the poor reversibility caused by the decomposition obstacles of Li₂CO₃ and C products is still a challenge for Li-CO₂ batteries,which seriously influences its electrochemical performances.Herein,a free-standing MnOOH arrays cathode has been prepared and employed in Li-CO₂ battery,which realizes a great improvement of electrochemical performances by adjusting the discharge products distribution.Experiments coupled with theoretical calculations verifies that the formation of Li-containing carbonaceous species(LiCO₂,LiCO and Li₂ CO₃)bonded with MnOOH through Li ion regulates the nucleation behavior of Li₂CO₃ and C,making them grown on MnOOH uniformly.The fine Li₂ CO₃ grains(with a size about 5 nm)embedded into carbon matrix greatly enlarges the contact interface between them,facilitating the transmission of electrons through the discharge products and finally improves CO₂ evolution activity.This ingenious design strategy of regulating discharge products distribution to improve electrochemical performances provides a promising way to develop advanced Li-CO₂ batteries.     

Spectral and chemical monitoring of cyclo-addition reaction of CO2 with poly(MMA-co-GMA) copolymers

This paper deals with the monitoring cyclo-addition of CO₂ to methyl methacrylate（MMA）-glycidyl methacrylate （GMA） copolymers using spectral（¹H-NMR and FTIR） and chemical（elemental analysis and titration） methods.Thus, poly（MMA-co-GMA）,was first prepared via solution polymerization.The copolymer was then treated with CO₂ gas flow in the presence of cetyltrimethyl ammoniumbromide as a catalyst.In terms of the carbonation reaction time,the terpolymer poly（MMA-co-GMA-co-2-oxo-l,3-dioxolane-4-yl-methyl methacrylate） was prepared in various yield of CO₂ fixation （>90%）.The peak intensity changes in the ¹H-NMR and FTIR spectra provided excellent demonstrative techniques to monitor the carbonation reaction progression.In a comparative analytical viewpoint,the NMR and elemental analysis were recognized to be the most accurate ways to follow the cyclo-addition reaction progression.However,titration was recognized to be the most preferred method,because it is a very inexpensive,facile and available method with a reasonable costaccuracy balance.