Converting metal-organic framework particles from hydrophilic to hydrophobic by an interfacial assembling route

Here we propose to modify the hydrophilicity of metal-organic framework (MOF) particles by an interfacial assembling route, which is based on the surface-active nature of MOF particles. It was found that hydrophilic UiO-66-NH₂ particles can be converted to hydrophobic particles through an oil-water interfacial assembling route. The underlying mechanism for the conversion of UiO-66-NH₂ was investigated by X-ray photoelectron spectroscopy and FT-IR spectroscopy. It was revealed that the close assembly of UiO-66-NH₂ particles at the oil-water interface strengthens the coordination between organic ligands and metal ions, which results in a decrease in the proportion of hydrophilic groups on UiO-66-NH₂ particle surfaces. Hydrophobic UiO-66-NH₂ particles show improved adsorption capacity for dyes in organic solvents compared with pristine UiO-66-NH₂ particles. It is expected that the interfacial assembling route can be applied to the synthesis of different kinds of MOF materials with tunable hydrophilicity or hydrophobicity required for diverse applications

Single atom and defect engineering of CuO for efficient electrochemical reduction of CO 2 to C 2 H 4

Electrochemical CO2 transformation to high‐value ethylene (C2H4) at high currents and efficiencies is desired and yet remains a grand challenge. We show for the first time that coupling single Sb atoms and oxygen vacancies of CuO enable synergistic electrocatalytic reduction of CO2 to C2H4 at low overpotentials. Highly dispersed Sb atoms occupying metal substitutional sites of CuO are synthesized under mild conditions. The overall CO2 reduction faradaic efficiency (FE) reaches 89.3 ± 1.1% with an FE toward C2H4 exceeding 58.4% at a high‐current density of 500 mA/cm2. Addition of the p‐block metal is found to induce transformation of CuO from flakes to nanoribbons rich in nanoholes and oxygen vacancies, greatly enhancing CO2 adsorption and activation while suppressing hydrogen evolution. Further density functional theory calculations with in situ X‐ray diffraction reveal that combining Sb sites and oxygen vacancies prominently lessen the dimerization energy of adsorbed CO intermediate, thus boosting the conversion of CO2 to produce C2H4. This study provides a new perspective for promoting selective C–C coupling for electrochemical CO2 reduction

Strategies for enhancing electrochemical CO 2 reduction to multi-carbon fuels on copper

Productively harnessing CO2 as a reactant is of practical interest due to addressing the dual pressures of resource sustainability and environmental sustainability. Electrochemical CO2 reduction (ECR) offers a promising approach for driving the chemical transformation of CO2 by exploiting green renewably generated electricity at (near) room temperature and ambient pressure, facilitating a sustainable, low-carbon footprint future. In this work, we provide a comprehensive and timely review of the various avenues that have been developed to date to modulate product selectivity, stability, and efficiency toward C2+ using Cu-based electrocatalysts. We discuss how the electrocatalyst structure can be effectively designed in order to boost performance. Special attention is paid to some of the critical intermediate species that shed light on CO2 reduction paths. We will also discuss the application of in situ and operando spectroscopy, along with computational techniques, that help to improve our fundamental understanding of ECR. Finally, development opportunities and challenge in the conversion of CO2 into multi-carbon fuels by Cu-based electrocatalysts are presented

Control of zeolite microenvironment for propene synthesis from methanol

Optimising the balance between propene selectivity, propene/ethene ratio and catalytic stability and unravelling the explicit mechanism on formation of the first carbon–carbon bond are challenging goals of great importance in state-of-the-art methanol-to-olefin (MTO) research. We report a strategy to finely control the nature of active sites within the pores of commercial MFI-zeolites by incorporating tantalum(V) and aluminium(III) centres into the framework. The resultant TaAlS-1 zeolite exhibits simultaneously remarkable propene selectivity (51%), propene/ethene ratio (8.3) and catalytic stability (>50 h) at full methanol conversion. In situ synchrotron X-ray powder diffraction, X-ray absorption spectroscopy and inelastic neutron scattering coupled with DFT calculations reveal that the first carbon–carbon bond is formed between an activated methanol molecule and a trimethyloxonium intermediate. The unprecedented cooperativity between tantalum(V) and Brønsted acid sites creates an optimal microenvironment for efficient conversion of methanol and thus greatly promotes the application of zeolites in the sustainable manufacturing of light olefins.We thank EPSRC (EP/P011632/1), the Royal Society, National Natural Science Foundation of China (21733011, 21890761, 21673076), and the University of Manchester for funding. We thank EPSRC for funding and the EPSRC National Service for EPR Spectroscopy at Manchester. A.M.S. is supported by a Royal Society Newton International Fellowship. We are grateful to the STFC/ISIS Facility, Oak Ridge National Laboratory (ORNL) and Diamond Light Source (DLS) for access to the beamlines TOSCA/MAPS, VISION and I11/I20, respectively. We acknowledge Dr. L. Keenan for help at I20 beamline (SP23594-1). UK Catalysis Hub is kindly thanked for resources and support provided via our membership of the UK Catalysis Hub Consortium and funded by EPSRC grant: EP/R026939/1, EP/R026815/1, EP/R026645/1, EP/R027129/1 or EP/M013219/1 (biocatalysis). We acknowledge the support of The University of Manchester’s Dalton Cumbrian Facility (DCF), a partner in the National Nuclear User Facility, the EPSRC UK National Ion Beam Centre and the Henry Royce Institute. We recognise Dr. R. Edge and Dr. K. Warren for their assistance during the 60Co γ-irradiation processes. We thank Prof. A. Jentys from the Technical University of Munich for the measurement of the INS spectrum of iso-butene. We thank C. Webb, E. Enston and G. Smith for help with GC–MS; Dr. L. Hughes for help with SEM and EDX; M. Kibble for help at TOSCA/MAPS beamlines. Computing resources (time on the SCARF compute cluster for some of the CASTEP calculations) was provided by STFC’s e-Science facility. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by ORNL. The computing resources at ORNL were made available through the VirtuES and the ICE-MAN projects, funded by Laboratory Directed Research and Development programme and Compute and Data Environment for Science (CADES

Biomass: Renewable carbon resource for chemical and energy industry

International audienceChemistry is indispensable for the elaboration of all products used in everyday life, manufactured goods, materials, fuels and devices for energy, construction, transportation, foods, pharmaceuticals products, personal care products, devices for communication, etc. Considering the wideness of this sector, and its necessary growth for ensuring development and technical progress to an increasing world population, the time has come for a new chemical era in which the environmental impact of chemical products, in terms of hazards, life cycle, carbon footprint and sustainability of resources, is minimized. Utilization of biomass to produce chemicals, energy products, and materials is an important way for sustainable development. This perspective gives a brief overview of the use of biomass as a renewable resource, analyzing its evolution over the years in terms of motives and societal issues, highlighting the seminal contributions and stressing how the remaining challenges will require contributions from all facets of the chemical sciences. Significance and motives of biomass utilization: The green chemistry context This awareness has benefited from concepts and principles established since the 1990's, such as Sheldon's environmental factor, 1 Trost's atom economy, 2 and more globally the Anastas' and Warner's Green Chemistry principles, 3 and Green Carbon Science of He and coworkers. 4 These are now the bases of modern chemistry, ultimately reaching Anastas' Hypocratic Oath for chemistry, swearing that no chemical process or product should result in any harm, in a global vision including scientific, technological, societal, cultural and ethical issues. 5 Among universal sustainable development goals, responsible consumption and production addresses the key issue of starting materials used for the manufacture of chemicals. Biomass includes all molecular and macromolecular compounds arising from vegetables, agricultural products, forestry products, and leftovers, etc. Use of renewable feedstocks, principally biomass, is an important part of green chemistry. At the same time, the principles of green chemistry also guide the whole process of biomass utilization. Using biomass for chemistry cannot be considered as an end in itself, without keeping all other green chemistry principles right. Efficienc

Two-dimensional materials: synthesis and applications in the electro-reduction of carbon dioxide

The emission of CO2 has become an increasingly prominent issue. Electrochemical reduction of CO2 to value-added chemicals provides a promising strategy to mitigate energy shortage and achieve carbon neutrality. Two-dimensional (2D) materials are highly attractive for the fabrication of catalysts owing to their special electronic and geometric properties as well as a multitude of edge active sites. Various 2D materials have been proposed for synthesis and use in the conversion of CO2 to versatile carbonous products. This review presents the latest progress on various 2D materials with a focus on their synthesis and applications in the electrochemical reduction of CO2. Initially, the advantages of 2D materials for CO2 electro-reduction are briefly discussed. Subsequently, common methods for the synthesis of 2D materials and the role of these materials in the electrochemical reduction of CO2 are elaborated. Finally, some perspectives for future investigations of 2D materials for CO2 electro-reduction are proposed

Emerging heterogeneous catalysts for biomass conversion: studies of the reaction mechanism.

From PubMed via Jisc Publications RouterPublication status: epublishThe development of efficient catalysts to break down and convert woody biomass will be a paradigm shift in delivering the global target of sustainable economy and environment the use of cheap, highly abundant, and renewable carbon resources. However, such development is extremely challenging due to the complexity of lignocellulose, and today most biomass is treated simply as waste. The solution lies in the design of multifunctional catalysts that can place effective control on substrate activation and product selectivity. This is, however, severely hindered by the lack of fundamental understanding of (i) the precise role of active sites, and (ii) the catalyst-substrate chemistry that underpins the catalytic activity. Moreover, active sites alone often cannot deliver the desired selectivity of products, and full understanding of the microenvironment of the active sites is urgently needed. Here, we review key recent advances in the study of reaction mechanisms of biomass conversion over emerging heterogeneous catalysts. These insights will inform the design of future catalytic systems showing improved activity and selectivity

Special Topic on Ionic Liquids: Energy, Materials & Environment

Ionic liquids (ILs) are organic salts with low melting points, which have many unusual properties like negligible vapor pressure, good thermal stability, non-flammability, wide liquid range and electrochemical window, and excellent solvation power for both organic and inorganic substances. The unique characteristics of ILs endow them with great potential for applications in different fields including chemical reactions, extraction and separation, material science, renewable energy, environment, and photoelectric transformations. Their properties can be tuned to suit various applications by changing the structures of the cations and/or anions