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CO2 reduction and fixation products ranging from small molecules to biomolecules, are highly diverse in natural systems. Athough various multicarbon products of CO2 reduction were artificially obtained, the C3+ products with various functional groups (e.g., C-N and C=O bonds), especially biomolecules, have never been reported. Herein, we synthesized C3+ amino acids via electrocatalytic reduction from CO2 and NH3 using chiral Cu films (CCFs) as electrodes. Electron microscopy and theoretical calculations suggested that chiral kink sites Cu(653) is the most likely formed on the surface of CCFs fabricated by electrodeposition in the presence of Histidine (His). Serine (Ser), with an enantiomeric excess (ee) greater than 90% is the main component of various amino acids. Experimental and computational data showed that the 3-hydropyruvic acid formation from OCH2CO* is the stereo-determining step in the Ser formation pathway. The Cu(653) was speculated to be restricting the configuration changes of C3+ intermediates to involve a thermodynamically and kinetically favourable formation of enantiomeric Ser.

Conventional separation technologies to separate valuable commodities are energy intensive, consuming 15% of the worldwide energy. Mixed-matrix membranes, combining processable polymers and selective adsorbents, offer the potential to deploy adsorbent distinct separation properties into processable matrix. We report the rational design and construction of a highly efficient, mixed-matrix metal-organic framework membrane based on three interlocked criteria: (i) a fluorinated metal-organic framework, AlFFIVE-1-Ni, as a molecular sieve adsorbent that selectively enhances hydrogen sulfide and carbon dioxide diffusion while excluding methane; (ii) tailoring crystal morphology into nanosheets with maximally exposed (001) facets; and (iii) in-plane alignment of (001) nanosheets in polymer matrix and attainment of [001]-oriented membrane. The membrane demonstrated exceptionally high hydrogen sulfide and carbon dioxide separation from natural gas under practical working conditions. This approach offers great potential to translate other key adsorbents into processable matrix., This research was supported by the King Abdullah University of Science and Technology (KAUST; S.J.D. and M.E.). O.T. acknowledges support from CℏEM, ShanghaiTech University (grant no. EM02161943). A.M. acknowledges support from the Spanish Ministry of Science and Innovation (grant no. RYC2018-024561-I) and the Regional Government of Aragon (grant no. DGA E13_20R).

A precise investigation of NbO has been carried out by advanced electron microscopy combined with powder and single crystal X-ray diffraction (XRD). The structure of pristine NbO has been determined as Pm-3 m space group (SG) with a = 4.211 Å and the positions of Nb and O at the 3c and 3d Wyckoff positions, respectively, which is consistent with previous report based on powder XRD data. Electron beams induced a structural transition, which was investigated and explained by combining electron diffraction and atomic-resolution imaging. The results revealed that the electron beam stimulated both Nb and O atom-migrations within each fcc sublattice, and that the final structure was SG Fm-3 m with a = 4.29 Å, Nb and O at the 4a and 4b with 75 % occupancy and same chemical composition. Antiphase planar defects were discovered in the pristine NbO and related to the structural transformation. Theoretical calculations performed by density functional theory (DFT) supported the experimental conclusions.

Four novel metal-organic frameworks (MOFs) composed of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene (TBAPy4-) or 1,2,4,5-tetrakis(4-carboxlatephenyl)benzene (TCPB4-) linkers with gallium (Ga) or vanadium (V) were synthesized in this work. 3D electron diffraction patterns combined with high-resolution electron microscopy images were employed to investigate the structure of these MOFs. All four MOFs were highly porous with specific Langmuir surface area ranging from ~900 to over ~1800 m2 g-1. The MOFs also showed high uptake of greenhouse gas and especially selective towards SF6 (110 cm3 cm-3, 293 K 1 bar) and CO2 over N2 (or CH4). Sorption kinetics were investigated in detail and the MOF with the highest gas uptake had pore channels with diameters of approx. 9.1 13.6 and 6.5 13.7 in dimension. These Ga- and V-MOFs are potentially interesting candidate sorbents for greenhouse gas capture and separation applications, especially for the separation of SF6 and CO2 from N2, which are relevant in the electronics and chemical industry, respectively.

Two-dimensional conductive metal-organic frameworks (2D

Incorporating hetero-metal-atom, e.g., titanium, into zeolite frameworks can enhance the catalytic activity and selectivity in oxidation reactions. However, the rational design of zeolites containing titanium at specific sites is difficult because the precise atomic structure during synthesis process remained unclear. Here, a titanosilicate with predictable titanium distribution was synthesized by mediating vacancies in a defective MSE-type zeolite precursor, based on a pre-designed synthetic route including modification of vacancies followed by titanium insertion, where electron microscopy (EM) plays a key role at each step resolving the atomic structure. Point defects including vacancies in the precursor and titanium incorporated into the vacancy-related positions have been directly observed. The results provide insights into the role of point defects in zeolites towards the rational synthesis of zeolites with desired microscopic arrangement of catalytically active sites., The authors would like to thank to the Centre for High-resolution Electron Microscopy (CħEM), supported by SPST, ShanghaiTech University (EM02161943); to the National Natural Science Foundation of China (NSFC-21850410448, NSFC-21835002). OT and JY acknowledge the 111 project of China (B17020), AM acknowledges the Spanish Ministry of Science and Innovation (RYC2018-024561-I), to the regional government of Aragon (DGA E13_20R) and to the European Union's Horizon 2020 research and innovation programme under grant agreement No 823717—ESTEEM3. YK is grateful to the Japan Science and Technology Agency (JST) for the CONCERT-Japan (grant number: JPMJSC18C4) program, and to the Japan Society for the Promotion of Science (JSPS) for the Grant-in-Aid for Scientific Research, grant numbers 19H02513 and 22K04825.

Charges on a metal nanoparticle are measured with precision by electron holography

2D conductive metal-organic frameworks (2D c-MOFs) are promising candidates for efficient electrocatalysts for the CO2 reduction reaction (CO2RR). A nitrogen-rich tricycloquinazoline (TQ) based multitopic catechol ligand was used to coordinate with transition-metal ions (Cu2+ and Ni2+), which formed 2D graphene-like porous sheets: M-3(HHTQ)(2) (M=Cu, Ni; HHTQ=2,3,7,8,12,13-Hexahydroxytricycloquinazoline). M-3(HHTQ)(2) can be regarded as a single-atom catalyst where Cu or Ni centers are uniformly distributed in the hexagonal lattices. Cu-3(HHTQ)(2) exhibited superior catalytic activity towards CO2RR in which CH3OH is the sole product. The Faradic efficiency of CH3OH reached up to 53.6 % at a small over-potential of -0.4 V. Cu-3(HHTQ)(2) exhibited larger CO2 adsorption energies and higher activities over the isostructural Ni-3(HHTQ)(2) and the reported archetypical Cu-3(HHTP)(2). There is a strong dependence of both metal centers and the N-rich ligands on the electrocatalytic performance.

l conductivity and chemical/thermal stability. Various applications have also been reported for the phases with different values of n, or slightly reduced rutile (TiO2). The characteristic properties of these materials depend strongly on the compositional deviation from TiO2 and the way in which the structure accommodates the deviation. Thus, an urgent requirement is to overcome difficulties in characterizing such materials at atomic resolution. Here, we trace the discovery of the Andersson‐Magnéli phases, and report the application of recent developments in electron microscopy to reveal the relation, at the local level, between structural characteristics and electronic states, specifically for the materials TinO2n‐1 with n=4–8. The electrical conductivity of Ti4O7 has been reported previously to show three clearly distinct states on decreasing temperature from 300 K. For this reason, we focus on Ti4O7 as a representative example of the TinO2n‐1 phases and report structural characteristics at temperatures corresponding to each of the three different phases, focusing on the distribution of Ti3+ and Ti4+ cations from analysis of single‐crystal XRD data. Electron diffraction experiments and electrical conductivity measurements are also reported.

The development of high-tap density electrode materials that can simultaneously achieve stable electrochemical performance at high charge/discharge rates is critically in demand. Herein, we propose an innovative material design that can offer high tap density and excellent rate capabilities by using Co3O4 nanograin-interconnected secondary particles (Co3O4 NISPs). By taking advantage of a conversion reaction that forms Co from Co3O4, we demonstrate that Co3O4 NISPs are capable of creating a number of metallic Co sites along with a number of vacant sites in-between nanograins. Electrochemical tests that reveal reduced internal cell resistance and more accessible Li diffusion are achieved for Co3O4 NISPs compared with Co3O4 nanoparticles (NPs). Additionally, in situ X-ray diffraction (XRD) analyses, electron energy loss spectroscopy (EELS), and density functional theory (DFT) calculations reveal that the insulating intermediate product (CoO) is formed less on the Co3O4 NISPs, which can enhance the charge transport. Attributed to the combinatorial effects of Co3O4 nanograins that form metallic Co upon conversion and secondary particles that enable high tap density, Co3O4 NISPs show the most outstanding volumetric capacity (2167.3 mA h cm−3 at a current density of 500 mA g−1) among spinel-type metal oxide electrode materials researched so far.

Coronene and its derivatives were synthesized using methanol inside Ca2+ ion-exchanged small-pore zeolites with an 8-membered ring window, such as LTA and RHO zeolites. The polyaromatic hydrocarbon product exhibited white fluorescence under UV light excitation, as characterized by UV-Vis absorption and fluorescence spectra, and fluorescence microscopy images. The formation of coronene and even larger polyaromatics from methanol could be attributed to the fact that Ca2+ ions, unlike the hydroxyl protons of acidic zeolite frameworks, effectively attract the π-electron clouds of benzene rings of small polycyclic intermediates with no disruption of the aromaticity, which leads to the rapid growth of the aromatic ring system. The molecular dimensions of the resultant polyaromatic product were determined by the confined α-cages of the LTA and RHO zeolites. This phenomenon could be extended to CHA zeolite with smaller pore sizes, restricting the molecular growth more severely than in the cases of LTA and RHO zeolites.

Metal–organic frameworks (MOFs)1–3 are known for their specific interactions with gas molecules4,5; this, combined with their rich and ordered porosity, makes them promising candidates for the photocatalytic conversion of gas molecules to useful products6. However, attempts to use MOFs or MOF-based composites for CO2 photoreduction6–13 usually result in far lower CO2 conversion efficiency than that obtained from state-of-the-art solid-state or molecular catalysts14–18, even when facilitated by sacrificial reagents. Here we create ‘molecular compartments’ inside MOF crystals by growing TiO2 inside different pores of a chromium terephthalate-based MOF (MIL-101) and its derivatives. This allows for synergy between the light-absorbing/electron-generating TiO2 units and the catalytic metal clusters in the backbones of MOFs, and therefore facilitates photocatalytic CO2 reduction, concurrent with production of O2. An apparent quantum efficiency for CO2 photoreduction of 11.3 per cent at a wavelength of 350 nanometres is observed in a composite that consists of 42 per cent TiO2 in a MIL-101 derivative, namely, 42%-TiO2-in-MIL-101-Cr-NO2. TiO2 units in one type of compartment in this composite are estimated to be 44 times more active than those in the other type, underlining the role of precise positioning of TiO2 in this system. Investigation of a chromium-based metal–organic framework shows that the location of added TiO2 inside specific mesopores strongly affects the ability of the material to catalyse photoreduction of CO2.

Summary Despite their open and uniformly distributed active sites, the relatively low stability of coordination bonds in metal-organic frameworks (MOFs) limits their applications in catalytic reactions, especially under harsh environments. Here, we report a design of MOF@mesoporous SiO2 yolk-shell nanoreactors via a mesoporous silica coating followed by selective water-etching strategy. Different from conventional alkali- or acid-etching methods, water etching of MOF surface presents a green and cost-effective way to form yolk-shell structures. The yolk-shell nanoreactors exhibit higher catalytic stability than bare MOF crystals in CO2 cycloaddition with product yield remaining unchanged upon three cycles, owing to their permeable mesoporous SiO2 shells, exposed active sites on MOF surfaces, and protective shells. The design concept and synthetic strategy via selective water etching may be used to construct other highly stable MOF-based nanocatalysts, broadening their applications in diverse catalytic reactions.

Zeolites are becoming more versatile in their chemical functions through rational design of their frameworks. Therefore, direct imaging of all atoms at the atomic scale, basic units (Si, Al, and O), heteroatoms in the framework, and extra‐framework cations, is needed. TEM provides local information at the atomic level, but the serious problem of electron‐beam damage needs to be overcome. Herein, all framework atoms, including oxygen and most of the extra‐framework Na cations, are successfully observed in one of the most electron‐beam‐sensitive and lowest framework density zeolites, Na‐LTA. Zeolite performance, for instance in catalysis, is highly dependent on the location of incorporated heteroatoms. Fe single atomic sites in the MFI framework have been imaged for the first time. The approach presented here, combining image analysis, electron diffraction, and DFT calculations, can provide essential structural keys for tuning catalytically active sites at the atomic level., Financial support is acknowledged from CħEM, SPST, ShanghaiTech in the form of grant no. EM02161943 (A.M., Q.Z., Y.M., and O.T.), NFSC‐21850410448 (A.M.), NSFC‐21835002 (A.M., Y.M., J.Y., and O.T.), basic funding of the MPG (P.L., W.S., and F.S.), Foreign 1000 Talents plan, China (O.T.), CityU‐9610369 (H.H.), 111 project of China B17020 (A.M., J.Y., O.T.), and the Alexander von Humboldt foundation (P.L.). A.M. acknowledges the Spanish Ministry of Science and Innovation (Ramon y Cajal Program RYC2018‐024561‐I).

Propane dehydrogenation (PDH) has great potential to meet the increasing global demand for propylene, but the widely used Pt-based catalysts usually suffer from short-term stability and unsatisfactory propylene selectivity. Herein, we develop a ligand-protected direct hydrogen reduction method for encapsulating subnanometer bimetallic Pt-Zn clusters inside silicalite-1 (S-1) zeolite. The introduction of Zn species significantly improved the stability of the Pt clusters and gave a superhigh propylene selectivity of 99.3 % with a weight hourly space velocity (WHSV) of 3.6-54 h-1 and specific activity of propylene formation of 65.5 mol C 3 H 6 gPt -1 h-1 (WHSV=108 h-1 ) at 550 °C. Moreover, no obvious deactivation was observed over PtZn4@S-1-H catalyst even after 13000 min on stream (WHSV=3.6 h-1 ), affording an extremely low deactivation constant of 0.001 h-1 , which is 200 times lower than that of the PtZn4/Al2 O3 counterpart under the same conditions. We also show that the introduction of Cs+ ions into the zeolite can improve the regeneration stability of catalysts, and the catalytic activity kept unchanged after four continuous cycles.

The response of metal–organic frameworks (MOFs) toward external stimuli, such as light, heat, and electrons, usually involves a local change in their structures. Although diffraction methods allow ...

Defects within zeolites are crucially important for explaining their physicochemical behavior. The UTL zeolite, with a pillared layer structure, has been widely used in zeolite crystal engineering to assemble new structures from its layered structural units, but a fundamental understanding of its defect is lacking. Here, we report a newly synthesized UTL framework zeolite, UTL-DBU, with a commercially available superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a template. Its structure was determined by a combination of three-dimensional electron diffraction tomography and high-resolution (scanning) transmission electron microscopy. Using transmission electron microscopy, two types of defects, stacking disorder and edge dislocation-like planar defect, were discovered. On the basis of the analysis of the electron diffraction and imaging, the layer stacking sequence together with the structural and mathematical models of the microtwinning was successfully built up. Unraveling these defects will provide new insights into the rational design of targeted zeolites utilizing UTL.

Chiral mesostructures exhibit distinctive twisting and helical hierarchical stacking ranging from atomic to micrometre scales. A detailed analysis of these materials is key to understanding their characteristic chiral anisotropy. However, the determination of these multilevel chirality remains challenging due to the limited information from spectroscopy, diffraction techniques, scanning electron microscopy and the two-dimensional projections in transmission electron microscopy. Herein, we report a general approach to determine chiral hierarchical mesostructures based on three-dimensional electron diffraction tomography (3D EDT), by which the structure can be solved synchronously according to the quantitative measurement of diffraction spot deformations and their arrangement in reciprocal space. This method was verified on two samples—chiral mesostructured nickel molybdate and chiral mesostructured tin dioxide—revealing hierarchical chiral structures that cannot be determined by conventional techniques. This approach provides more precise and comprehensive identification of the hierarchical mesostructures, which is expected to advance our understanding of structural–chiral anisotropy at the fundamental level.

Atomically dispersed catalysts are a new type of material in the field of catalysis science, yet their large-scale synthesis under mild conditions remains challenging. Here, a general synergistic capture-bonding superassembly strategy to obtain atomically dispersed Pt (Ru, Au, Pd, Ir, and Rh)-based catalysts on micropore-vacancy frameworks at a mild temperature of 60 °C is reported. The precise capture via narrow pores and the stable bonding of vacancies not only simplify the synthesis process of atomically dispersed catalysts but also realize their large-scale preparation at mild temperature. The prepared atomically dispersed Pt-based catalyst possesses a promising electrocatalytic activity for hydrogen evolution, showing an activity (at overpotential of 50 mV) about 21.4 and 20.8 times higher than that of commercial Pt/C catalyst in 1.0 M KOH and 0.5 M H

Hollow nanoparticles featuring tunable structures with spatial and chemical specificity are of fundamental interest. However, it remains a significant challenge to design and synthesize asymmetric nanoparticles with controllable topological hollow architecture. Here, a versatile kinetics-regulated cooperative polymerization induced interfacial selective superassembly strategy is demonstrated to construct a series of asymmetric hollow porous composites (AHPCs) with tunable diameters, architectures and components. The size and number of patches on Janus nanoparticles can be precisely manipulated by the precursor and catalyst content. Notably, AHPCs exhibit excellent photothermal conversion performance under the irradiation of a near infrared (NIR) laser. Thus, AHPCs are utilized as NIR light-triggered nanovehicles and cargos can be controllably released. In brief, this versatile superassembly approach offers a streamlined and powerful toolset to design diverse asymmetric hollow porous composites.

Heterogeneous catalysis of formic acid dehydrogenation at room temperature is a promising tactic for safely storing and producing H2 as an efficient energy carrier. Up to now, the catalysts for thi...

State-of-the-art electron crystallography when combined with geometric techniques to model curved surfaces enables an in-depth study of twinning defects in bicontinuous cubic structures., Bicontinuous cubic structures in soft matter consist of two intertwining labyrinths separated by a partitioning layer. Combining experiments, numerical modelling and techniques in differential geometry, we investigate twinning defects in bicontinuous cubic structures. We first demonstrate that a twin boundary is most likely to occur at a plane that cuts the partitioning layer almost perpendicularly, so that the perturbation caused by twinning remains minimal. This principle can be used as a criterion to identify potential twin boundaries, as demonstrated through detailed investigations of mesoporous silica crystals characterized by diamond and gyroid surfaces. We then discuss that a twin boundary can result from a stacking fault in the arrangement of inter-lamellar attachments at an early stage of structure formation. It is further shown that enhanced curvature fluctuations near the twin boundary would cost energy because of geometrical frustration, which would be eased by a crystal distortion that is experimentally observed.

Efficient production of lactide (LT) from highly concentrated lactic acid (LA) based on β zeolite catalysts is highly desired for an economically sustainable polylactic acid (PLA) industry. Like an...

Surface-sensitive information on a bulk sample can be obtained by using a low incident electron energy (low accelerating voltage/landing voltage) in a scanning electron microscope (SEM). However, topography and composition contrast obtained at low incident electron energies may not be intuitive and should be analyzed carefully. By combining an Auger electron spectrometer (AES) with a low incident electron energy SEM (LE-SEM), we investigated the SEM contrast carefully by separating the secondary electron (SE) and back-scattered electron (BSE) components with high accuracy. For this, we modified an AES to measure the electron energy in the range of 0–0.6 keV with a sample bias voltage of 0 to −0.3 keV. We could clearly observe reversed brightness of gold and carbon (graphite) in BSE images when the energy of the incident electrons was reduced to 0.2–0.3 keV. In addition, reflected electron energy spectroscopy (REELS) is known to be a tool for chemical state analysis of the sample. We demonstrated that it is possible to study the electron states of graphite, diamond, and graphene by acquiring low incident energy REELS spectra from their surfaces with the newly modified AES. This will be a new method for analyzing the electron states of local areas of a surface.

Gas adsorption of periodic mesoporous organosilica (PMO) containing bipyridine ligands within the framework (BPy-PMO) has been studied by in situ gas adsorption powder X-ray diffraction (XRD) analy...

For a better design of adsorbents, it is important to know the intermolecular interaction among adsorbates and host material, leading to improved guest selectivity and uptake capacity. In this study, we demonstrate the influence of the interaction among adsorbates and substrate, controlled by the pore environment and species of adsorbates, on the adsorption behaviour. We report the unique CO2 adsorption behaviour of MOF-205 due to distinct pore geometry. The precise analysis through gas-adsorption crystallography with molecular simulation shows that capillary condensation of CO2 in MOF-205 occurs preferentially in the large dodecahedral pore rather than the small tetrahedral pore, because the interaction of CO2 with MOF-205 framework is weaker than that among CO2 molecules, while Ar and N2 are sequentially filled into two different pores of MOF-205 according to their size. Comparison of the materials with different pore environments reveals that the relative strength of the adsorbate-adsorbate and adsorbate-substrate interaction gives rise to different shapes of isotherms.

Hierarchical nanozeolites are highly desired for heavy oil conversion because of their fast mass transfer, good site accessibility, and short diffusion length compared with their conventional counterparts. Here, we provide a facile amino acid-assisted strategy to synthesize hierarchical ZSM-5 (MFI) zeolite nanocrystals by two-step crystallization in a concentrated gel system. Strikingly, each virus-like zeolite nanoparticle with abundant interconnected intracrystalline mesopores is a high-quality single crystal that is defect-free as confirmed by electron diffraction and NMR analysis. By utilizing advanced electron microscopy techniques, we have studied the evolution process of single-crystalline hierarchical ZSM-5 nanocrystals that involves oriented aggregation of protozeolitic nanoparticles formed at low temperature followed by intraparticle ripening at high temperature. The as-prepared hierarchical Ni@ZSM-5 catalysts exhibit superior catalytic performance in hydrodeoxygenation of stearic acid and palm oil.

Defects within zeolites are crucially important for explaining their physicochemical behavior. The