The unique applications of porous metal–organic framework (MOF) liquids with permanent porosity and fluidity have attracted significant attention. However, fabrication of porous MOF liquids remains ...challenging because of the easy intermolecular self‐filling of the cavity or the rapid settlement of porous hosts in hindered solvents that cannot enter their pores. Herein, we report a facile strategy for the fabrication of a MOF liquid (Im‐UiO‐PL) by surface ionization of an imidazolium‐functionalized framework with a sterically hindered poly(ethylene glycol) sulfonate (PEGS) canopy. The Im‐UiO‐PL obtained in this way has a CO2 adsorption approximately 14 times larger than that of pure PEGS. Distinct from a porous MOF solid counterpart, the stored CO2 in Im‐UiO‐PL can be slowly released and efficiently utilized to synthesize cyclic carbonates in the atmosphere. This is the first example of the use of a porous MOF liquid as a CO2 storage material for catalysis. It offers a new method for the fabrication of unique porous liquid MOFs with functional behaviors in various fields of gas adsorption and catalysis.
An ionization strategy has been developed to fabricate a porous MOF liquid, which shows large adsorption of CO2. The adsorbed CO2 can subsequently be slowly released and efficiently utilized to synthesize, for example, cyclic carbonates.
Covalent organic frameworks (COFs) are promising candidates for electrocatalytic reduction of carbon dioxide into valuable chemicals due to their porous crystalline structures and tunable single ...active sites, but the low conductivity leads to unmet current densities for commercial application. The challenge is to create conductive COFs for highly efficient electrocatalysis of carbon dioxide reduction reaction (CO2RR). Herein, a porphyrin‐based COF containing donor–acceptor (D–A) heterojunctions, termed TT‐Por(Co)‐COF, is constructed from thieno3,2‐bthiophene‐2,5‐dicarbaldehyde (TT) and 5,10,15,20‐tetrakis(4‐aminophenyl)‐porphinatocobalt (Co‐TAPP) via imine condensation reaction. Compared with COF‐366‐Co without TT, TT‐Por(Co)‐COF displays enhanced CO2RR performance to produce CO due to its favorable charge transfer capability from the electron donor TT moieties to the acceptor Co‐porphyrin ring active center. The combination of strong charge transfer properties and enormous amount of accessible active sites in the 2D TT‐Por(Co)‐COF nanosheets results in good catalytic performance with a high Faradaic efficiency of CO (91.4%, −0.6 V vs reversible hydrogen electrode (RHE) and larger partial current density of 7.28 mA cm−2 at −0.7 V versus RHE in aqueous solution. The results demonstrate that integration of D–A heterojunctions in COF can facilitate the intramolecular electron transfer, and generate high current densities for CO2RR.
A donor–acceptor heterojunctions is constructed in cobalt porphyrin‐based COF (TT‐Por(Co)‐COF) to enhance the current density of CO2 electroreduction reaction due to its favorable charge transfer capability. TT‐Por(Co)‐COF nanosheets show a high FECO of 91.4% at −0.6 V versus reversible hydrogen electrode (RHE) and large partial current density of 7.28 mA cm−2 at −0.7 V versus RHE in aqueous solution.
Efficient and economical photocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are required to replace expensive metal-based catalysts used in water ...splitting devices. Herein, we have developed an inexpensive route to synthesize a carbon-rich graphitic carbon nitride (C-rich g-C 3 N 4 ) with both nitrogen vacancies and a porous structure, which, as a highly efficient photo-induced water splitting catalyst, can meet current demands. The effects of the porous structure, nitrogen vacancies and rich amount of carbon on the electronic band structure and charge transport of g-C 3 N 4 are systematically elucidated. The C-rich g-C 3 N 4 can not only effectively enhance the absorption of visible light, but can also improve the majority carrier mobility and promote photoelectron transport through the defect-induced mid-gap and multiple conductive carbon rings, thus synergistically elongating the diffusion length and lifetime of the photocarriers. Importantly, the metal-free C-rich g-C 3 N 4 photocatalyst not only demonstrates a higher solar-driven hydrogen production performance, which is over 20.5 times that of pristine g-C 3 N 4 , but also exhibits an outstanding stability with minimal loss of catalytic activity.
We present the first example of charged imidazolium functionalized porphyrin‐based covalent organic framework (Co‐iBFBim‐COF‐X) for electrocatalytic CO2 reduction reaction, where the free anions ...(e.g., F−, Cl−, Br−, and I−) of imidazolium ions nearby the active Co sites can stabilize the key intermediate *COOH and inhibit hydrogen evolution reaction. Thus, Co‐iBFBim‐COF‐X exhibits higher activity than the neutral Co‐BFBim‐COF, following the trend of F−<Cl−<Br−<I−. Particularly, the Co‐iBFBim‐COF‐I− showed nearly 100 % CO2 selectivity at a low full‐cell voltage of 2.3 V, and achieved a high CO2 partial current density of 52 mA cm−2 with a turnover frequency of 3018 h−1 at 2.4 V in the anion membrane electrode assembly, which is 3.57 times larger than that of neutral Co‐BFBim‐COF. This work provides new insight into the importance of free anions in the stabilization of intermediates and decreasing the local binding energy of H2O with active moiety to enhance CO2 reduction reaction.
Charged imidazolium struts were integrated into two‐dimensional cobalt porphyrin‐based covalent organic frameworks (Co‐iBFBim‐COF‐X) creating catalytic pockets with 5,10,15,20‐tetrakis(4‐aminophenyl)‐porphinatocobalt centers and halogen counter ions (e.g., F−, Cl−, Br−, and I−). The free imidazolium anions in the proximity of the active Co sites in the Co‐iBFBim‐COF‐X can stabilize the key intermediate *COOH and inhibit the occurrence of HER through hydrogen bonding.
The essential amino acid tryptophan is not only a precursor of serotonin but is also degraded to several other neuroactive compounds, including kynurenic acid, 3-hydroxykynurenine and quinolinic ...acid. The synthesis of these metabolites is regulated by an enzymatic cascade, known as the kynurenine pathway, that is tightly controlled by the immune system. Dysregulation of this pathway, resulting in hyper-or hypofunction of active metabolites, is associated with neurodegenerative and other neurological disorders, as well as with psychiatric diseases such as depression and schizophrenia. With recently developed pharmacological agents, it is now possible to restore metabolic equilibrium and envisage novel therapeutic interventions.
A comprehensive review on the five levels of hierarchical structures of silk materials and the correlation with macroscopic properties/performance of the silk materials, that is, the toughness, ...strain‐stiffening, etc., is presented. It follows that the crystalline binding force turns out to be very important in the stabilization of silk materials, while the β‐crystallite networks or nanofibrils and the interactions among helical nanofibrils are two of the most essential structural elements, which to a large extent determine the macroscopic performance of various forms of silk materials. In this context, the characteristic structural factors such as the orientation, size, and density of β‐crystallites are very crucial. It is revealed that the formation of these structural elements is mainly controlled by the intermolecular nucleation of β‐crystallites. Consequently, the rational design and reconstruction of silk materials can be implemented by controlling the molecular nucleation via applying sheering force and seeding (i.e., with carbon nanotubes). In general, the knowledge of the correlation between hierarchical structures and performance provides an understanding of the structural reasons behind the fascinating behaviors of silk materials.
This review presents five levels of hierarchical structures associated with the mechanical performance of silk materials. The crystallization mechanism concerning how silk fibroin molecules self‐organize into crystallites and crystal networks is highlighted, which allows for rational design and sheds light on mesoscopic reconstruction and mesoscopic engineering for synthesizing mechanically enhanced silk materials.
We propose an effective highest occupied d‐orbital modulation strategy engendered by breaking the coordination symmetry of sites in the atomically precise Cu nanocluster (NC) to switch the product of ...CO2 electroreduction from HCOOH/CO to higher‐valued hydrocarbons. An atomically well‐defined Cu6 NC with symmetry‐broken Cu−S2N1 active sites (named Cu6(MBD)6, MBD=2‐mercaptobenzimidazole) was designed and synthesized by a judicious choice of ligand containing both S and N coordination atoms. Different from the previously reported high HCOOH selectivity of Cu NCs with Cu−S3 sites, the Cu6(MBD)6 with Cu−S2N1 coordination structure shows a high Faradaic efficiency toward hydrocarbons of 65.5 % at −1.4 V versus the reversible hydrogen electrode (including 42.5 % CH4 and 23 % C2H4), with the hydrocarbons partial current density of −183.4 mA cm−2. Theoretical calculations reveal that the symmetry‐broken Cu−S2N1 sites can rearrange the Cu 3d orbitals with
dx2-y2
${d_{x^2 - y^2 } }$
as the highest occupied d‐orbital, thus favoring the generation of key intermediate *COOH instead of *OCHO to favor *CO formation, followed by hydrogenation and/or C−C coupling to produce hydrocarbons. This is the first attempt to regulate the coordination mode of Cu atom in Cu NCs for hydrocarbons generation, and provides new inspiration for designing atomically precise NCs for efficient CO2RR towards highly‐valued products.
Breaking the coordination symmetry of Cu site in atomically precise Cu6 cluster forms Cu‐S2N1 site, which rank the dx2‐y2 orbital as the highest occupied d orbital to favor the specific coordination between C atom of CO2 and Cu−S2N1 site. This binding mode is conductive to the generation of *COOH instead of *OCHO, thereby switching the product of electrocatalytic CO2 reduction reaction to higher‐valued hydrocarbons.
Due to the natural biodegradability and biocompatibility, silk fibroin (SF) is one of the ideal platforms for on‐skin and implantable electronic devices. However, the development of SF‐based ...electronics is still at a preliminary stage due to the SF film intrinsic brittleness as well as the solubility in water, which prevent the fabrication of SF‐based electronics through traditional techniques. In this article, a flexible and stretchable silver nanofibers (Ag NFs)/SF based electrode is synthesized through water‐free procedures, which demonstrates outstanding performance, i.e., low sheet resistance (10.5 Ω sq−1), high transmittance (>90%), excellent stability even after bending cycles >2200 times, and good extensibility (>60% stretching). In addition, on the basis of such advanced (Ag NFs)/SF electrode, a flexible and tactile sensor is further fabricated, which can simultaneously detect pressure and strain signals with a large monitoring window (35 Pa–700 kPa). Besides, this sensor is air‐permeable and inflammation‐free, so that it can be directly laminated onto human skins for long‐term health monitoring. Considering the biodegradable and skin‐comfortable features, this sensor may become promising to find potential applications in on‐skin or implantable health‐monitoring devices.
A biodegradable and stretchable protein‐based sensor with good biocompatibility and high response time is fabricated. It can be used for the human motion detection, such as arm bending and laryngeal movement.
The fall armyworm (FAW), Spodoptera frugiperda is one of the most damaging crop pests, and it has become major threat to the food security of many countries. In order to monitor possible invasion of ...this pest into China, a searchlight trap was established in March 2018 in western Yunnan Province, China, where it has served as the “first station” for many pests that have migrated from Myanmar to China. A number of suspected FAW moths were captured and identified by DNA sequencing. The results showed that the FAW moth was first captured on December 11 and formed its first immigration peak in mid-December 2018. DNA detection revealed that the early invading FAW population was the “corn-strain”. The field survey indicated that the pest mainly colonized corn in Pu'er, Dehong and Baoshan areas. Migration trajectory simulation implied that the moths might have mainly come from the eastern area in the mid-latitude region of Myanmar (20–25°N, 94–100°E). This case study confirmed the first immigration of FAW into China, and will be helpful for guiding monitoring and management work to control this pest.
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