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Nondoped organic light-emitting diodes (OLEDs) are of paramount importance for display and lighting applications owing to their advantages of facile fabrication and outstanding stability. However, nondoped OLEDs achieving extraordinary electroluminescence (EL) performance and low turn-on voltage (

Herein, a N-rich metal-organic framework (MOF) with four kinds of cages, Zn

Constructing high-quality white organic light-emitting diodes (WOLEDs) remains a big challenge because of high demands on the electroluminescence (EL) performance including high efficiency, excellent spectral stability, and low roll-off simultaneously. To achieve effective energy transfer and trap-assisted recombination in the emissive layer, herein, four Ir(III) phosphors, namely

Polyoxometalates (POMs) have a broad array of applied platforms with well-characterized catalysis including photocatalysis to achieve aliphatic C(sp3)-H bond functionalization. However, the reaction mechanism of POMs in organic transformation remains unknown due to the complexity of POM structures. Here, a challenging [W10O32]4-/Ni metallaphotoredox-catalyzed C(sp3)-H arylation of alkane has been investigated by density functional theory (DFT) calculations. The calculation revealed that the superficial active center located in bridged oxygen of *[W10O32]4- is responsible for the abstraction of a foreign hydrogen atom and the activation of a C(sp3)-H bond. Furthermore, we discussed this activated process using the direct activation model of the C(sp3)-H σ-bond to deepen our mechanistic understanding of POM mediated C-H bond activation via the hydrogen atom transfer (HAT) pathway. Specifically, comparing three common mechanisms for nickel catalysis inducing by Ni0, NiI, and NiII to construct a C-C bond, the nickel catalytic cycle induced by the NiI active catalyst is profitable in kinetics and thermodynamics. Finally, a radical mechanism merging the ([W10O32]4--*[W10O32]4--[HW10O32]4--[W10O32]4-) decatungstate reductive quenching cycle, ([HW10O32]4--[H2W10O32]4--[HW10O32]4-) electron relay, and (NiI-NiII-NiI-NiIII-NiI) nickel catalytic cycle is proposed to be favorable. We hope that this work would provide a better understanding of the unique catalytic activity of decatungstate anions for the direct functionalization of the C(sp3)-H bond.

Lead halide perovskites (LHPs) with excellent performance have become promising materials for optoelectrical devices. However, as for the dual-color emission LHPs (DELHPs), the low photoluminescence quantum yield (PLQY) hinders their applications. Herein, a simple low-cost room-temperature post-synthetic modification strategy is used to achieve a near-unity PLQY of DELHPs. It is proven that ZnBr2 plays an important role as an inorganic ligand in reducing surface defects to induce a 95.4% increase in the radiative decay rate and a 99.5% decrease in the nonradiative decay rate in the treated DELHPs compared with the pristine DELHPs. The performance of the blue emission from the surface lattice is greatly improved via the modification of ZnBr2. DELHPs with different ratios of blue and green emissions are obtained by changing the specific surface area and ZnBr2 concentration. The distribution and mechanism of Zn2+ are discussed using the research model based on these DELHPs. The first example of the single-layer dual-color perovskite electroluminescence device is realized from DELHPs. This work provides a new perspective for improving the performance of DELHPs, which will greatly accelerate the development of emission materials of LHPs.

Photocatalytic carbon dioxide reduction (CO2RR) is considered to be a promising sustainable and clean approach to solve environmental issues. Polyoxometalates (POMs), with advantages in fast, reversible, and stepwise multiple-electron transfer without changing their structures, have been promising catalysts in various redox reactions. However, their performance is often restricted by poor thermal or chemical stability. In this work, two transition-metal-modified vanadoborate clusters, [Co(en)2]6[V12B18O54(OH)6]·17H2O (V12B18-Co) and [Ni(en)2]6[V12B18O54(OH)6]·17H2O (V12B18-Ni), are reported for photocatalytic CO2 reduction. V12B18-Co and V12B18-Ni can preserve their structures to 200 and 250 °C, respectively, and remain stable in polar organic solvents and a wide range of pH solutions. Under visible-light irradiation, CO2 can be converted into syngas and HCOO- with V12B18-Co or V12B18-Ni as catalysts. The total amount of gaseous products and liquid products for V12B18-Co is up to 9.5 and 0.168 mmol g-1 h-1. Comparing with V12B18-Co, the yield of CO for V12B18-Ni declines by 1.8-fold, while that of HCOO- increases by 35%. The AQY of V12B18-Co and V12B18-Ni is 1.1% and 0.93%, respectively. These values are higher than most of the reported POM materials under similar conditions. The density functional theory (DFT) calculations illuminate the active site of CO2RR and the reduction mechanism. This work provides new insights into the design of stable, high-performance, and low-cost photocatalysts for CO2 reduction.

The solid-solid conversion of Li2S2 to Li2S is a crucial and rate-controlling step that provides one-half of the theoretical capacity of lithium-sulfur (Li-S) batteries. The catalysts in the Li-S batteries are often useless in the solid-solid conversion due to the poor contact interfaces between solid catalysts and insoluble solid Li2S2. Considering that ultrafine nanostructured materials have the properties of quantum size effects and unconventional reactivities, we design and synthesize for the pomegranate-like sulfur nanoclusters@nitrogen-doped carbon@nitrogen-doped carbon nanospheres (S@N-C@N-C NSs) with a seed-pulp-peel nanostructure. The ultrafine S@N-C subunits (diameter ≈5 nm) and effects of a spatial structure perfectly realize the rapid conversion of ultrafine Li2S2 to Li2S. The S@N-C@N-C seed-pulp-peel NS cathodes exhibit excellent sulfur utilization, superb rate performance (760 mAh g-1 at 10.0 C), and an ultralow capacity decay rate of about 0.016% per cycle over 1000 cycles at 4.0 C. The proposed strategy based on ultrafine nanostructured materials can also inform material engineering in related energy storage and conversion fields.

For the electrochemical reduction of CO2, CO is a crucial single-carbon product and a major intermediate to multicarbon products. Direct dimerization of CO is the most charming channel to C2 products, although the corresponding kinetic energy barrier causes a huge gap compared with other alternative pathways. The effective CO migration among multiple catalytic sites is predominant but has not been fully explored during the C-C bond formation and further protonation processes. Herein, the entirely planar global-minimum Ni2B5 monolayer with multikinds of catalytic sites is selected as an appropriate instance, on which CO can effectively migrate among different types of sites with the highest barrier of 0.64 eV. Most importantly, the computed ultralow barrier of direct *CO dimerization (0.17 eV), the limiting potentials for CH2CH2 (-0.13 V), and CH3CH2OH (-0.17 V) reach the optimal value until now, which all happen on the p-p type of dual-CO adsorption configurations after CO migration. Moreover, the hydrogen reduction side reaction is uncompetitive with the CO electrochemical reduction on all possible adsorption sites. This study demonstrates the significance of CO migration and opens a new avenue for CO reduction to high-density multicarbon products on the surface of catalysts possessing multikinds of catalytic sites.

Recent experimental work reported that visible-light photoredox catalysis coupled with primary sulfonamides and electron-deficient alkenes could efficiently construct C-C bonds at the α-position of primary amine derivatives under mild conditions. Here, a systematic study was conducted to explore the non-negligible excited-state single-electron-transfer (SET) processes and the catalytic cycle. Hydrogen atom transfer (HAT) catalysis containing different site-selective functionalization, involved as a critical process during the reaction, was computationally characterized. The superiorities of iridium-based photoredox catalysts in terms of photoabsorption properties, phosphorescence rates, and electron-transfer rates for SET processes were focused on. In addition, the function of quinuclidine in the entire photocatalytic reaction was also probed. These intrinsic properties and detailed insights into the mechanism are supposed to be helpful to the understanding of the C-C bond functionalization reaction and the future application of the iridium-based photoredox catalyst.

The search for highly stable hydrogen evolution reaction (HER) catalysts with high activity, multiple active sites, and excellent electrical conductivity is crucial to promote the development of hy...

Phosphorescent organic light-emitting diodes (OLEDs) with high electroluminescence (EL) efficiency and low efficiency roll-off are urgently required to meet the continuously increasing market need ...

The lithium-sulfur battery is a promising high-energy-density storage system, which suffers from severe capacity fading due to the "shuttle effect" and low Coulombic efficiency caused by the dissolution of lithium polysulfides. At the molecular level, suppressing the shuttle effect has been greatly required for high-performance Li-S batteries. Herein, we propose a new strategy by utilizing a protonated organic absorbent (N1,N4-bis(pyridine-3-ylmethyl)butane-1,4-diammonium nitrate ([H2PBD]2+·(NO3)22-) for ultrafast absorption of polysulfides through electrostatic attractions and for fixing the polysulfides in the cathode by hydrogen-bond interactions. A lithium-sulfur battery cathode based on a commercial carbon black (CB) and an absorbent (10%) with high sulfur content (70%) exhibits a low capacity decay of 0.099% per cycle over 400 cycles at a rate of 0.5C along with 91% Coulombic efficiency. This strategy and the finding of an electrostatic absorbent offer a new alternative insight into designing cheaper lithium-sulfur batteries for their practical application in the future.

Many interesting multifunctional materials are obtained under the application of an external electric field, which arouses extensive interest of experimental and theoretical researchers. In the pre...

Developing highly stable materials for harmful ion detection in a water environment is of much importance and challenging. Here, two three-dimensional porous structures (termed as Eu-MOF and Tb-MOF) were successfully constructed by the strategy of anchoring Eu3+/Tb3+ and rigid 1,2,4,5-benzenetetracarboxylic acid (H4BTEC) imidazole units (H3ICA) onto its frameworks. The obtained Eu-MOF and Tb-MOF display high water stability and fluorescence stability up to 30 days. Furthermore, luminescent studies reveal that Eu-MOF and Tb-MOF show rapid, recursive, and simultaneous sensing Fe3+ and Cr2O72-/CrO42- ions in water. In addition, the sensing function possesses remarkable cyclicity and selectivity even with the existence of other analogous ions.

The performance of MnII/III-monosubstituted heteropolytungstates [MnIII(H2O)GeW11O39]5– ([GT-MnIII-OH2]5–, where GT = GeW11O39) and [MnII(H2O)GeW11O39]6– ([GT-MnII-OH2]6–) as water oxidation catalysts at pH 9 was explored using density functional theory calculations. The counterion effect was fully considered, in which five and six Na+ ions were included in the calculations for water oxidation catalyzed by [GT-MnIII-OH2]5– and [GT-MnII-OH2]6–, respectively. The process of water oxidation catalysis was divided into three elemental stages: (i) oxidative activation, (ii) O–O bond formation, and (iii) O2 evolution. In the oxidative activation stage, two electrons and two protons are removed from [Na5-GT-MnIII-OH2] and three electrons and two protons are removed from [Na6-GT-MnII-OH2]. Therefore, the MnIV-O• species [Na5-GT-MnIV-O•] is obtained. Two mechanisms, (i) water nucleophilic attack and (ii) oxo–oxo coupling, were demonstrated to be competitive in O–O bond formation triggered from [Na5-GT-MnIV-O•]. In ...

Poly(3-hexylthiophene) (P3HT)-based organic solar cells (OSCs) have been developed in recent years because of their advantages such as easy production, low cost, and large-area manufacture. However...

Single-ionic conducting electrolytes are important for the improvement of lithium metal batteries with high energy density and safety. Herein, we propose a new strategy to anchor a large anionic group on the skeleton of metal-organic frameworks (MOFs) and achieve preeminent single-ionic conducting electrolytes. Utilizing a postsynthetic modification method, the trifluoromethanesulfonyl group is covalently coordinated to the amino groups of the UiO-66-NH2 framework. Such a single-ionic conducting solid-state electrolyte (SSE) has a high ionic conductivity (2.07 × 10-4 S cm-1 at 25 °C), a low activation energy of 0.31 eV, a wide electrochemical window up to 4.52 V, as well as a high Li+ transference number of 0.84. Simultaneously, it can effectively inhibit the formation of lithium dendrite. Solid-state batteries assembled with LiFePO4 as the cathode exhibit outstanding rate performance and cyclic stability, especially for low-temperature Li-metal batteries at 0 °C with trace amounts of propylene carbonate as wetting agents. More importantly, the corresponding all-solid-state batteries based on an MOF-based SSE also have nearly 100% Coulombic efficiency at different current densities.

Recently, solution-processable PhOLEDs have been attracting great interest for their low cost and high productivity relative to the vacuum-deposited devices. Similar to vacuum-deposited OLEDs, however, they usually suffer from serious efficiency roll-offs, especially in high brightness. Finding a feasible way and/or designing novel materials to increase efficiencies and reduce roll-offs simultaneously are highly desired. Herein, a new family of solution-processable cyclometalated iridium(III) phosphors with carbazole (

The improvement of the photocatalytic performance of cobaltporphyrin as CO2 reduction catalysts by chemical modification has become a current research hotspot. Here, we contrastively investigate th...

When one is trying to maintain original advantageous properties of molecule without increasing the difficulty of synthesis and processing, simultaneously, adding more predictable properties is a pr...

Photoredox-mediated iridium/nickel dual catalysis has successfully triggered a series of traditionally challenging carbon–heteroatom cross-coupling reactions. However, detailed mechanisms, such as ...

Organic solar cells (OSCs) have made rapid advances in power conversion efficiency during the past decades, which is boosted partly by the various designs of new materials, especially in donor mate...

Nanoscale regular polyhedra with icosahedral symmetry exist naturally as exemplified by virus capsids and fullerenes. Nevertheless, their generation by supramolecular chemistry through the linking of 5-fold symmetry vertices remains unmet because of the absence of 5-fold symmetry building blocks with the requisite geometric features. This situation contrasts with that of tetrahedral and octahedral symmetry metal–organic polyhedra (MOPs), for which appropriate triangular and square molecular building blocks (MBBs) that can serve as vertices or faces are readily available. Herein, we report isolation of a pentagonal [WV5O11(SO4)6]8– cluster and reveal its utility to afford the first four examples of nanoscale Goldberg MOPs, based upon 5-fold MBBs. Two 32-faced Gv(1,1) MOPs and two 42-faced Gv(2,0) MOPs were formed using linear or triangular organic ligands, respectively. The largest Goldberg MOP-4, exhibits a diameter of 4.3 nm, can trap fullerene C60 molecules in its interstitial cavities.

In contrast to the traditional view that the small organic molecules emit fluorescence, more and more experiments manifest their special luminescence types, such as the thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence. Why the similar organic molecules exhibit different luminescence types is focused on in this work on the basis of density functional theory/time-dependent density functional theory calculations on a series of small organic molecules with phenoxazine or carbazole as a donor and diphenyl-triazine as an acceptor. The deep analysis of the geometrical and electronic structures shows how the structure, especially for the donor–acceptor dihedral angle, determines the singlet–triplet energy gap and the property of excited states. The explorations on the electron–hole pairs of natural transition orbitals and the contribution of the key heteroatom (N) to different molecular orbitals reveal the distinct electron transition processes of excitation to singlet and trip...

Rational design of highly efficient electrocatalysts for oxygen evolution reaction (OER) is critical for both water splitting and rechargeable metal–air batteries. Especially, developing excellent earth-abundant catalysts for OER is an ongoing challenge. We report a series of cobalt nitride (Co2N0.67)–carbon composites with different textural properties as high-activity OER materials herein. Experimental results demonstrate that the specific morphologies of different carbon matrices (such as carbon nanotubes (CNTs), graphene (GN), macroporous carbons (MPCs), and hollow carbon microfibers (CMFs)) play crucial roles in determining the overall OER catalytic efficacies of corresponding composites. Both SEM and TEM characterization results revealed that monodisperse and tiny Co2N0.67 nanoparticles (NPs) indeed grew uniformly over both the inner and outer walls of CMFs because of the widespread edges and defect sites. This is beneficial to fully expose and utilize active sites on each Co2N0.67 NP. In addition, ...

The cooperative mechanism of Ni(0)/Lewis acid catalyzed carbocyanation of alkyne with 2,3,5,6-tetrafluorobenzonitrile was investigated using the DFT method. Our calculations indicate that the most feasible catalytic cycle consists of the oxidative addition of a C–CN bond to the Ni(0) center, alkyne insertion into the C(aryl)–Ni(II) bond, and reductive elimination. Notably, the Lewis acid (LA) interacting with the cyano nitrogen atom of the substrate can have a significant effect on activating the C–CN bond while suppressing C–H and C–F bond activations. The origin of lower C–CN activation barrier in the presence of LA can be attributed to the remarkably enhanced charge transfer (CT) amount from the Nicat 3d orbital to C-CN σ* + π* antibonding molecular orbital and the little decrease of interaction energy between Ni-catalyst and substrate. In the C–F and C–H bond activations in the presence of LA, on the contrary, the significant decrease of interaction energy between Ni-catalyst and substrate and almost ...

Flexible Li–S batteries have great potential for next-generation energy storage which can meet the rising demand of rollable displays and wearable electronic devices because of the high theoretical...

Multifunctional nanoparticles (NPs) simultaneously having functions of multimodal therapy and imaging are highly needed in biomedical applications. A unique monstera flower-like gold nanorod/polydopamine bowl (GNR/PDA bowl) with spadix-bract nanostructure was fabricated by a novel and facile approach. The possible formation mechanism of the GNR/PDA bowl spadix-bract NPs was proposed by monitoring the synthetic process. The obtained monstera flower-like GNR/PDA bowl spadix-bract NPs were further selectively functionalized with 1-dodecanethiol (DT) on GNR domains (spadix) to achieve efficient hydrophobic drug delivery capability; meanwhile, the PDA bowl (bract) can load the hydrophilic anticancer drug doxorubicin (DOX). The resultant monstera flower-like DT-GNR/PDA bowl spadix-bract NPs possess an excellent biocompatibility, high dual-drug-loading contents, excellent photothermal conversion efficiency, strong near-infrared (NIR) absorbance, effective attenuation of X-rays, and pH/NIR dual-responsive propert...

With expanding human needs, many heavy metals were mined, smelted, processed, and manufactured for commercialization, which caused serious environmental pollutions. Currently, many adsorption materials are applied in the field of adsorption of heavy metals. Among them, the principle of many mercury adsorbents is based on the interaction between mercury and sulfur. Here, a S-containing metal-organic framework NENU-400 was synthesized for effective mercury extraction. Unfortunately, the skeleton of NENU-400 collapsed easily when exposed to the mercury liquid solution. To improve the stability, a synthetic strategy installing molecular building blocks (MBBs) into the channels was used. Modified by the MBBs, a more stable nanoporous framework was synthesized, which not only exhibits a high capacity of saturation mercury uptake but also shows high selectivity and efficient recyclability.

Developing a high-performance, low-cost, and safer rechargeable battery is a primary challenge in next-generation electrochemical energy storage. In this work, a quasi-solid-state (QSS) sodium-ion full battery (SIFB) is designed and fabricated. Hard carbon cloth derived from cotton cloth and Na3V2(PO4)2O2F (NVPOF) are employed as the anode and the cathode, respectively, and a sodium ion-conducting gel-polymer membrane is used as both the QSS electrolyte and separator, accomplishing the high energy and power densities in the QSS sodium-ion batteries. The energy density can reach 460 W h kg–1 according to the mass of the cathode materials. Moreover, the fabricated QSS SIFB also exhibits an excellent rate performance (e.g., about 78.1 mA h g–1 specific capacity at 10 C) and a superior cycle performance (e.g., ∼90% capacity retention after 500 cycles at 10 C). These results show that the developed QSS SIFB is a hopeful candidate for large-scale energy storage.

Graphitic carbon nitride (g-C3N4) can be used as a photocatalyst to reduce CO2. Doping is an efficient strategy for improving the photocatalytic activity and tuning the electronic structure of g-C3N4. The sulfur-doped g-C3N4 (S-doped g-C3N4) as a promising photocatalyst for CO2 reduction was investigated by density functional theory methods. The electronic and optical properties indicate that doping S enhances the catalytic performance of g-C3N4. From the reduction Gibbs free energies, the optimal path for CO2 reduction reaction to CH3OH production catalyzed by S-doped g-C3N4 is CO2 → COOH* → CO → HCO* → HCHO → CH3O* → CH3OH. In comparison with g-C3N4, doping S can alter the rate-determining step and reduce the Gibbs free energy from 1.43 to 1.15 eV. CO2 reduction activity of S-doped g-C3N4 is better than that of g-C3N4, which is in well agreement with the experimental results. Our work provides useful insights into designing nonmetal-doped g-C3N4 for photocatalytic CO2 reduction reactions.

The highly selective nickel(0)-catalyzed cyanoesterification of cyanoformates with alkynes is greatly facilitated by Lewis acid (LA). We report density functional theory (DFT) investigations on the mechanistic details and provide a rational explanation of the “LA effect”. Our calculations disclose that an unusual biphosphine cycle including rate-determining oxidative addition of a C–CN bond, alkyne migratory insertion, and reductive elimination steps is more favorable than the generally accepted monophosphine cycle. The LA has a non-negligible impact on the mechanistic origin of selective C–CN bond activation. Furthermore, the presence of LA dramatically accelerates alkyne migratory insertion because the strong electron-withdrawing property of LA strengthens the coordination ability of the Ni center with alkyne to form the thermodynamically favorable five-coordinate nickel(II) cyanide carboxylate species, which then avoids the large deformation of the transition state of alkyne migration insertion to give...

Based on s-indaceno[1,2,3-cd;5,6,7-c′d′]diphenalene (1) consisting of two phenalenyl moieties, the monomer 2 and its dimer 22 are designed by boron and nitrogen atoms substituting the central carbon atoms of phenalenyl moieties. Calculated energy decompose analysis (EDA) shows that the orbital interaction for 22 possesses a large attractive contribution of −18.31 kcal mol–1, which is dominated by the π–π stacking interaction between the upper and the lower π-conjugated units. Interestingly, the natural population analysis (NPA) charge and the transition density matrix (TDM) show that both intramolecular charge transfer and intermolecular charge transfer (CT) exist in 22. Further, the first hyperpolarizability (βtot = 4.56 × 104 au) of 2 with intramolecular CT is greatly larger than that of reported molecule 3 (5.45 × 103 au) with intermolecular CT. Significantly, 22 exhibits the largest βtot value to be 1.42 × 105 au, which is caused by combining the intra- and intermolecular CT transitions (βx = 1.40 × 1...

The introduction of the Li3O and BeF3 can exhibit an interlayer charge-transfer transition character for pure phenalenyl (PLY) dimer. A considerable question emerged: Can we modulate the interlayer charge-transfer transition character with different superalkalis and superhalogens? In the present work, nine complexes were designed with three superalkalis (Li3O, Li3S, and Na3O) and three superhalogens (BeF3, BeCl3, and MgF3) introduced into the PLY dimers, respectively. Results showed that the geometric structure, interlayer charge transfer, and electron transition character of PLY dimer were alternated by the superalkalis and superhalogens, especially for superalkali, with the increasing atomic number for alkali metals, interlayer distance and interaction energy between PLY monomers increased, while first hyperpolarizability (βtot) decreased. The results of TD-DFT calculation indicated that the variation of βtot was mainly caused by the alteration of the difference of the dipole moments between the ground ...

Geometrical structures, metal-support interactions, and infrared (IR) spectroscopy of a series of M1/POM (M = Cu, Zn, Ag, and Au; POM = [PW12O40]3-) single-atom catalysts (SACs), and catalytic cycle for alkene epoxidation catalyzed by M1/POM SACs were studied using density functional theory (DFT) calculations. The calculations demonstrate that the most probable anchoring sties for the isolated single atoms studied here in the M1/POM SACs are the fourfold hollow sites on the surface of POM support. The bonding interaction between single metal atom and surface of POM support comes from the molecular orbitals with a mixture of d atomic orbital of metal and 2p group orbital of surface oxygen atoms of POM cage. The calculated adsorption energy of isolated metal atoms in these M1/POM SACs indicates that the early transition metals (Cu and Zn) have high thermal stability. The DFT-derived IR spectra show that the four characteristic peaks of free Keggin-type POM structure split into six because of introduction of isolated metal atom. Compared with other metal atoms, the Zn1/POM SAC has the high reactivity for activity of dioxygen molecule, because the dioxygen moiety in Zn1/POM SAC displays O2-· radical feature with [POM4-·Zn2+O2-·]3- configuration. Finally, a catalytic cycle for ethylene epoxidation by O2 catalyzed by Zn1/POM SAC was proposed based on our DFT calculations. Supported noble-metal SACs are among the most important catalysts currently. However, noble metals are expensive and of limited supply. Development of non-noble-metal SACs is of essential importance. Therefore, the reported Zn1/POM SAC would be very useful to guide the search for SACs into non-noble metals.

Developing a photocatalysis system for converting CO2 to valuable fuels or chemicals is a promising strategy to address global warming and fossil fuel consumption. Exploring photocatalysts with high-performance and low-cost has been two ultimate goals toward photoreduction of CO2. Herein, noble-metal-free polyoxometalates (Co4) with oxidative ability was first introduced into g-C3N4 resulted in inexpensive hybrid materials (Co4@g-C3N4) with staggered band alignment. The staggered composited materials show a higher activity of CO2 reduction than bare g-C3N4. An optimized Co4@g-C3N4 hybrid sample exhibited a high yield (107 μmol g–1 h–1) under visible-light irradiation (λ ≥ 420 nm), meanwhile maintaining high selectivity for CO production (94%). After 10 h of irradiation, the production of CO reached 896 μmol g–1. Mechanistic studies revealed the introduction of Co4 not only facilitate the charge transfer of g-C3N4 but greatly increased the surface catalytic oxidative ability. This work creatively combined ...

Phenalenyl π-dimer (PLY2) has recently attracted intensive research interest due to its unique structure and binding characteristics (two-electron/12-center bonding). The directional transfer of electron or electron pair under the external electric field can produce a new structure with interesting properties. In the present work, we investigate for the first time the effect of the external electric field along the main molecule axis on PLY2. Two unpaired electrons between two layers are gradually shifted to the upper layer with increasing of the external electric field strength (Fext): the weaker the two-electron/12-center bonding, the stronger the electrostatic interaction between two layers. Significantly, a small increment of Fext makes a big difference: the interlayer distance in the PLY2 is sharply elongated from 3.241 A (Fext = 203 × 10–4 au) to 3.485 A (Fext = 204 × 10–4 au), which leads to the two-electron/12-center bonding breaking at 204 × 10–4 au. Therefore, the Fext = 204 × 10–4 au is regarde...

The intermolecular stacking and crystallization of perylene diimides (PDIs) has become research obstacles for small molecule acceptors (SMAs). For breaking molecular rigidity and planarity, it is an executable way to increase the distortion between two PDI units. A class of PDI dimers were designed via bridging different linkers in bay positions (1–1′ bridge) and headland positions (1–2′ bridge) to screen suitable acceptor materials for organic photovoltaic cells (OPVs). Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were performed to investigate their electronic structures, open circuit voltage (VOC), driving forces (ΔEL-L), and some major parameters related to the short-circuit current density (JSC) such as absorption spectrum and carrier transport ability. Meanwhile, the intermolecular charge transfer (inter-CT) and charge recombination (inter-CR) rates were calculated for a further analysis on charge transfer properties at donor/acceptor (D/A) interf...

We designed and fabricated a fluorophore-containing tetradentate carboxylate ligand-based metal–organic framework (MOF) material with open and semiopen channels, which acted as the host for sulfur trapped in Li–S batteries and sensor of benzene homologues. These channels efficiently provide a π–π* conjugated matrix for the charge transfer and guest molecule trapping. The open channel ensured a much higher loading quantitative of sulfur (S content-active material, 72 wt %; electrode, 50.4 wt %) than most of the MOF/sulfur composites, while the semiopen channel possessing aromatic rings tentacles guaranteed an outstanding specific discharge capacity (1092 mA h g–1 at 0.1 C) accompanied by good cycling stability. To our surprise, benefiting from special π–π* conjugated conditions, compound 1 could be a chemical sensor for benzene homologues, especially for 1,2,4-trimethylbenzene (1,2,4-TMB). This is the first example of MOFs materials serving as a sensor of 1,2,4-TMB among benzene homologues. Our works may b...

Five neutral heteroleptic Ir(III) complexes 1–5 using the same cyclometalated ligand and different pyridine-1,2,4-triazolyl derivatives as ancillary ligands with fluorine substituents attached, were rationally designed and prepared. Their photophysical, electrochemical, and thermal properties were studied, and theoretical calculations were performed to understand the emission behaviors as well. Introducing fluorine atoms has little effect on the photophysical and thermal properties, but the performances of the resulting devices can be fine-tuned. Among them, a heavy doping level device employing a phosphor with five fluorine atoms delivers superior device efficiencies with ηc = 32.6 cd A–1 and ηp = 27.6 lm W–1, respectively, which is higher than those of other counterparts. Importantly, such a device exhibits almost negligible roll-off in luminance efficiency. Despite nondoped devices achieving good EL performance, more fluorine atoms lead to a relatively higher efficiency roll-off. The results suggest th...

The cleavage of inert C-C bonds is a central challenge in modern chemistry. Multinuclear transition metal complexes would be a desirable alternative because of the synergetic effect of multiple metal centers. In this work, carbon-carbon bond cleavage and rearrangement of benzene by a trinuclear titanium hydride were investigated using density functional theory. The reaction occurs via a novel "two-state reactivity" mechanism. The important elementary steps consist of hydride transfer, benzene coordination, dehydrogenation, oxidative addition, hydride-proton exchange, and reductive elimination. Most importantly, the ground-state potential energy surface switches from nearly degenerate triplet and antiferromagnetic singlet states to a closed-shell singlet state in the dearomatization of benzene, which effectively decreases the activation barrier. Furthermore, the roles of the transition metal centers and hydrides were clarified.