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We develop the effective modification strategy based on molecular engineering of s-triazine and its derivatives to improve the photoelectric performance of all-inorganic perovskites (AIP) for the first time. The surface modification strategy with cyanuric acid successfully increases the PLQY of AIP from 40.55% to 88.15%, and significantly enhances the current of the AIP film under 3 V by almost 20-fold (from 4.44 mA to 81.20 mA). This work has proven the effectiveness of improving the photoelectric performances of AIP via s-triazine and its derivatives and also suggested the potential risks of reducing the photoelectric performance of AIP due to inappropriate substituents in conjugated organic ligands.

Chirality is a fundamental feature of a structure, and chiral systems have been widely applied in many fields. This work mainly paid attention to effects of chiral interaction on molecular nonlinear optical (NLO) response. To this aim, D- or L-type alanine (Ala) with right or left handness respectively were added into chiral single-wall carbon nanotube (CNT) in this work. As a result by theoretical calculation, homo-chiral complex, namely, right-handed CNT with (D)-type Ala (or left-handed CNT with (L)-type Ala) would bring little stronger Ala-CNT interaction and larger first-order static hyperpolarizability βtot. In addition, βtot difference arising from charge transfer transition could be tuned by changing length and (or) chirality of CNT. These consequences were meaningful for further exploration of controlling molecular NLO properties by chirality.

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.

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.

Fabricating proton exchange membranes (PEMs) with high ionic conductivity and ideal mechanical robustness through regulation of the membrane microstructures achieved by molecular-level hybridization remains essential but challenging for the further development of high-performance PEM fuel cells. In this work, by precisely hybridizing nano-scaled bismuth oxide clusters into Nafion, we have fabricated the high-performance hybrid membrane, Nafion-Bi12 -3 %, which showed a proton conductivity of 386 mS cm-1 at 80 °C in aqueous solution with low methanol permeability, and conserved the ideal mechanical and chemical stabilities as PEMs. Moreover, molecular dynamics (MD) simulation was employed to clarify the structural properties and the assembly mechanisms of the hybrid membrane on the molecular level. The maximum current density and power density of Nafion-Bi12 -3 % for direct methanol fuel cells reached to 432.7 mA cm-2 and 110.2 mW cm-2 , respectively. This work provides new insights into the design of versatile functional polymer electrolyte membranes through polyoxometalate hybridization.

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.

It is a promising strategy to prepare composite photocatalysts based on MOFs and semiconductors for enhancing photocatalytic reduction of carbon dioxide (CO2). A family of binary composite photocatalysts (CdS@UiO-66-NH2) with different CdS contents have been designed and synthesized, which have been explored for photocatalytic reduction of CO2. CdS@UiO-66-NH2 can efficiently convert CO2 into CO under visible light irradiation via the solid–gas mode in the absence of sacrificial agents and photosensitizers. The generation rate of CO can reach up to 280.5 μmol g−1 h−1, which is 2.13-fold and 2.9-fold improvements over the pristine CdS and UiO-66-NH2, respectively, and the selectivity for CO is very high. Furthermore, this kind of photocatalysts can still maintain great photocatalytic activity in CO2/N2 mixed atmosphere with different CO2 concentrations. The outstanding performances of CdS@UiO-66-NH2 may be attributed to the existence of the direct Z-scheme heterojunction, which possesses the enhanced separation and migration of photo-generated charge carriers between UiO-66-NH2 and CdS, available specific surface areas and improved visible light absorption ability as well as abundant reaction active sites. This case reveals that MOF-based composite photocatalysts exhibit promising potential applications in the field of CO2 conversion.

Nonconventional chromophores, without classic conjugation and rigid units, are a hot topic of luminescent materials nowadays because of their unique under-explored fundamental properties and their promising applications. Despite the increased attention recently paid to this exciting area, the structural design and the mechanism of photoluminescence in these materials remain unclear and controversial. Different luminescence mechanisms have been successively proposed in recent years, such as oxidation, aggregation of carbonyl units, interactions with phenyl groups, clustering of chromophores and through-space conjugation, etc. This review summarizes oligomers/polymers with unconventional chromophores reported in recent years, which are classified according to their chemical structures and luminescence mechanisms. We present an interconnected overview of the topic highlighting the opportunities for new materials synthesis, looking forward to accelerated future innovation and developments in this area.

A novel 3D MOF [(Zn4O)(H2O)2(TPA)2]·8DMA (1) (H3TPA = 4,4′,4′′-nitrilotrisbenzoic acid; DMA = N,N-dimethylacetamide) with tetragonal nanochannels has been rationally obtained under solvothermal conditions using the fluorescent ligand H3TPA. MOF 1 demonstrates a unique (3,6)-connected network with nanosized square channels, displaying strong blue emission. Interestingly, 1 can be used as a fluorescent probe, which can detect nitroaromatic explosives efficiently and selectively via fluorescence quenching phenomena. As the number of –NO2 groups increase, fluorescence quenching becomes more obvious, which is maybe because the energy transfer from the electron-donating framework to electron-withdrawing nitroaromatic analytes becomes greater. Notably, the sensor is particularly sensitive to picric acid (PA), showing complete fluorescence quenching at a PA concentration as low as 30 ppm. MOF 1 can be recycled in the detection of nitroaromatic explosives with excellent recyclability. Additionally, the photo-induced electron transfer mechanism was validated through theoretical calculations for the fluorescence quenching.

Two tetra-nuclear YbIII-incorporated selenotungstate clusters, Keggin (C2H8N)6Na14[Yb4Se6W44O160(H2O)12]·40H2O (1) and Wells–Dawson (C2H8N)4Na14[Yb4Se6W45O159(OH)6(H2O)11]·38H2O (2), have been isolated through a pH-controlled assembly, which exhibit the first YbIII-containing polyoxotungstates with selenium heteroatoms. Their assemblies rely on the structure-directing effects of SeO32− anion templates to give rise to available Se-containing Keggin-/Wells–Dawson-type motifs. Both compounds were characterized by single-crystal X-ray diffraction, IR spectroscopy, power X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) as well as electrospray ionization mass spectrometry (ESI-MS). Furthermore, systematic magnetic studies revealed that 1 exhibits field-induced single-molecule magnetic behavior with a pre-exponential factor of τ0 = 6.60(7) × 10−8 s and a relaxation energy barrier of ΔE/kB = 39.44(2) K, while 2 only displays antiferromagnetic interactions between the ytterbium centers.

The tridentate ligand 2,4,6-tris(2-(pyridin-4-yl)vinyl)-1,3,5-triazine (TPVT) was designed and synthesized. We prepared metal–organic framework (TPVT-MOFs) crystals containing TPVT, 1,3,5-benzenetricarboxylic acid and cobalt by solvothermal reaction. Then, a series of composite materials with different contents of TPVT-MOFs were obtained by combining TPVT-MOFs with g-C3N4. Due to the interaction between TPVT-MOFs and g-C3N4, the composite materials have a more favorable valence band (VB) and conduction band (CB) for photocatalytic reduction of CO2 and oxidation of H2O. Under the conditions of visible light and a gas–solid system without a co-catalyst, a photosensitizer and a sacrificial agent, the yield of CO2 reduction by TPVT-MOFs@g-C3N4-10 can reach 56.4 μmol·g−1·h−1, which is 3.2 times that of pure g-C3N4 (17.5 μmol·g−1·h−1). The results of DFT calculations showed that the adsorption of H2O on the TPVT-MOFs@g-C3N4 composite material was more preferential, which promoted the adsorption and reduction of CO2.

An inner electric field generated between the electrode and the counter electrode when DSSCs work has an inevitable effect on the conversion efficiency, and it is important to reveal the influence of the electric field direction and strength on the performance of DSSCs. Theoretical calculations based on density functional theory (DFT) and time-dependent DFT (TD-DFT) were employed to analyze the electronic structures, optical properties and electron transfer processes under on-field and off-field conditions. The interfacial electron transfer (IET) processes across the semiconductor interface were evaluated, which have been less investigated previously. Compared to the off-field condition, the conversion efficiency of DSSCs is increased when the electric field acted on the +X axis due to the broader absorption spectra, larger ICT parameters, and larger short-circuit photocurrent density governed by the injection driving force. In addition, the further increased conversion efficiency with increased electric field strength indicates that the POM-based dye has self-promoting properties, meaning that the generated inner electric field increases the light harvesting properties of the POM-based-dye, which in turn forms stronger electric field strengths, and finally improves the performance of DSSCs. It is expected that the present study could establish the relationship between the electric field and DSSC efficiency.

The efficient activation of the adsorbed N2 is the initial and crucial step in the electrochemical nitrogen reduction reaction (NRR), but remains a long-standing challenge. Attaching long-distance heterometal M and M′ metals from the two ends of NN (like a curved bonding in Ag2C2) is an ingenious strategy to promote the activation and polarization of the intrinsic triple bond during electrocatalysis. Motivated by this strategy and the excellent stability and larger size of the B7-unit, the global-minimum MM′B7 monolayers with elongated heterometal double-sites as promising NRR electrocatalysts have been identified from the 10 179 candidates using high-throughput screening. The TiNbB7 monolayer with a metal distance of 3.56 A exhibits the optimal NRR catalytic activity with the limiting potential of 0.04 V and the kinetic energy barrier of 0.75 eV through the mixed mechanism, together with a strong capability of suppressing the competitive hydrogen evolution reaction and the surface oxidation. The other eight global-minimum systems (NbMoB7, ScHfB7, ScNbB7, ScTaB7, ScZrB7, TiHfB7, TiNbB7 and ZrHfB7) also possess excellent catalytic activity, and the highest limiting potential is only 0.62 V. These data adequately verify that long-distance heterometal double-sites are an excellent strategy to active and polarize the NN triple bond due to the elongated bonding length, asymmetric interaction and favorite orbital matching for the side-on adsorbed N2 molecule on double-sites. Most importantly, this work opens a new avenue to design and develop efficient NRR electrocatalysts with the long-distance heterometal double-sites.

Antibiotics as newly emerging organic pollutants are arousing more and more serious environmental issues. Meantime, metal–organic frameworks (MOFs) are considered as promising adsorbents to remove antibiotics. To overcome the limitations of large-scale applications for MOFs in the powder form, herein, we proposed a strategy of in-situ growth ZIF-67 onto polyaniline (PANI) modified regenerated cellulose aerogel (RCA). First, RCA was obtained by chemical cross-linking and physical cross-linking method. Then, PANI played the role of metal chelated layers, which were coated on RCA by in-situ polymerization. Finally, ZIF-67 nanocrystals were in-situ growth on the surface of the PANI coated regenerated cellulose aerogel to synthesise the composite adsorbent ZIF-67/PANI/RCA. The loading mass ratios of ZIF-67 on RCA and PANI/RCA were 25.39% and 42.38%, respectively, which indicates that PANI as interface layers can effectively promote the in-situ growth of ZIF-67 compared with pure RCA. The obtained composite adsorbent (ZIF-67/PANI/RCA) was applied for the adsorption of tetracycline (TC) with high adsorption capacity (409.55 mg·g−1) and good recycling ability. After six cycles of adsorption–desorption, the removal efficiency toward TC was still over 94%. This strategy may provide an effective and versatile pathway to increase MOF loading mass on aerogel and sequentially branch out their applications in pollutant treatment fields.

Systematic design and self-assembly of metal-organic polyhedra with predictable configuration has been a long-standing challenge in crystal engineering due to the difficulty of finding suitable building units. Herein, we are focused on a concave polyoxovanadate cluster [V6O6(OCH3)9(SO4)4]5- that can be generated in situ under the exact reaction conditions. Based on this cluster, a potential trivalent molecular building block [V6O6(OCH3)9(SO4)(CO2)3]2- can be obtained by the bridging-ligand-substitution strategy that possesses appropriate angle information for the design of molecular cubes. Utilizing the face-directed assembly of the trivalent molecular building block and a diverse set of tetratopic carboxylate linkers, a series of metal-organic cubes VMOC-1 to VMOC-5 with the same topology but different functionalities and dimensions are designed and constructed. The inclusion study made with VMOC-3 as an example has shown that they are potential molecular receptors and can selectively capture size-matching polycyclic aromatic hydrocarbon guest molecules.

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...

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.

Porous covalent organic frameworks (COFs), as an emerging material, have the characteristics of high stability, large series of components, easy synthesis, modification, and adjustable amplitude. They have the potential to become good catalysts. Bromine, as a halogen, has attracted intensive interest for the modification of photocatalysts for photocatalytic reactions. It is feasible to enhance the activity and selectivity of the material by facile functionalization of the reticular parent structure's electron-withdrawing groups. In addition, the conjugation effect of bromine, further delocalizing the electrons of the COF, is beneficial to the progress of many photocatalytic reactions. Reports on the modification of COFs by bromine functional groups to improve the catalytic performance have not been found so far. Here, TAPP [5,10,15,20-tetrakis(4-aminophenyl)porphyrin] and 2,5-dibromo-1,4-benzenedialdehyde instead of terephthalaldehyde were chosen to synthesize a porphyrin-based COF (TAPBB-COF) by the solvothermal method. As expected, the valence band (VB) of TAPBB-COF is thus adjusted to a more suitable position. Additionally, the CO production when using TAPBB-COF under full-wavelength light for 12 h was 295.2 μmol g-1 , which was three times that of COF-366, and the new material has good recycling stability and selectivity (95.6 %). Theoretical calculations indicate that the nitrogen of the porphyrin ring and the Schiff base, and the bromine in TAPBB-COF contribute greatly to the activation of H2 O and the conversion of CO2 in the photoreaction.

Zn=Zn double bonded-especially double-π bonded-systems are scarce due to strong Coulomb repulsion caused by the Zn atom's internally crowded d electrons and very high energy of the virtual π orbitals in Zn2 fragments. It is also rare for Zn atoms to exhibit negative oxidation states within reported Zn-Zn bonded complexes. Herein, we report Zn=Zn double-π bonded octahedral clusters Zn2 M4 (M=Li, Na) bridged by four alkali metal ligands, in which the central Zn atom is in a negative oxidation state. Especially in D4h -Zn2 Na4 , the natural population analysis shows that the charge of the Zn atom reaches up to -0.89 |e| (-1.11 |e| for AIM charge). Although this cooperation inevitably increases the repulsion between two Zn atoms, the introduction of the s1 -type ligands results in occupation of degenerated π orbitals and the electrons being delocalized over the whole octahedral framework as well, in turn stabilizing the octahedral molecular structure. This study demonstrates that maintaining the degeneracy of the π orbitals and introducing electrons from equatorial plane are effective means to construct double-π bonds between transitional metals.

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...

Blue-emitting gels are scarce, especially oligomeric/polymeric systems. Here, a series of 4,4′-sulfonyldiphenol (SDP) based oligourethane derivatives (OUs), namely OUHDI, OUHMDI and OUTDI based on 1,6-hexamethylene diisocyanate, 4,4′-methylenebis(cyclohexyl isocyanate) and 2,4-diisocyanatotoluene, respectively, were rationally designed and obtained by simple procedures. The new oligomers all display aggregation-induced blue fluorescence and upon gelation they achieve enhanced bright deep-blue emission as a result of interchain hydrogen bonding and oxygen cluster interactions. The OUs show spontaneous thermoreversible gelation in solvents which possess hydrogen-bond receptor units (C[double bond, length as m-dash]O or S[double bond, length as m-dash]O) which facilitate self-assembly of the OU chains into nanotubes. The oligourethane gels (OUGs) possess excellent ability for resisting external stress while at the same time exhibiting a distinct viscous flow state. The results illustrate that heteroatomic non-conjugated oligomers with advantageous hydrogen bonding interactions and oxygen clusters provide an efficient route to photoluminescent blue-emitting gels. The thermoreversible OUGs with excellent mechanical properties have been exploited to make sticky coatings, transparent films and a blue fluorescent molded shape using simple fabrication processes.

The development of metal complexes for optoelectronic applications is a fertile area of research. In contrast to the rigorous development of mononuclear metal complexes, dinuclear species have been less well studied and their fundamental chemistry and applications are under-explored. However, dinuclear species present special properties and functions compared with mononuclear species as a consequence of tuning the bridging ligands, the cyclometalated ligands or the two metal centers. More recently, dinuclear species have enabled important breakthroughs in the fields of OLEDs, photocatalytic water splitting and CO2 reduction, DSPEC, chemosensors, biosensors, PDT, smart materials and so on. Here we present an overview of recent developments of dinuclear metal complexes, their multifunctional properties and their various applications. The relationship between structure and property of dinuclear species and important factors which influence device performance are discussed. Finally, we illustrate some challenges and opportunities for future research into dinuclear metal complexes. This review aims to provide an up-to-date summary and outlook of functional dinuclear metal complexes and to stimulate more researchers to contribute to this exciting interdisciplinary field.

Theoretical calculations based on the density functional theory (DFT) and time-dependent DFT (TD-DFT) were employed to screen efficient acceptor group candidates for POM-based dyes. Compared to the commonly used cyanoacrylic acid acceptor group in dye 1, the acceptor groups, namely 2-hydroxy-4-(methyleneamino)benzoic acid, 5-methylenepyrimidine-2,4,6(1H,3H,5H)-trione and 5-methyleneimidazolidine-2,4-dione, in dyes 2–4 showed increased adsorption ability onto the TiO2 surface, which is beneficial for device stability. The reduced density gradient analysis offered a rich visualization of the weak interactions between the two monomers in the dimers of the dyes, indicating that the retarded aggregation in dyes 2–4 resulted from the hydrogen bonds present in the dimers of dyes 2–4, while π–π stacking interactions also existed in the dimer of dye 1. Particularly, dye 3 not only exhibited the broadest absorption spectrum, largest ICT parameters, largest short-circuit photocurrent density governed by electronic coupling and largest open-circuit photovoltage connected with the energy shift of the conduction band among dyes 1–4, but also possessed superior adsorption stability and the lowest interaction energy for the most stable dimer configuration, which can improve the photovoltaic efficiency of DSSCs. Thus, the 5-methylenepyrimidine-2,4,6(1H,3H,5H)-trione acceptor group in dye 3 can be a promising acceptor group candidate for high-performance dyes used in DSSCs.

The physical confinement and chemical catalysis of lithium polysulfides (LiPSs) are effective approaches to improve the performance of lithium–sulfur (Li–S) batteries. How to effectively combine physical confinement and chemical catalysis has become the focus of research. Herein, micro–mesoporous carbon (MMC) embedded with well-dispersed ultrafine CoS2 (uCoS2) nanocrystals as an efficient sulfur host is presented. As expected, the obtained S/uCoS2@MMC cathode can achieve a synergistic effect of physical confinement and chemical catalysis of LiPSs through micro–mesoporous structures and well-dispersed uCoS2 nanocrystals. Furthermore, the MMC with a high conductive specific surface area, uniform pore size and micro–mesoporous structure can realize homogeneous loading of sulfur and physical adsorption of LiPSs. Owing to these excellent qualities, the S/uCoS2@MMC cathode delivers outstanding initial capacities up to 1227 mA h g−1 at 0.1C. More significantly, a capacity of 606 mA h g−1 is maintained after 1000 cycles at 1C (a very low capacity decay rate of only 0.032% per cycle). It can be seen that the MMC embedded with well-dispersed uCoS2 nanocrystals as the sulfur host has great application prospects in Li–S batteries.

Light irradiation can affect electronic properties of catalysts and the introduction of appropriate light into electrocatalysts may have a significant impact on the electrocatalytic process; however, this has not been fully studied. Herein, we propose a photo-activated process cascaded electrocatalysis for CO2 reduction to produce syngas over a core–shell ZIF-8@Co/C catalyst. Under light irradiation, the onset potential and overpotential of ZIF-8@Co/C positively shift by 40 and 200 mV, and the syngas production is enhanced 5.2-fold at a bias potential of −0.9 V vs. RHE. It is noteworthy that the electric energy efficiency is enhanced by 30%. Deducting syngas generated by electricity, the solar-to-syngas conversion efficiency (joule to joule) is as high as 5.38%, which outperforms reported photoelectrochemical systems. These devices also relatively maintain high efficiency in neutral pH aqueous solution. Dedicated experiments and in situ transient photovoltage studies demonstrate that the cascaded photo-activation of CO2 and H+ in electrocatalysis accounts for the outstanding catalytic performance.

Host materials that can physically confine and chemically adsorb/catalyze lithium polysulfides (LiPSs) are currently receiving intensive research interest for developing lithium–sulfur (Li–S) batteries. Herein, a novel host material made of micro–mesoporous carbon nanospheres (MMC NSs) with well-dispersed ultrafine NiS2-ZnS (uNiS2-ZnS) heterostructures is synthesized for the first time via a simple in situ sulfuration process. The uNiS2-ZnS/MMC materials achieve the synergistic effect of physical confinement and the efficient chemical adsorption/catalysis of LiPSs through a micro–mesoporous structure and well-dispersed uNiS2-ZnS heterostructures. In addition, compared with bulk heterostructured materials, the uNiS2-ZnS heterostructures greatly enhance the adsorption and catalytic ability toward LiPSs because the catalysis interface effect and naturally formed in-plane interfaces can be magnified by the ultrafine dispersed nanoparticles. As a result, the prepared uNiS2-ZnS/MMC-S cathodes exhibit outstanding rate capacity (675.5 mA h g−1 at 5.0C) and cyclic stability (710.5 mA h g−1 at 1.0C after 1000 cycles with a low capacity decay of 0.033% per cycle). This work provides a certain reference for the application of heterostructured materials in Li–S batteries.

Developing multifunctional photosensitizers (PSs) is needed to effectively simplify cancer treatment, but it remains a big challenge. Here, two red-emitting AIE-active, donor–acceptor (D–A) PSs with small ΔEST and their AIE nanoparticles, are rationally designed and synthesized. The PS1 NPs exhibit bright red-emission with high quantum yield, appropriate 1O2 generation ability and good biocompatibility. More importantly, PS1 NPs can strongly light up the cytoplasm by gently shaking the cells for only 5 s at room temperature, indicating ultrafast staining and mild incubation conditions. In vitro and in vivo cell tracing demonstrate that PS1 NPs can track cells over 14 days, and effectively inhibit tumor growth upon irradiation. To the best of our knowledge, this work is the first example of a PS that integrates image-guided PDT, ultrafast staining and long-term tracing functions, demonstrating the “all-in-one” concept which offers great advantages for potential clinical applications., Developing multifunctional photosensitizers (PSs) is needed to effectively simplify cancer treatment, but it remains a big challenge.

Adequate studies have confirmed that polyoxometalates (POMs) are preeminent multi-electron donors and metalloporphyrins are electrochemically generated active catalysts for the CO2 reduction reaction. Integrating electron-rich POMs with metalloporphyrins in a metallic and stable organic framework can create facile and fascinating heterogeneous electrochemical catalysts by merging their complementary advantages and extensive promising possibilities. Herein, we designed and screened a series of stable and metallic two-dimensional (2D) polyoxometalate–metalloporphyrin organic frameworks (TM–PMOFs, TM in porphyrin = Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Os, Ir, or Pt) constructed by linking reductive Lindqvist-type hexamolybdate ([Mo6]2e/2H) with 4-connected tetra-(4-aminophenyl) metalloporphyrin (TM-TAPP) building structs through the MoN triple bond, whose CO2 electrochemical reduction performances and processes are studied in detail by means of density functional theory (DFT). Our computations reveal that the Lindqvist-type clusters [Mo6]2e/2H act as multi-electron regulators for the reduction reaction, and then the most promising catalyst for the reduction from CO2 to CH4 has the lowest theoretical driven potential (0.41 V). Moreover, the [Mo6]2e/2H units inside are easily reduced from the [Mo6] with a driven potential (0.08 V). Our work will encourage more experimental studies to further explore metallic 2D PMOF materials for CO2 electrochemical reduction.

Highly luminous lanthanide metal–organic gels (Ln-MOGs) can act as fluorescent probes for the detection of organic amines and can also be used to build white-light emitting materials based on the different luminescent properties of lanthanide ions. Here, we reported a Ln-MOG constructed with a 3,5-di(2′,4′-dicarboxylphenyl)benozoic acid (DPBA) ligand and Tb3+. Tb-MOG has an excellent fluorescence detection effect on organic amines including ethylenediamine, triethylamine, diisopropylamine and aniline in aqueous solution, and their detection limits reach a sub-ppm level. Considering the practicality, a Tb-MOG testing paper was prepared by a spin coating process, which can detect volatile organic amine vapors with good recyclability. Additionally, a single-phase white-light Tb0.84Eu0.16-MOG material was realized by in situ doping of Tb-MOG with Eu3+ and reasonably utilizing the blue emission of DPBA.

Two Ni/Co-substituted sandwich-type germanomolybdates, {[M3(NH2-trz)6(H2O)6][M4(H2O)2(HGeMo10O36)2]}·nH2O (M = Ni2+ (1) and Co2+ (2), n = 10 (1) or 11 (2), NH2-trz = 4-amino-1,2,4-triazole), have been obtained under hydrothermal conditions. 1 and 2 represent the first trivacant Keggin germanomolybdates involving unprecedented [α-GeMo10O36]8− fragments and {M3O4} quasi-cubane building units. Both of them exhibit electrocatalytic behaviours for H2O2 reduction and photocatalytic properties for CO2 conversion.

Two new aggregation-induced emission (AIE)-active cyclemetalated cationic Ir(iii) complexes have been rationally designed and synthesized by introducing O-H substituents into Schiff base ligands. π-Hydrogen bonding is successfully exploited for the first time to realize the mechanochromic luminescence (MCL) property by the synergistic effect of O-H and F substituents in complex 1. An X-ray crystal structure analysis of the two complexes suggests that the intramolecular hydrogen bonding effectively restricted the molecular motions, thus causing typical AIE characteristics. More importantly, a loosely packed structure constructed from intermolecular hydrogen bonding interactions (O-Hπ and C-HF) is obtained, and it is susceptible to mechanical stimulation. Powder X-ray diffraction (PXRD) studies also prove that the MCL behavior of complex 1 is caused by the reversible phase transition from crystalline to amorphous state under grinding and solvent recrystallization, leading to a change in emission colors. A re-writable phosphorescence data recording device was fabricated using complex 1 as the active material. Our molecular design strategies provide a new avenue for achieving efficient phosphorescence materials with AIE and MCL properties.

The electronic properties of dyes can be readily tuned by modifying the structure. Herein, the polyoxometalate (POM)-based dyes derived from dye XW11 with new patterns, donor-acceptor-π linker-acceptor (D-A-π-A) structure (dye 1), and D-π-A-π-A structure (dye 2) were designed by inserting a POM moiety besides the extensively exploited D-π-A structure (dye 3). Based on density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations, the configuration effect on the designed dyes was investigated. The results indicate that dye 3 possesses the largest short-circuit photocurrent density JSC due to the red-shifted absorption spectra, superior intramolecular charge transfer (ICT) parameters and the largest electron injection efficiency. At the same time, dye 1 with a D-A-π-A structure not only benefits the conduction band energy shift, but also retards the charge recombination and dye aggregation effect, which is beneficial for open-circuit photovoltage VOC. Moreover, the dynamics analysis of interfacial electron transfer shows that the electrons in dye 1 are almost completely injected after 14 fs, while it takes a long time for dyes 2 and 3. The present work is expected to establish a structure-property relationship for future dye design.

Electrocatalytic reduction of nitrogen (N2) is considered as a simple, green, and sustainable method for producing ammonia (NH3). Inspired by the recent experimental synthesis of a two-dimensional intrinsically conductive Ni-based covalent organic framework (Mirica et al., J. Am. Chem. Soc., 2019, 141, 11929–11937), here, on the basis of density functional theory (DFT), we explore the electrocatalytic performance of a series of stable and conductive two-dimensional (2D) TM-based covalent organic frameworks (TM-COFs, TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ru, Rh, Pd, Ag, W, Ir, Pt, and Au, respectively) toward the N2 reduction reaction (NRR), which are constructed by the robust linkage between 2,3,9,10,16,17,23,24-octaamino-metallophthalocyanine and pyrene-4,5,9,10-tetraone. The computational results show that the 2D conductive Mo-COF exhibits the highest electrocatalytic performance for N2 fixation with a very low overpotential of 0.16 V among the 20 candidates, and can effectively inhibit the competitive hydrogen evolution reaction (HER). The outstanding NRR activity and selectivity of the Mo-COF stem from its inherent superiorities, such as excellent electrical conductivity, significant positive charge and large spin moment on the Mo atom, and appropriate adsorption strength for NRR species. This work will promote more experimental research in this field to discover more highly active COF-based catalysts for advancing sustainable NH3 production.

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...

At present, most of the reported planar pentacoordinate clusters are similar to the isoelectronic substitution of CAl5+, with 18 counting electrons. Meanwhile, the regular planar pentacoordinate boron systems are rarely reported. Hereby, a sulphur-bridged BAl5S5+ system with a five-pointed star configuration and 17 counting electrons is identified at the global energy minimum through the particle-swarm optimization method, based on the previous recognition on bridged sulphur as the peripheral tactics to the stable planar tetracoordinate carbon and boron. Its outstanding stability has been demonstrated by thermodynamic analysis at 900 K, electronic properties and chemical bonding analysis. This study provides adequately theoretical basis and referable data for its experimental capture and testing.

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.

Three nanoscale Nb/W mixed-addendum polyoxometalates, Cs14K4[(Si4W36Nb12O156)Cu(H2O)2]·47H2O, Cs10K8[(Si4W36Nb12O156)Zn(H2O)2]·28H2O, and Cs16[(H2Si4W36Nb12O156)Cd(H2O)2]·75H2O involving [SiNb3W9O40]7− fundamental building unit, have been synthesized, which all show photocatalytic hydrogen evolution activities. Furthermore, molecules 1, 2, and 3 are stable in the photocatalytic hydrogen evolution system. The embedding transition-metal cations into Nb/W mixed-addendum POMs can improve the photocatalytic H2 evolution activity.

Nanostructured molybdenum disulfide (MoS2) is successfully embedded in the N-doped porous carbon to form micro-sized MoS2/N-C particles via a simple one-pot solution reaction. Yolk, a biomass carbon source with rich nitrogen and oxygen, makes a success to the heteroatom self-doping. The obtained N-doped porous carbon coating layers largely improve the conductivity and electrochemical activity. Moreover, the unique structure of MoS2 nanodots embedded in the porous carbon effectively combines the advantages of nanoscale MoS2 and micron scale N-doped C, which addresses the issues of MoS2 in lithium ion batteries (e.g., poor conductivity, sulfur loss and easy conglomeration). Interestingly, MoS2/N-C composite shows the first discharge/charge capacities of 1002 and 724 mAh g−1 at 0.1 A g−1 and stabilizes around 805 mAh g−1 after 100 cycles. Especially, it still remains at 630 mAh g−1 even under 0.5 A g−1 after 500 cycles, exhibiting excellent lithium ion (Li+) storage and cycle-to-cycle durability. This desired performance of MoS2/N-C is mainly resulted from the unique embedded structure, which effectively improves ion/electron transportation, ensures high sulfur reservation and prevents the conglomeration or accumulation during lithiation/delithiation reaction.

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...

In this study, we present the synthesis of Tb3Ga5O12 nanoparticles doped with Er3+, Yb3+, and Sc3+ ions, prepared using a co-precipitation method. These materials have well-defined magnetic-fluorescence properties. The effects of Yb3+ ion concentration on the structural characteristics, morphology, luminescence, and magnetic properties of the nanoparticles were investigated in detail using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, photoluminescence spectroscopy, and vibrating sample magnetometer measurements. Under 980-nm laser diode excitation, the nanoparticles displayed bright up-conversion luminescence, showing evidence of resonant energy transfer from the Yb3+ to Er3+ ions. Intense green and red emissions located at approximately 526, 548, and 656 nm were attributed to the radiant transitions of 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 of Er3+, respectively. These observations indicate that Tb3Ga5O12:Er3+, Yb3+, Sc3+ magnetic–fluorescent bifunctional nanoparticles are promising materials for use in bioimaging and magnetic bio-separation applications.

The PDCBT shows much better performance than P3HT in non-fullerene organic solar cell although the former only replaces hexyl by alkoxycarbonyl group compared with the latter. In this work, we will focus on this tiny difference in structure and huge difference in performance between these two polymers from theoretical perspective. Thus we present a comparative study based on the dependent/time-dependent density functional theory (DFT/TDDFT) calculations and molecular dynamic (MD) simulations. The results reveal that PDCBT not only possesses lower molecular orbital energy levels which leads to the increasement of the open circuit voltage (VOC), but also exhibits better planarity and larger hole mobility than P3HT. In particular, comparing with P3HT system, PDCBT system also displays the higher charge separation rate and smaller charge recombination rate both in hole transfer and electron transfer process at the interface, which promote the enhancement of short-circuit current density. Therefore, this work provides a fundamental understanding of the prominent influence of the replacement of hexyl group by alkoxycarbonyl in P3HT on the cell performance and also provides some theoretical guidance for further optimization of donor materials in non-fullerene organic solar cells (OSCs).

The nature of the 2e/12c bond and its conversion to a carbon-carbon single bond in phenalenyl dimers have prompted a great deal of interests recently. In this work, we theoretically investigated a series of π-stacking phenalenyl derivatives with 2e/12c bonding character by density functional theory (DFT) calculations to elucidate origin of this unusual bond conversion. Results show that bond-conversion of the phenalenyl dimer easily occurs at room-temperature both dynamically and thermodynamically. However, bond-conversion of hetero π-stacking adducts, in which the two center carbon atoms were substituted by boron and nitrogen atoms, respectively, is much more difficult, because the 2e/12c bond is stabilized by its charge transfer character. Consequently, the bond-conversion is an endothermic process, albeit with a low conversion barrier. Interestingly, Lewis acid-base interactions would be induced by substitution of the center nitrogen atom to phosphorus atom. The 2e/12c bond is further stabilized by 5.9 kcal mol-1 and its conversion is also thermodynamically unfavorable.

Inkjet printing technology is one of the most attractive methods for the realization of full-color patterning for displays. In this work, we successfully introduce this technology into fabricating pixelated light-emitting electrochemical cells (LECs). By carefully controlling the poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate), and cationic Ir(III) complexes ink formulation, as well as their inkjet printing properties, patterned LEC pixels in ultrahigh definition TV format was fabricated, leading to a resolution of 73 pixels per inch. The as-resulted inkjet-printed LEC exhibits a maximum luminance and a current efficiency of 3402 cd/m2, and 7.5 cd/A, respectively, which is close to that of the spin-coated one. This work paves a new way for the fabrication of low-cost material-efficient, pixelated light-emitting electrochemical cells.

In this work, iridium complexes 1–8 bearing bipyridine or pyridine-pyrimidine main ligand and picolinate ancillary ligand have been designed by varying the position of –OCH3 and phenyl groups at the ligands aiming at finding a better choice to design blue phosphors. The results indicate that an appropriate combination of –OCH3 and pyridine-pyrimidine ligand makes the emission wavelength a noticeable blue-shift. Moreover, the further introduction of phenyl group shifts the emission wavelength to a shorter region. In terms of the radiative decay rate constant (kr), the position of –OCH3 has a slight influence on it, but the introduction of phenyl group is conductive to enhancing this value. In particular, the 7 has the largest kr among the designed complexes up to 7.68 × 105 s−1. As for the non-radiative process, 1–6 have high barriers between 3MLCT and 3MC, indicating the difficulty of electron relaxation to the non-emissive 3MC structure. There is no transition state of 3MLCT↔3MC is found for 7 and 8 bearing pyridine-pyrimidine ligand. However, the barriers of all complexes for the S0/3MC minimum energy crossing point reaction are high, which is in favor of avoiding the system relaxes to the S0 geometry by non-radiative path.

Developing pure organic materials with ultralong lifetimes is attractive but challenging. Here we report a concise chemical approach to regulate the electronic configuration for phosphorescence enhancement. After the introduction of d-pπ bonds into a phenothiazine model system, a phosphorescence lifetime enhancement of up to 19 times was observed for DOPPMO, compared to the reference PPMO. A record phosphorescence lifetime of up to 876 ms was obtained in phosphorescent phenothiazine. Theoretical calculations and single-crystal analysis reveal that the d-pπ bond not only reduces the (n, π*) proportion of the T1 state, but also endows the rigid molecular environment with multiple intermolecular interactions, thus enabling long-lived phosphorescence. This finding makes a valuable contribution to the prolongation of phosphorescence lifetimes and the extension of the scope of phosphorescent materials.

The increased needs for sustainable energy storage devices make it urgent to develop novel supercapacitor electrode materials. An ingenious zipper-like NiCo2O4/Ni(OH)2 composite has been successfully grown on nickel foam via a one-pot hydrothermal method free of any template or catalyst. Owing to its close contact with the substrate, its distinguished zipper-like structure and unique ingredients, the specific capacitance of NiCo2O4/Ni(OH)2 was as high as 2721 mF cm−2 at 1 mA cm−2; 2161 mF cm−2 was obtained even at 50 mA cm−2; and it retained 86% capacity after 10000 cycles. The facile synthesis method and remarkable capacitive performance of the zipper-like NiCo2O4/Ni(OH)2 make it attractive for supercapacitor applications.

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...