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A solvent plays an important role in chemical synthesis. Herein, we report ionic liquid (IL)-promoted formylation of N(sp2)-heteroarenes with CO2 and H2 to produce formamides over the Pd/C nanocata...

A light-controlled artificial synapse, which mimics the human brain has been considered to be one of the ideal candidates for the fundamental physical architecture of a neuromorphic computing system owing to the possible abilities of high bandwidth and low power calculation. However, the low photosensitivity of synapse devices can affect the accuracy of recognition and classification in neuromorphic computing tasks. In this work, a planar light-controlled artificial synapse having high photosensitivity (Ion/Ioff > 1000) with a high photocurrent and a low dark current is realized based on a ZnO thin film grown by radiofrequency sputtering. The synaptic functions of the human brain such as sensory memory, short-term memory, long-term memory, duration-time-dependent-plasticity, light-intensity-dependent-plasticity, learning-experience behavior, neural facilitation, and spike-timing-dependent plasticity are successfully emulated using persistent photoconductivity characteristic of a ZnO thin film. Furthermore, the high classification accuracy of 90%, 92%, and 86% after 40 epochs for file type datasets, small digits, and large digit is realized with a three-layer neural network based on backpropagation where the numerical weights in the network layer are mapped directly to the conductance states of the experimental synapse devices. Finally, characterization and analysis reveal that oxygen vacancy defects and chemisorbed oxygen on the surface of the ZnO film are the main factors that determine the performance of the device.

Solar energy-driven photoreduction of CO2 to energy-rich chemicals is of significance for sustainable development but challenging. Herein, quinacridone (QA)/nBiVO4 (n=0.2-20, in which n stands for the mass ratio of BiVO4 to QA) nanocomposites were developed for photoreduction of CO2 . Characterization of the materials with Fourier-transform (FT)IR spectroscopy and X-ray photoelectron spectroscopy (XPS) pointed to QA/nBiVO4 preparation via hydrogen-bonding-directed self-assembly of QA on BiVO4 nanosheets. Using triethanolamine (TEOA) as a sacrifice reagent, QA/10BiVO4 showed the best performance, affording CO with a production rate of 407 μmol g-1 h-1 , 24 times higher than those of pure QA. It was indicated that the Z-scheme charge-transfer mechanism of QA/nBiVO4 could significantly improve the separation and transmission efficiency of photo-generated electrons and holes. This novel approach provides new insight for fabricating the composite photocatalytic materials of small molecule organic semiconductors and inorganic semiconductors with high efficiency for photocatalytic of reduction CO2 .

A novel four-site ionic liquid (IL) was designed via the neutralization of citrazinic acid with tetrabutylphosphonium hydroxide, which had the highest CO2 absorption capacity of 3.26 mol per molar ...

Li has been considered as the ultimate anode material for high energy density secondary Li batteries. However, its practical application has been limited due to its low Coulombic efficiency (CE) and the formation of lithium dendrites. Recently, we have developed a microspherical Li-carbon nanotube (Li-CNT) composite material passivated with octadecylphosphonic acid (OPA) self-assembled monolayer (SAM) exhibiting suppressed lithium dendrite formation and improved environmental/electrochemical stability. In this work, we demonstrated the significantly enhanced passivation effects of a SAM using dihexadecanoalkyl phosphate (DHP), a molecule that is comprised of double hydrophobic alkyl chains and forms a denser SAM on surfaces with large curvature. As a result, the DHP SAM delivers superior environmental and electrochemical stability to the OPA passivated Li-CNT material. In specific, the DHP passivated Li-CNT composite (DHP-Li-CNT) delivers a high CE of 99.25% under a 33.3% depth of discharge (DOD) at 1 C, when it is paired with a LiFePO4 cathode. The evolution of the SAM during cycling and the effects of DOD and current density on the CE of the DHP-Li-CNT anode have also been investigated. The improved SAM passivation constitutes an important step in achieving the goal of practically applicable Li anodes.

Direct hydrogenation of CO2 to C2+ hydrocarbons is very interesting, but achieving this transformation below 200 °C is challenging and seldom reported. Herein, a homogeneous catalytic system was developed composed of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6 ]), Pd(PtBu3 )2 , FeCl2 , and the ligand 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) for hydrogenation of CO2 under mild conditions, which resulted in C2 -C4 hydrocarbons in selectivities up to 98.3 C-mol % at 180 °C. The combination of [BMIm][PF6 ]) with Xantphos endowed the Pd-Fe catalysts with the ability of activating CO2 and H2 simultaneously via [HPd(PtBu3 )(BMIm-COO)(BMIm)(PF6 )Fe]+ species, thus catalyzing the formation of C2 -C4 hydrocarbons through CO2 hydrogenation. In addition, this catalytic system is stable and recyclable, which may have promising applications.

Solar-driven reduction of CO2 into renewable carbon forms is considered as an alternative approach to address global warming and the energy crisis but suffers from low efficiency of the photocatalysts. Herein, a direct Z-Scheme SnS2 /sulfur-bridged covalent triazine frameworks (S-CTFs) photocatalyst (denoted as SnS2 /S-CTFs) was developed, which could efficiently adsorb CO2 owing to the CO2 -philic feature of S-CTFs and promote separation of photoinduced electron-hole pairs. Under visible-light irradiation, SnS2 /S-CTFs exhibited excellent performance for CO2 photoreduction, yielding CO and CH4 with evolution rates of 123.6 and 43.4 μmol g-1 h-1 , respectively, much better than the most catalysts reported to date. This inorganic/organic hybrid with direct Z-Scheme structure for visible-light-driven CO2 photoreduction provides new insights for designing photocatalysts with high efficiency for solar-to-fuel conversion.

Synthesis of renewable acetic acid from CO2 and lignin was effectively achieved over an ionic liquid (e.g., [BMIm][Cl])-based catalytic system containing Ru–Rh bimetal catalyst (Ru3(CO)12 and RhI3) and LiI. As far as we know, this is the first initiative to produce acetic acid from lignin and CO2.

Developing efficient methods for the real-time detection of Zn2+ levels in biological systems is highly relevant to improving our understanding of the role of Zn2+ in the progression of Parkinson's disease (PD). In this work, a novel Schiff base based Zn2+ fluorescent probe (ZP) was designed, synthesized and systematically investigated. A significant turn-on effect on ZP upon the addition of Zn2+ was observed, accompanied by a blue-shift of the fluorescence spectra. ZP is sensitive to Zn2+ and has excellent selectivity against various biologically relevant cations, anions and amino acids. The sensing mechanism of ZP was studied by 1H NMR, MS, single crystal X-ray diffraction and theoretical calculations. The results showed that the response of ZP to Zn2+ was based on the chelation–hydrolysis-enhancement process. Upon bonding, Zn2+ hydrolyzes the Schiff base to an aldehyde precursor, the resulting aldehyde further coordinates to Zn2+ to form a more stable heterobimetallic complex leading to the emission enhancement and blue-shift. ZP was applied to imaging exogenous/endogenous Zn2+ in live HeLa cells. Furthermore, we successfully measured the Zn2+ levels using in vitro PD models, which provided a visualization method to better understand the relationship between Zn2+ levels and PD development.

A Rose bengal-functionalized porous organic polymer (RB-POP) was prepared with a specific surface area of up to 562 m2 g−1. In the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, RB-POP supported Ag(0) nanoparticles exhibited excellent performance for catalyzing cyclization of propargyl alcohols with CO2 at 30 °C, achieving a TOF of 5000 h−1, the highest value among the reported ones.

The reduction of CO2 with amines and H2 generally produces N-formylated or N-methylated compounds over different catalysts. Herein, we report the selective synthesis of formamides, 1,2-bis(N-heterocyclic)ethanes, and methylamines, which is achieved over an ionic liquid (IL, e.g., 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIm][BF4])–Pd/C catalytic system. By simply varying the reaction temperature, formamides and methylamines can be selectively produced, respectively, in high yields. Interestingly, 1,2-bis(N-heterocyclic)ethanes can also be obtained via the McMurry reaction of the formed formamide coupled with subsequent hydrogenation. It was found that [BMIm][BF4] can react with formamide to form a [BMIm]+–formamide adduct; thus combined with Pd/C it can catalyze McMurry coupling of formamide in the presence of H2 to afford 1,2-bis(N-heterocyclic)ethane. Moreover, Pd/C–[BMIm][BF4] can further catalyze the hydrogenolysis of 1,2-bis(N-heterocyclic)ethane to access methylamine. [BMIm][BF4]–Pd/C was tolerant to a wide substrate scope, giving the corresponding formamides, 1,2-bis(N-heterocyclic)ethanes or methylamines in moderate to high yields. This work develops a new route to produce N-methylamine and opens the way to produce 1,2-bis(N-heterocyclic)ethane from cyclic amine as well.

The solar energy-driven photoreduction of CO2 with H2O to hydrocarbon fuels is an interesting but challenging topic. Herein, we report porous nitrogen-deficient carbon nitride nanotubes with tunable nitrogen vacancies (NCN-T) for visible-light-driven photoreduction of CO2 to CO in the absence of any cocatalyst and sacrificial reagent. The NCN-T series were prepared via the thermal etching approach, which showed a specific surface area of up to 207 m2 g−1 and a CO2 uptake capacity of 4.06 wt%. It was indicated that the nitrogen vacancies in NCN-T not only promoted the utilization of visible-light by extending the spectral response range, but also served as centres for capturing photoexcited electrons, hence, efficiently inhibiting the recombination of radiative electron–hole pairs. As a consequence, the NCN-T catalysts achieved the highest CO formation rate of 43.9 μmol g−1 h−1, which was >9 times higher than that obtained over the bulk counterpart.

O-heterocycles have wide applications, and their efficient and green synthesis is very interesting. Herein, we report hydrogen-bonding catalyzed ring-closing metathesis of aliphatic ethers to O-heterocycles over ionic liquid (IL) catalyst under metal- and solvent-free conditions. The IL 1-butylsulfonate-3-methylimidazolium trifluoromethanesulfonate ([SO3 H-BMIm][OTf]) is discovered to show outstanding performance, better than the reported catalysts. An interface effect plays an important role in mediating the reaction rate due to the immiscibility between the products and the IL catalyst, and the products can be spontaneously separated. NMR analysis and DFT calculation suggest that a pair of cation and anion of [SO3 H-BMIm][OTf] could form three strong H-bonds with an ether molecule, which catalyze the ether transformation via a cyclic oxonium intermediate. A series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines and dioxane can be obtained from their corresponding ethers in excellent yields (e.g., >99 %). This work opens an efficient and metal-free way to produce O-heterocycles from aliphatic ethers.

Choline-based ionic liquids (Ch-ILs) with anions possessing interacting sites to attract CO2 were designed, which could capture CO2 with capacity >1.0 mol CO2 per molar IL under ambient conditions. Moreover, this kind of ILs combining with CuCl could catalyze the formylation of amines with CO2/H2 at 120 °C. Especially, choline imidazolate showed the best performance, affording a series of N-formamides in excellent yields. It was demonstrated that the IL activated CO2 and the synergistic effect between the IL and CuCl resulted in the high activity for catalysing the formylation of amines with CO2/H2.

Herein, a novel route to synthesize unsymmetrically N,N-disubstituted formamides is reported, which is achieved via reductive coupling of primary amine and aldehyde with CO2/H2 over a cobalt-based catalytic system composed of CoF2, P(CH2CH2PPh2)3 and K2CO3. The mechanism investigation indicates that a secondary amine is formed via hydrogenation of the imine originated from aldehyde and primary amine, which further reacts with HCOOH generated from CO2 hydrogenation, resulting in the formation of NNFA finally.

Nitroreductase (NTR) is a member of flavin-containing enzymes that exists widely in bacteria. Hypoxia, which is a characteristic of locally advanced solid tumors, resulting from an imbalance between oxygen consumption and supply, can result in NTR overexpression. Using either nicotinamide adenine dinucleotide (NADH) or nicotinamide adenine dinucleotide phosphate (NADPH) as a source of reducing equivalents, NTR can catalyze the reduction of nitroaromatic compounds to the corresponding amines. Based on this reduction mechanism, NTR can be applied not only in the bioremediation and degradation of organic nitrogen compounds, but also in the development of NTR-targeted fluorescent probes to detect the hypoxic status of cancer cells. This review aims to provide a summary of the progress in fluorescent probes for NTR in recent years and elucidate the main fluorescent mechanisms that have been applied to design probes.

The reductive formylation of aryl iodides/bromides to aryl aldehydes using CO2/H2 is presented for the first time. It was realized over a catalytic system composed of RhI3 or RhI3/Pd(dppp)Cl2 (dppp = 1,3-bis(diphenyphosphino)propane) and PPh3 in the presence of Ac2O/Et3N at 100 °C, affording aromatic aldehydes in good to excellent yields, together with good functional-group tolerance and broad substrate scope. The reaction proceeds through three cascade steps, involving HCOOH formation, CO release, and formylation of aryl halides.

Solar-energy-driven photoreduction of CO2 to hydrocarbon fuels is an interesting and challenging topic, which generally requires photocatalysts with the capability to capture and photoreduce CO2 simultaneously. Herein, we demonstrate that a N,O,P-containing covalent organic polymer (NOP-COP) prepared via condensation of hexachlorocyclotriphosphazene with barbituric acid can capture CO2 and further photocatalyze its reduction to CH4 under visible-light irradiation. The characterization information indicates that the incorporation of phosphorus in the skeleton of NOP-COP promoted the absorption of visible light and improved the lifetime of the photoinduced carriers. As a result, NOP-COP exhibited enhanced efficiency for photoreduction of CO2 compared with the N,O-containing polymer, affording CH4 as the sole carbonaceous product with a rate of 22.5 μmol gcat–1 h–1 and selectivity over 90%. This work provides insight into designing and fabricating polymeric photocatalysts for CO2 photoreduction to fuels.

CO2 incorporation into C–H bonds is an important and interesting topic. Herein a sequential protocol for C(sp)–H carboxylation by employing a metal-free C–H activation/catalytic silylation reaction in conjunction with KO t Bu-mediated carboxylation with CO2 was established, in which KO t Bu catalyzes silylation of terminal alkynes to form alkynylsilanes at low temperature, and simultaneously mediates carboxylation of the alkynesilanes with atmospheric CO2. Importantly, the carboxylation further promotes the silylation, which makes the whole reaction proceed very rapidly. Moreover, this methodology is simple and scalable, which is characterized by short reaction time, wide substrate scope, excellent functional-group tolerance and mild reaction conditions, affording a range of corresponding propiolic acid products in excellent yields in most cases. In addition, it also allows for a convenient 13C-labeling through the use of 13CO2.

Active control of nanocrystal optical and electrical properties is crucial for many of their applications. By electrochemical (de)lithiation of Cu2-xSe, a highly doped semiconductor, dynamic and reversible manipulation of its NIR plasmonics has been achieved. Spectroelectrochemistry results show that NIR plasmon red-shifted and reduced in intensity during lithiation, which can be reversed with perfect on-off switching over 100 cycles. Electrochemical impedance spectroscopy reveals that a Faradaic redox process during Cu2-xSe (de)lithiation is responsible for the optical modulation, rather than simple capacitive charging. XPS analysis identifies a reversible change in the redox state of selenide anion but not copper cation, consistent with DFT calculations. Our findings open up new possibilities for dynamical manipulation of vacancy-induced surface plasmon resonances and have important implications for their use in NIR optical switching and functional circuits.

Investigating the change in expression level of mercapto biomolecules (GSH/Cys/Hcy) necessitates a rapid detection method for a series of physiological and pathological processes. Herein, we present a ligand-displacement-based two-photon fluorogenic probe based on an Fe(iii) complex, TPFeS, which is a GSH/Cys/Hcy rapid detection fluorogenic probe for in vitro analysis and live cell/tissue/in vivo imaging. The "in situ" probe is non-fluorescent and was prepared from a 1 : 2 ratio of Fe(iii) and TPS, a novel two-photon (TP) fluorophore with excellent one-photon (OP) and TP properties under physiological conditions, as a fluorescent ligand. This probe shows a rapid and remarkable fluorescence restoration (OFF-ON) property due to the ligand-displacement reaction of mercapto biomolecules in a recyclable manner in vitro. A significant two-photon action cross-section, good selectivity for biothiols, low cytotoxicity, and insensitivity to pH over the biologically relevant pH range allowed the direct visualization of mercapto biomolecules at different levels between normal/drug-treated live cells, as well as in Drosophila brain tissues/zebrafish based on the use of two-photon fluorescence microscopy.

A mesoporous imine-functionalized organic polymer (Imine-POP) was prepared based on the reaction of an aryl ammonium salt with an aromatic aldehyde in water without any catalyst and template. The Pd coordinated Imine-POP exhibited high catalytic activity for the N-formylation of amines with CO2/H2 at 100 °C, affording a series of formamides in high yields.

The CO2-involved synthesis of chemicals is of great significance from a green and sustainable point of view. Herein, we present an efficient Co-based catalytic system composed of a commercially available Co salt, the tetradentate phosphine ligand P-(CH2CH2PPh2)3, and a base, denoted as [Co]/PP3/base, for the synthesis of formamides via the formylation of amines with CO2/H2. It was indicated that the selectivity of products (i.e., formamide or methylamine) could be tuned to some extent via changing the solvent and the base. Using ethanol as the solvent, the Co(ClO4)2·6H2O/PP3/K2CO3 system showed high activity for the production of formamides, affording product yields of 82–95%, together with its broad substrate scope. Exploration of the reaction mechanism indicated that formamide was formed with HCOOH as the intermediate, while the methylamine byproduct was produced with HCHO as the intermediate via the hydrogenolysis of dialkylaminomethane.

This paper, for the first time, presents a comprehensive study of the structure, thermal stability and photoluminescence properties of CaLaMgTaO6:Pr3+ phosphors for LED applications. Pr3+ ions exhibits two clusters of dominant emissions peaked at 495 nm (3P0→3H4) and 657 nm (3P0→3F2) from double perovskite-structure CaLaMgTaO6 compounds. Meanwhile, the samples cover the emission wavelength of commercial blue light-emitting diode (LED) chips with high internal quantum efficiency (IQE) of 30.25% upon 450 nm excitation. The mechanism of thermal quenching for this phosphor was investigated and the corresponding activation energy ΔE was determined to be 0.23 eV. The fabricated Pr3+ single doped CaLaMgTaO6 together with a 450 nm blue LED chip is well-matched with the absorption band of photosynthesis, phototropism, and photomorphogenesis. Furthermore, this phosphor along with commercially available phosphors was applied to fabrication of 450 nm UV chip and YAG:Ce3+ emitted a well-distributed warm white light with high color rendering index (CRI) of 84.1 and a correlated color temperature (CCT) of 3914 K. All of the results indicate that this novel phosphor can compensate for the red light and has potential applications in plant cultivation and warm white LEDs field.

Using sodium borohydride (NaBH4) as the reducing reagent, the reductive fomylation of amines with CO2 was realized at 100 °C under catalyst-free conditions, and a series of formylated products were obtained in excellent yields. The reaction mechanism investigation demonstrated that NaBH4 could react with CO2 to form intermediate, which further reacted with amines, producing the formylated compounds. It was indicated that three hydrogen atoms from NaBH4 could involve in the reductive formylation, and therefore only 0.5 equiv. NaBH4 relative to the substrate was enough for getting high product yields. In addition, NaBH4 was also very efficient for the reductive cyclization of o-phenylenediamine with CO2 to synthesize benzimidazoles. NaBH4 as an efficient reducing reagent for the CO2-involed reductive reactions may have promising applications.

The methylation of amines using methanol is a promising route to synthesize N-methylamines, and the development of cheap and efficient catalytic system for this reaction is of great significance. Herein, we reported a cobalt (Co)-based catalytic system, which was in situ formed from commercially available Co precursor and a tetradentate phosphine ligand P(CH2CH2PPh2)3 combined with K3PO4. This catalystic system was very effective for the selective production of dimethylated products from aliphatic amines and monomethylated ones from aromatic amines. The reaction mechanism was further investigated by control and isotope labelling experiments.

Inverted structure thin-film organic solar cells (OSCs) are becoming increasingly important as they deliver higher power conversion efficiency and demonstrate better long-term stability than conventional devices. However, the energy band alignment and the built-in field across the device, which are crucial in understanding the device operation, is yet to be directly characterized. Here we present a direct visualization of the energy level alignment in operando inverted structure poly(3-hexylthiophene) (P3HT): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) OSCs using cross-sectional scanning Kelvin probe microscopy. The raw data of measured energy level alignment appear to be inconsistent with each other, and sometimes can even be contradictory to the device polarity observed in current density-voltage measurements. It is identified to be caused by the tip/cantilever induced convolution effect, which may severely mask abrupt energy level offsets at the thin electrode interlayers. A numerical deconvolution method is devised to quantitatively recover the energy level alignment across the device, and reveals the non-uniform electric field distribution in photoactive layer.

A highly efficient Co-based catalytic system, composed of a commercially available Co salt, a tetradentate phosphine ligand P(CH2CH2PPh2)3(PP3), and a base (denoted as [Co]/PP3/base), is developed for the methylation of C(sp3)–H and C(sp2)-H bonds using methanol as a methylating reagent. The Co(BF4)2·6H2O/PP3/K2CO3 catalytic system showed high catalytic activity for the methylation of C–H bonds in aryl alkyl ketones, aryl acetonitriles, and indoles, with wide substrate scope and good functional group tolerance, and methyl-substituted products were obtained in good to excellent yields at 100 °C. This cheap, readily available, and highly efficient Co-based catalytic system may have promising applications in methylation reaction using methanol.

A series of tetrabutylphosphonium ([Bu4P]+)-based ionic liquids (ILs) with multiple-site for CO2 capture and activation in their anions are reported, which could efficiently catalyze the cyclization reaction of propargylic alcohols with CO2 at ambient conditions. Especially, the IL, [Bu4P]3[2,4-OPym-5-Ac], which has three interaction sites for attracting CO2 together with a pKa1 value of 9.13, exhibited the best performance, affording a series of α-alkylidene cyclic carbonates in moderate to good yields. The mechanism exploration demonstrated that IL served as a bifunctional catalyst with anion simultaneously activat-ing CO2 via multiple-site cooperative interactions and the C≡C triple bond in propargylic alcohol via inductive effect, thus resulting in the production of α-alkylidene cyclic carbonates..

Herein we present a simple, metal-free and versatile route to synthesize unsymmetrically N,N-disubstituted formamides (NNFAs) from CO2, primary amine and aldehyde promoted by ionic liquid (1-butyl-3-methylimidazolium chloride) at room temperature. This approach features wide scopes of amines and aldehydes, and various unsymmetrical NNFAs could be obtained in good to excellent yields. The ionic liquid can be reused at least five runs without obvious activity loss.

Pyridine-containing anion-based ionic liquids (PA-ILs) with two kinds of interaction sites to bind CO2, e.g., [P4444][2-OP], were found to be highly efficient for catalysing the cycloaddition reactions of atmospheric CO2 with epoxides at room temperature under metal- and halogen-free conditions, producing a series of cyclic carbonates in high yields. It was demonstrated that the cooperative interaction from two interaction sites in the anions of PA-ILs activated CO2, while the cation activated the epoxides substrates via coordination to the central P+ unit, thus resulting in the high activity of the IL catalysts.

Ni-rich layered oxides, such as LiNi0.8Co0.1Mn0.1O2 (NCM811), are considered as promising cathode materials for lithium-ion batteries due to their high energy density. However, Ni-rich layered oxides are prone to react with water and carbon dioxide in ambient air forming residual lithium compounds, resulting in deterioration of electrochemical performance and bringing a challenge to the cathode electrode preparation. In this work, we have, for the first time, demonstrated that the chemical stability of the NCM811 material in ambient air can be significantly enhanced by passivating the surface with a hydrophobic self-assembled monolayer (SAM) of octadecyl phosphate (OPA). As a result, the degradation reaction between the NCM811 material and ambient air and thus the electrochemical performance deterioration were significantly suppressed during ambient air exposure. Specifically, the 5C-rate capacity retention deterioration of the NCM811 sample during 14-day ambient air exposure has been decreased from 12 to 2% by OPA passivation. Furthermore, the 200-cycle capacity retention deterioration of the NCM811 sample after 7-day ambient air exposure has been improved from 23 to 0.7% by OPA passivation. These results are very important for the practical application of Ni-rich oxide since no need for controlling of humidity is required on the cathode manufacture; thus, the cost can be reduced. The concept of molecular self-assembly on the NCM811 material also open vast possibilities to design reagents for surface passivation of Ni-rich layered oxides.

As game-changers in the photovoltaic community, perovskite solar cells are making unprecedented progress while still facing grand challenges such as improving lifetime without impairing efficiency. Herein, two structurally alike polyaromatic molecules based on naphthalene-1,8-dicarboximide (NMI) and perylene-3,4-dicarboximide (PMI) with different molecular dipoles are applied to tackle this issue. Contrasting the electronically pull-pull cyanide-substituted PMI (9CN-PMI) with only Lewis-base groups, the push-pull 4-hydroxybiphenyl-substituted NMI (4OH-NMI) with both protonic and Lewis-base groups can provide better chemical passivation for both shallow- and deep-level defects. Moreover, combined theoretical and experimental studies show that the 4OH-NMI can bind more firmly with perovskite and the polyaromatic backbones create benign midgap states in the excited perovskite to suppress the damage by superoxide anions (energetic passivation). The polar and protonic nature of 4OH-NMI facilitates band alignment and regulates the viscosity of the precursor solution for thicker perovskite films with better morphology. Consequently, the 4OH-NMI-passivated perovskite films exhibit reduced grain boundaries and nearly three-times lower defect density, boosting the device efficiency to 23.7%. A more effective design of the passivator for perovskites with multi-passivation mechanisms is provided in this study.

Herein we report a practical pinacol coupling reaction, in which ketones (aldehydes) react smoothly with Sm and TMSBr to afford the diol products with Sm(II) or (III) siliyl species generated in situ. This reported method affords poor yields for aromatic ketone substrates and good yields for aliphatic ketones. Therefore, it distinguishes from most reductive coupling approaches that are more effective for aromatic carbonyl compounds and provides a facile and robust approach for the pinacol coupling of aliphatic ketones. Mechanistic studies also indicated the pinacolization probably proceeded via an anionic instead of radical coupling pathway involving the Brook rearrangement in the presence of samarium (II or III) silyl species.

This paper discovers and reveals a phenomenon of feigned death induced by partial delithiation in silicon composite electrodes. Unexpected extremely rapid capacity fading occurs in the initial dozens of the cycles with low upper cut-off voltages. By looking into the irreversibility, the crack, the elemental analysis and the thickness/weight of the electrode, it suggests that the rapid capacity fading is not induced by degradation. Additionally, by providing a reboot with full delithiation, the capacity can be recovered completely, which confirms the integrity of the electrode. This novel type of capacity fading is named by “feigned death” to distinguish it from the “true death” caused by degradation. It is further confirmed that the feigned death is caused by the asymmetric phase transformation between crystalline and amorphous phases in silicon electrodes. When the depth of lithiation is high enough to generate the c-Li3.75Si phase but the depth of delithiation is too low to eliminate the generated crystalline phase, the feigned death is triggered. The findings of this work provide an in-depth understanding of the electrochemical performance of Si-based electrodes.

A metal-free and highly efficient catalytic system involving a task-specific ionic liquid, [P4444][p-2-O], and a pyrene-based conjugated polymer was developed for direct CO2 capture from air and its further photoreduction to CO under visible light irradiation, affording a CO production rate of 47.37 μmol g−1 h−1 with a selectivity of 98.3%.

Mesoporous Troger's base-functionalized polymers (Meso-TBPs) were prepared using a sulfonic acid group functionalized ionic liquid/H2O system, with surface areas up to 431 m2 g−1 and pore sizes of 3–15 nm. Ir(II) coordinated Meso-TBPs exhibited extraordinary catalytic performance in the N-methylation of amines using methanol.

The chemical transformation of atmospheric CO2 is of great significance yet still poses a great challenge. Herein, azole-anion-based aprotic ionic liquids (ILs) were synthesized by the deprotonation of weak proton donors (e.g., 2-methylimidazole, 4-methylimidazole, and 2,4-dimethylimidazole) with tetrabutylphosphonium hydroxide, [Bu4P][OH]. We found that these ILs, such as [Bu4P][2-MIm], could activate atmospheric CO2 through the formation of carbamates. The resultant carbamate intermediates could further react with various types of substrate, including propargylic alcohols, 2-aminobenzonitriles, ortho-phenylenediamines, and 2-aminothiophenol, thereby producing α-alkylidene cyclic carbonates, quinazoline-2,4(1 H,3 H)-diones, benzimidazolones, and benzothiazoline, respectively, in moderate-to-good yields. Thus, we have achieved the transformation of CO2 at atmospheric pressure, and we expect this method to open up new routes for the synthesis of various oxygen-containing heterocyclic compounds under metal-free conditions.

The synthesis of hierarchically mesoporous polymers with multiple functionalities is challenging. Herein we reported a template-free strategy for synthesis of phenolic azo-polymers with hierarchical porous structures based on diazo-coupling reaction in aqueous solution under mild conditions. The resultant polymers have surface areas up to 593 m(2) g(-1) with the mesopore ratio of80 %, and a good ability to complex with metal ions, such as Cu(2+) , Zn(2+) ,Ni(2+) , achieving a metal loading up to 26.24 wt %. Moreover, the polymers complexed with Zn showed excellent performance for catalyzing the reaction of CO2 with epoxide, affording a TOF of 2570 h(-1) in the presence of tetrabutyl ammonium bromide (7.2 mol %). The polymer complexed with Cu could catalyze the oxidation of alcohol with high efficiency.

End groups in small-molecule photovoltaic materials are important owing to their strong influence on molecular stability, solubility, energy levels, and aggregation behaviors. In this work, a series of donor-acceptor pentads (D2 -A-D1 -A-D2 ) were designed and synthesized, aiming to investigate the effect of the end groups on the materials properties and photovoltaic device performance. These molecules share identical central A-D1 -A triads (with benzodithiophene as D1 and 6-carbonyl-thieno[3,4-b]thiophene as A), but with various D2 end groups composed of alkyl-substituted thiophene (T), thieno[3,2-b]thiophene (TT), and 2,2'-bithiophene (BT). The results indicate a relationship between conjugated segment/alkyl chain length of the end groups and the photovoltaic performance, which contributes to the evolving molecular design principles for high efficiency organic solar cells.

Visible-light-driven photoreduction of CO2 to energy-rich chemicals in the presence of H2 O without any sacrifice reagent is of significance, but challenging. Herein, Eosin Y-functionalized porous polymers (PEosinY-N, N=1-3), with high surface areas up to 610 m2 g-1 , are reported. They exhibit high activity for the photocatalytic reduction of CO2 to CO in the presence of gaseous H2 O, without any photosensitizer or sacrifice reagent, and under visible-light irradiation. Especially, PEosinY-1 derived from coupling of Eosin Y with 1,4-diethynylbenzene shows the best performance for the CO2 photoreduction, affording CO as the sole carbonaceous product with a production rate of 33 μmol g-1 h-1 and a selectivity of 92 %. This work provides new insight for designing and fabricating photocatalytically active polymers with high efficiency for solar-energy conversion.

B(C6F5)3 combined with atmospheric CO2 was found to be highly effective for the cyclization of ortho-substituted aniline derivatives with N,N-dimethylformamide (DMF), and a series of N-containing heterocycles including benzothiazoles, benzimidazoles, quinazolinone and benzoxazole were obtained in good to excellent yields.

A novel bathocuproine (BCP) derivative 4,7-bis(3,5-bis(trifluoromethyl)phenyl)-2,9-dimethyl-1,10-phenanthroline (BCP-2CF3) was synthesized and investigated as a candidate for exciton blocking layers (EBLs) in organic solar cells. The impacts of BCP-2CF3 and BCP on the performance of photovoltaic devices were studied for bulk-heterojunction (BHJ) devices with a blend of poly[N-9′′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) and [6,6]phenyl-C61-butyric acid methyl ester (PC61BM). In comparison with BCP, BCP-2CF3 showed a comparable improvement in the power conversion efficiency (PCE) (ca. 39%), and moreover a better thermal stability. Organic photovoltaic (OPV) devices with BCP-2CF3 withstood an annealing temperature as high as 100 °C, while those with BCP revealed a loss about 90% of the original efficiency at the same temperature. The newly designed principle for BCP-derived EBL materials opens a window for systematic enhancement of the efficiency and especially durability of organic solar cells.

The fabrication of printed high-performance and environmentally stable n-type single-walled carbon nanotube (SWCNT) transistors and their integration into complementary (i.e., complementary metal–oxide–semiconductor, CMOS) circuits are widely recognized as key to achieving the full potential of carbon nanotube electronics. Here, we report a simple, efficient, and robust method to convert the polarity of SWCNT thin-film transistors (TFTs) using cheap and readily available ethanolamine as an electron doping agent. Printed p-type bottom-gate SWCNT TFTs can be selectively converted into n-type by deposition of ethanolamine inks on the transistor active region via aerosol jet printing. Resulted n-type TFTs show excellent electrical properties with an on/off ratio of 106, effective mobility up to 30 cm2 V–1 s–1, small hysteresis, and small subthreshold swing (90–140 mV dec–1), which are superior compared to the original p-type SWCNT devices. The n-type SWCNT TFTs also show good stability in air, and any deterio...

In this article, the geometrical and electronic structures of a series of borepin and beryllepin transition-metal sandwich complexes M(C6H6R)2 (R = BH, Be; M = Cr, Mo, W) have been systematically investigated at the B3LYP and BP86 levels of theory. Comparing to Cr(C6H6)2, the optimized structures possess the relatively larger binding energies, similar HOMO-LUMO and fundamental gaps. The topology parameters and energy decomposition analyses show the M-C6H6R bonding interactions are mostly covalent bonds. The detailed molecular orbital and Adaptive Natural Density Partitioning analyses indicate that the spd-π interaction plays an important role in stabilizing M(C6H6R)2. Nucleus independent chemical shift (NICS) analysis indicates the aromaticity of the C6H7B/C6H6Be ligands is strengthened by the metal atoms in the sandwich complexes M(C6H6R)2. Based on the negative free energy changes of the reactions of the C6H7B/C6H6Be ligands with M(C6H6)2, the concerned borepin and beryllepin sandwich complexes probably are synthesized in gas phases.

LiNi0.6Mn0.2Co0.2O2 attracts increasing attention in industry due to its high energy density. Vinylene carbonate and 1,3-propane sultone are engaged to enhance the high-temperature performance of LiNi0.6Mn0.2Co0.2O2/artificial graphite pouch cells in this work. With the addition of the additives, the capacity retention of the full cell reaches 98% after 200 cycles at 45 °C and 500 mA. Meanwhile, the underneath mechanism is investigated by employing X-ray photoelectron spectroscopy, gas chromatograph-mass spectrometer and liquid chromatography-quadruple time of flight mass spectrometry measurements. The results show that the additives can not only protect the anode, but also shelter the cathode. It is of great interest that vinylene carbonate can suppress the decomposition of electrolyte, leading to less organic species in electrolyte, more stable interfaces. The addition of 1,3-propane sultone takes part in the generation of sulfonates after formation, which can be reduced to sulfides upon cycling. The combination of these two additives can optimize the interfacial reactions, as well as can suppress the decomposition of electrolytes and the dissolution of manganese, which leads to much better high-temperature storage performance and cycling performance of the full cells.

Uniform N-doped carbon nanotubes were obtained for the first time via a morphology-preserving thermal transformation of organic polymer nanotubes without any additional templates. These carbon nanotubes acted as a superior metal-free carbon catalyst for C–H arylation of benzene, reductive hydrogen atom transfer and oxidation reactions.

The high-quality graphene film can be grown on single-crystal Cu substrate by seamlessly stitching the aligned graphene domains. The roles of O2 and H2 have been intensively studied in the graphene growth kinetics, including lowering the nucleation sites and tailoring the domain structures. However, how the O2 and H2 influence Cu orientations during recrystallization prior to growing graphene, still remains unclear. Here we report that the oxidation of Cu surface tends to stabilize the Cu(001) orientation while impedes the evolution of Cu(111) single domain during annealing process. The crystal orientation-controlled synthesis of aligned graphene seeds is further realized on the long-range ordered Cu(111) substrate. With decreasing the thickness of oxide layer on Cu surface by introducing H2, the Cu(001) orientation changes into Cu(111) orientation. Meanwhile, the average domain size of Cu foils is increased from 50 μm to larger than 1000 μm. The density functional theory calculations reveal that the oxygen increases the energy barrier for Cu(111) surface and makes O/Cu(001) more stable than O/Cu(111) structure. Our work can be helpful for revealing the roles of O2 and H2 in controlling the formation of Cu single-crystal substrate as well as in growing high-quality graphene films.