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Anatase TiO2 is a promising anode material for sodium-ion batteries (SIBs). However, its sodium storage mechanisms in terms of crystal structure transformation during sodiation/de-sodiation processes are far from clear. Here, by analyzing the redox thermodynamics and kinetics under near-equilibrium states, we observe, for the first time, that upon Na-ion uptake, the anatase TiO2 undergoes a phase transition and then an irreversible crystal structure disintegration. Additionally, unlike previous theoretical studies which investigate only the two end points of the sodiation process (i.e., TiO2 and NaTiO2), we study the progressive crystal structure changes of anatase TiO2 upon step-by-step Na-ion uptake (NaxTiO2, x = 0.0625, 0.125, 0.25, 0.5, 0.75, and 1) for the first time. It is found that the anatase TiO2 goes through a thermodynamically unstable intermediate phase (Na0.25TiO2) before reaching crystalline NaTiO2, confirming the inevitable crystal structure disintegration during sodiation. These combined experimental and theoretical studies provide new insights into the sodium storage mechanisms of TiO2 and are expected to provide useful information for further improving the performance of TiO2-based anodes for SIB applications.

The LiF-rich solid electrolyte interphase (SEI) is an emerging research hotspot to improve battery performance. Its high Li-ion conductivity and high interfacial energy result in fast lithiation/de-lithiation in electrode materials while at the same time protect materials from pulverization. Currently, the developed LiF-rich SEI fabrication methods are based on electrolyte decomposition upon cycling, but so far have only been applied to Li metal or Si anodes. Furthermore, the influences of LiF on the electrochemical behavior of the electrolyte are not fully understood. Here, a new pre-coating approach is proposed to fabricate a conformal LiF layer on both anode and cathode materials (silicon suboxide (SiOx) and LiNi0.8Co0.1Mn0.1O2 (NCM811) as examples). LiF assisted the increase in the specific capacity of a SiOx electrode from 301 to 1034 mA h g−1 after 100 cycles at 500 mA g−1. In addition, a full cell assembled with a prepared anode (SiOG@LiF3) and cathode (NCM811@LiF3) showed outstanding cycling stability. Combining density functional theory (DFT) calculation with SEM and XPS characterization revealed for the first time that the pre-coating LiF layer had a strong preferential adsorption of LiPF6 molecules on the surface, leading to the formation of inorganic-rich SEI during cycling; thereby enabling a fast Li-ion uptake/removal process and improving the electrode integrity.

Maintaining the stability of tin halide perovskites is a major challenge in developing lead-free perovskite solar cells (PSCs). Adding extra SnX2 (X = F, Cl, or Br) in the precursor solution to inh...

Exploiting high-performance non-doped organic light-emitting diodes (OLEDs) is a step towards future commercial application requirements, but great challenges remain due to quenching related to intermolecular triplet interaction. In this work, a novel strategy of exploiting high-performance non-doped electroluminescence via tuning intermolecular hydrogen bonding is demonstrated. Suitable intermolecular hydrogen bonding enables formation of a 3D supramolecular framework, which not only evidently restricts the nonradiative process and suppresses the triplet exciton quenching caused by π–π stacking of triplets, but also favors the horizontal molecular orientations especially in their non-doped states. The non-doped OLED based on the thermally activated delayed fluorescence emitter mTPy-PXZ with such suitable intermolecular hydrogen bonds exhibits the state-of-the-art performance with maximum external quantum efficiency of up to 23.6% with only 7.2% roll-off at 1000 cd m−2. Moreover, it is the first report that the performance of an OLED with a non-doped emitting layer can surpass its corresponding optimized doped device. It is believed that this hydrogen bond-modulated mechanism can not only provide a new pathway for designing emitters for high-performance non-doped organic electroluminescence, but also has great potential in other solid-state luminescence applications.

The electrocatalytic nitrogen reduction reaction (e-NRR), an eco-friendly and economical approach to convert nitrogen to ammonia under mild conditions, has received widespread attention in recent years. Defect engineering has been illustrated to be an effective strategy to improve the catalytic activity and selectivity of electrocatalysts via changing the electronic states as well as creating additional active sites for reduction reactions. Thus far, various approaches have been adopted to tune the physical and chemical properties of catalyst materials by means of inducing defects of different types and varying their concentrations or locations in host materials. In this review, the mechanisms and design principles of defective electrocatalysts for the NRR are introduced, and the refined synthesis and characterization techniques of defect engineering are systematically summarized. Based on the recent advances in defect engineering of electrocatalysts for the NRR, the roles of various defect states, such as vacancies and the amorphous phase, in the catalytic enhancement mechanism are comprehensively discussed. Finally, perspectives on the challenges and opportunities in developing new cost-effective and high-efficiency NRR catalysts for practical applications are outlined.

(4 + 3) cycloadditions between allenyl ethers and furans are described. The reaction features an in situ formation of oxygen-stabilized oxyallyls via epoxidations of allenyl ethers in the presence of H2PO4−. The multiple interactions between the oxygen-stabilized oxyallyl species and H2PO4− were studied using DFT calculations for rationalization of the regio- and diastereoselectivity of this cycloaddition. The utilities of this cycloaddition have been demonstrated by converting the (4 + 3) cycloadduct into the cyclohepta[b]benzofuran skeleton of frondosin B in two steps.

Novel charge transport properties distinguished from their parental materials are intriguing features of charge transfer complexes (CTCs). In this work, co-evaporated molybdenum(VI)oxide and sexithiophene (MoO3 : 6T) CTC thin film is prepared and its electron and hole transport properties are studied. While the MoO3 : 6T CTC material shows both electron and hole transport, detailed changes in molecular orbital hybridization are further studied under an external stimulus. Using a simple rubbing process, the intermolecular interaction of the CTC material can be tuned such that changes in optical properties, vibrational modes, chemical states and electronic structures are observed. These changes in properties and charge transport behaviors enable us to understand the influences of CTC frontier molecular orbitals (FMOs) and their degree of coupling on the charge transport properties. This work provides insight into the understanding of the intermolecular interactions and their influence on the charge transport properties of thin film CTCs.

Bismuth (Bi) is a promising alloy-type material for potassium-ion batteries (KIBs). However, its large volume variation during the cycling process remains a great challenge to its practical application. Here, a one-step approach was developed to synthesize a novel Bi-based composite structure comprising Bi nanorod networks confined in a N, S co-doped carbon matrix (Bi∈NS–C). As an anode, the Bi∈NS–C structure successfully integrated the merits of the micro-sized N, S co-doped carbon matrix, which functioned concurrently as a conductive framework and a robust buffer for large volume variation, and the network structure of Bi nanorods which enhanced the reaction kinetics and accommodated the large strain originating from the alloying/dealloying process. As a result, the Bi∈NS–C electrodes exhibited an excellent overall performance, i.e., high rate capabilities of 338 mA h g−1 and 289 mA h g−1 at current densities of 0.5 and 6 A g−1, respectively, and outstanding long-term cycling stability with 91% capacity retention at 5 A g−1 after 1000 cycles. Furthermore, a full KIB with hexacyanoferrate as the cathode and Bi∈NSC as the anode was assembled, which was demonstrated to be able to deliver a decent energy density of 295 W h kg−1 and superior cycling stability with 83% capacity retention after 800 cycles.

Synthesis of the multidentate coordinated chelate N3C–H2, composed of a linked functional pyridyl pyrazole fragment plus a peripheral phenyl and pyridyl unit, was obtained using a multistep protoco...

Room temperature aerobic oxidation of hydrocarbons is highly desirable and remains a great challenge. Here we report a series of highly electrophilic cobalt(III) alkylperoxo complexes, CoIII(qpy)OOR supported by a planar tetradentate quaterpyridine ligand that can directly abstract H atoms from hydrocarbons (R'H) at ambient conditions (CoIII(qpy)OOR + R'H → CoII(qpy) + R'• + ROOH). The resulting alkyl radical (R'•) reacts rapidly with O2 to form alkylperoxy radical (R'OO•), which is efficiently scavenged by CoII(qpy) to give CoIII(qpy)OOR' (CoII(qpy) + R'OO• → CoIII(qpy)OOR'). This unique reactivity enables CoIII(qpy)OOR to function as efficient catalysts for aerobic peroxidation of hydrocarbons (R'H + O2 → R'OOH) under 1 atm air and at room temperature.

Solar steam generation is considered as an efficient way for addressing water shortage issues via seawater desalination and wastewater purification. In a solar evaporator, an absorber would convert optical energy to heat for evaporating nearby water. In this process, many low-boiling-point contaminants can also be evaporated along with water steam, which compromises the effectiveness of purification. There is, so far, no study on the removal of such low-boiling-point contaminants such as organic pesticides in wastewater. To address this problem, we demonstrate a versatile carbon hybrid aerogel (CHA) as a solar powered water purification platform. With an elaborate absorber design, the maximum solar evaporation rate of 2.1 kg m-2 h-1 is achieved under 1 sun illumination. More importantly, CHA can effectively suppress the evaporation of low-boiling-point contaminants including common pesticides and mercury ion via its strong adsorption and retention effect. Synergetic steaming and the adsorption of CHA will inspire more paradigms of solar steam generation technologies for applications relevant to detoxification and water remediation.

Single atom catalysts have received widespread attention for their fascinating performance in terms of metal atom efficiency as well as their unique catalysis mechanisms comparing to conventional catalysts. Here, we prepared a high-performance catalyst of single-Cu-atom-decorated boron nitride nanofibers (BNNF-Cu) via a facile calcination method for the first time. The as-prepared catalyst shows excellent catalytic activity and good stability for converting different nitro compounds into their corresponding amines both with and without photoexcitation. By combined studies using synchrotron radiation analysis, high-resolution high-angle annular dark-field transmission electron microscopy studies and DFT calculation, dispersion and coordination of Cu atoms as well as their catalytic mechanisms are explored. The BNNF-Cu catalyst is found to have a record high turn-over frequency comparing to previously reported nonprecious-metal-based catalysts. While the performance of the BNNF-Cu catalyst is only of the middle range level among the state-of-the-art precious-metal-based catalysts, due to the much lower cost of the BNNF-Cu catalyst, its cost-efficiency is the highest among these catalysts. This work provides a new choice of support material which can promote the development of single atoms catalysts.

Many experiments have been carried out on the (16.8 kJ, 17 kV) dense plasma focus PF-24 device operated with pure deuterium and deuterium-argon admixture. The main purpose of the work was to investigate the influence of the doping argon on the average total neutron yields experimentally and numerically. The 103 discharges (34 for D2, 69 for D2- $x$ %Ar, where $x = 3, 5, 10, 15, 22, 25, 30, 45, 60$ ) were performed in four experimental sessions under constant total initial optimum pressure of about 2.2 torr. The total current and its time derivative traces, as well as the total neutron yield values, were recorded, and the electro-kinetic plasma parameters were estimated for each shot. The Lee model has also been adapted for gas mixture plasma focus modeling, and then the enhanced code was used for simulation of each of the PF-24 discharge with D2 and D2- $x$ %Ar. The fitting parameters for each shot are found and discussed. The measured and computed values of the neutron yield and the electro-kinetic plasma parameters are in good agreement. The obtained results showed that there is no neutron yield enhancement with argon seeding. The scaling law of the neutron yield $Y_{n}$ against argon fraction has been deduced. Additionally, our results illustrate that the PF-24 plasma focus device has an optimized configuration for the DD fusion neutron emission.

Bis-tridentate Ir(III) metal complexes bring forth interesting photophysical properties, among which the orthogonal arranged, planar tridentate chelates could increase the emission efficiency due to the greater rigidity and, in the meantime, allow strong interligand stacking that could deteriorate the emission efficiency. We bypassed this hurdle by design of five bis-tridentate Ir(III) complexes (-), to which both of their monoanionic ancillary and dianionic chromophoric chelate were functionalized derivative of 2-pyrazolyl-6-phenylpyridine, i.e. pzpyphH parent chelate. Hence, addition of phenyl substituent to the pyrazolyl fragment of pzpyphH gave rise to the precursors of monoanionic chelate (A1H-A3H), on which the additional -butyl and/or methoxy groups were introduced at the selected positions for tuning their steric and electronic properties, while precursors of dianionic chelates was judiciously prepared with an isoquniolinyl central unit on pziqphH in giving the red-shifted emission (cf. L1H and L2H). Factors affected their photophysical properties were discussed by theoretical methods based on DFT and TD-DFT calculation, confirming that the T excited state of all investigated Ir(III) complexes shows a mixed metal-to-ligand charge transfer (MLCT), intraligand charge transfer (ILCT), ligand-to-ligand charge transfer (LLCT), and ligand-centered (LC) transition character. In contrast, the poor quantum yield of is due to the facilitation of the nonradiative decay in comparison to the radiative process. As for potential OLED applications, Ir(III) complex gives superior performance with max. efficiencies of 28.17%, 41.25 cd·A and 37.03 lm·W, CIE = 0.63, 0.37 at 50 mA cm, and small efficiency roll-off.

Hierarchical ZnCo2O4 particles hosted by 3D graphene network were synthesized through a one-pot hydrothermal synthesis approach. The as-synthesized ZnCo2O4-graphene composites showed an outstanding overall electrochemical performance as an anode of lithium ion batteries with high specific capacity and excellent cycling stability, i.e., a reversible capacity of 1920 mAh g−1 at a current density of 1000 mA g−1 after 300 cycles. In particular, at an elevated current density of 4000 mA g−1, a high capacity of 1100 mAh g−1 could still be achieved, and it dropped by only 34% to 730 mAh g−1 after 2000 cycles. The synergistic roles of the hierarchically nanostructured ZnCo2O4 and highly-conductive 3D graphene networks in improving the specific capacity, rate performance, and cycling stability were discussed.

This paper shows the correlation of the characteristic Ne soft X-ray (SXR) signal pulse with computed dynamics of the plasma focus using doped neon in Ne (97.5%)/Kr (2.5%) admixtures. The Lee model code is coupled with a specifically designed correlation excel template. The results show that typically, the characteristic Ne SXR pulse signal starts after the start of the reflected shock (RS) and before the beginning of the pinch. Specifically, in the illustrated shot, the RS phase starts at $3.375~\mu \text{s}$ while the pinch phase starts at $3.384~\mu \text{s}$ . The characteristic Ne SXR signal pulse starts at $3.377~\mu \text{s}$ , which is 2 ns after the start of the RS and 7 ns before the pinch starts. There is a consistent trend of Ne SXR correlation with the computed dynamics in the Ne doped with Kr admixtures up to a doping level of 2.5%.

Over the last few years, numerous efforts have been made to develop white light emitting metal–organic frameworks (MOFs), due to the useful features of MOFs such as ultrahigh surface areas and tunable pore architecture. However, rare earth (RE) ions are most commonly applied as phosphors in these materials so far, raising device cost and environmental concerns. Here, we designed a new type of RE-free material capable of white light emission upon excitation at 365 nm, with the photoluminescence quantum yield in the solid state reaching 37%, fabricated by compositing carbon dots (CDs) with a Zr(IV)-based MOF. WLEDs constructed by depositing the CDs/Zr-MOF nanocomposite on a commercial UV LED chip feature CIE chromaticity coordinates of (0.31, 0.34), a high color rendering index (CRI) of 82, and a luminous efficiency of 1.7 lm W−1.

Two microporous anionic indium-based metal–organic frameworks, namely [Me2NH2][In(abtc)]·solvents (1) and [Me2NH2][In(bptc)]·solvents (2) (H4abtc = 3,3′,5,5′-azobenzenetetracarboxylic acid; H4bptc = biphenyl-3,3′,5,5′-tetracarboxylic acid), have been synthesized and characterized. Single-crystal X-ray analyses show that compounds 1 and 2 display isostructural three-dimensional anionic frameworks with PtS topology. With these structural features, both compound 1 and compound 2 can selectively separate cationic organic dyes with suitable size. White-light emission can be obtained by loading compound 2 with safranin O. In addition, compound 1 dispersed in dimethyl formamide not only retains the emission of the abtc4− ligand at about 402 nm, but also gives new emission centered at 623 nm. Based on these emissions, compound 1 was developed as an efficient dual-emitting sensor for probing Fe3+ ions.

Tin-based perovskites with excellent optoelectronic properties and suitable band gaps are promising candidates for the preparation of efficient lead-free perovskite solar cells (PSCs). However, it is challenging to prepare highly stable and efficient tin-based PSCs because Sn2+ in perovskites can be easily oxidized to Sn4+ upon air exposure. Here we report the fabrication of air-stable FASnI3 solar cells by introducing hydroxybenzene sulfonic acid or its salt as an antioxidant additive into the perovskite precursor solution along with excess SnCl2 . The interaction between the sulfonate group and the Sn2+ ion enables the in situ encapsulation of the perovskite grains with a SnCl2 -additive complex layer, which results in greatly enhanced oxidation stability of the perovskite film. The corresponding PSCs are able to maintain 80 % of the efficiency over 500 h upon air exposure without encapsulation, which is over ten times longer than the best result reported previously. Our results suggest a possible strategy for the future design of efficient and stable tin-based PSCs.

While sodium metal anodes (SMAs) feature many performance advantages in sodium ion batteries (SIBs), severe safety concerns remain for using bulk sodium electrodes. Herein, a 3D Ag@C natrophilic substrate prepared by a facile thermal evaporation deposition method, which can be employed as a much safer "anode-free" SMA, is reported. Initially, there is no bulk sodium on the Ag@C substrate in the assembled SIBs. Upon charging, sodium will be uniformly deposited onto the Ag@C substrate and afterwards functions as a real SMA, thus inheriting the intrinsic merits of SMA and enhancing safety simultaneously. While cycling, the as-synthesized substrate demonstrates superior sodium plating/stripping cycling stability at 1, 2 and 3 mA cm

Atomic lattice reconstruction and postcrack edge stacking behavior are observed during the fracture of 2D ReS2., Low-dimensional materials usually exhibit mechanical properties from those of their bulk counterparts. Here, we show in two-dimensional (2D) rhenium disulfide (ReS2) that the fracture processes are dominated by a variety of previously unidentified phenomena, which are not present in bulk materials. Through direct transmission electron microscopy observations at the atomic scale, the structures close to the brittle crack tip zones are clearly revealed. Notably, the lattice reconstructions initiated at the postcrack edges can impose additional strain on the crack tips, modifying the fracture toughness of this material. Moreover, the monatomic thickness allows the restacking of postcrack edges in the shear strain–dominated cracks, which is potentially useful for the rational design of 2D stacking contacts in atomic width. Our studies provide critical insights into the atomistic processes of fracture and unveil the origin of the brittleness in the 2D materials.

A water-soluble europium complex (EuL1), with the chromophore conjugated with both the Eu3+ ion and the aza-18-crown-6 ether moiety (receptor), were synthesized and its photophysical properties were studied. Saxitoxin (STX) selectively binds to EuL1 and induced a 4-fold enhancement in europium emission in the presence of a variety of metal ions. A mechanistic study indicated that the luminescence enhancement could be triggered by a two-interaction binding mechanism, in which the initial interaction between STX and the aza-18-crown-6 ether moiety of EuL1 induces the secondary interactions between STX and the Eu3+ ion, which resulted in displacement of the coordinated water molecule on Eu3+ ion.

Stabilization of two-dimensional (2D) PEA2PbI4 (PEA is phenethylammonium) perovskite nanocrystals (PNCs) in water is achieved. By inhibiting the desorption process, the PNCs show exceptional stability for more than 2 months in PEA+ aqueous solutions. Stabilized PNCs are successfully applied for probing Cu2+ in aqueous solution.

The measured current waveforms of PF1000 plasma focus operating in neon are first fitted to the computed currents using the Lee model for the pressures of 0.5 and 0.8 torr. The fitting fixes the model parameters. The code is then run to study and to optimize the soft X-ray yield from (~352 kJ) PF1000 device. The maximum characteristic soft X-ray (H-like and He-like lines) yield of 4.2 kJ is found to occur at the pressure of 0.85 torr, with the pinch duration of 207 ns and with an all-line yield of 4.8 kJ. Maximum compression (corresponding to smallest pinch radius) of 0.585 cm with the duration of 224 ns is obtained at 1 torr with the greatest all-line yield of 7.1 kJ but a lower characteristic soft X-ray yield of 3.2 kJ. Detailed computation results indicate that the maximum compression (minimum pinch radius) at 1 torr is attributed to two mechanisms: thermodynamics specific heat ratio effects and radiative losses.

In this work, damage results of four 12 mm × 12 mm × 5 mm PLANSEE double forged tungsten target samples exposed in INTI PF device at different distances from anode operating in the fast focus mode at 12 kV, 2.5 Torr deuterium are presented. SEM and EDX images and analysis show the extent of damage on the exposed tungsten surface. Micro-cracks up to 300 nm and 500 nm to 5 μm holes together with signs of melting are found on the tungsten exposed surfaces depending on their distances from the anode top. Current waveforms fitting using Lee Model Code show yields of 3 × 106 neutrons and 8.5 × 1014 ions per shot with average ion energy of 56 keV per ion at pinch exit, generating heat flux of 1.8 × 1014 Wm−2 and damage factor (also called heat flux factor) of 1.6 × 1010 Wm−2s0.5 on a target at pinch exit.

Copper is vital to many physiological activities, and its dyshomeostasis is related to cancers as well as neurodegenerative diseases. Copper targeting probes with single imaging modality have been extensively reported and employed in specific aspects. Herein, we delineate the development of Cu(II)-specific multi-functional imaging probes based on a fluorinated azine FN. The azine selectively binds to a Cu2+ ion, forming a 1:1 FN-Cu2+ complex, and induces a substantial fluorescence quenching, which can be resumed upon addition of H2S (Na2S as the source of H2S). The binding of the paramagnetic Cu2+ ions also leads to the relaxation enhancement of the 19F nuclei in the FN-Cu2+ complex and improve the signal-to-noise ratio of the phantom images. The 18F-radiolabeled analogue, [18F]FN, is synthesized for the first time and used in PET/CT imaging on cynomolgus for a preliminary study of pharmacokinetics.

The rational design of high-performance electrocatalysts based on nonprecious metals is a key for the development of water-splitting technology. In this work, porous nickel-cobalt nitride–oxide (NiCo–N–O) nanosheet hybrids in a networked configuration are synthesized on carbon cloth through in situ plasma treatment of nickel-cobalt layered double hydroxide (LDH) precursors. The self-supported NiCo–N–O electrodes exhibit the outstanding catalytic activity of hydrogen evolution reaction (HER) with a low overpotential of 50 mV at 10 mA cm−2 in alkaline conditions. The synergistic effects of the morphology, microstructure, and electron transfer between nickel-cobalt nitride and oxide and the favorable role of introducing bimetallic Ni and Co sites on the enhanced electrocatalytic activities are discussed. This work provides a simple and feasible pathway to prepare porous bimetal nitride–oxide hybrid HER electrocatalysts with high efficiency and stability.

Novel bis-tridentate Ir(III) complexes are of great interest in the development of blue-emitting organic light-emitting diodes (OLEDs) due to their rigid and robust molecular architecture. In this work, both the functional 6-pyrazolyl-2-phenoxypyridine (pzyPx) and 6-(1,2,4-triazolyl)-2-phenoxypyridine (tazPx) were used as chromophoric chelates in the construction of the blue-emitting Ir(III) phosphors. Accordingly, the substitution of pzyPx with tazPx chelates retains the desired characteristics, i.e. both high quantum yields (>92%) in solution and shortened radiative lifetime (τrad) (from 19.8 to 2.5 μs), respectively. The theoretical calculation reveals that the triazolate moiety contributes considerably to the radiative transition, to which the greater iridium involvement in T1 → S0 transition of tazPx-based complex is responsible for the shortened τrad. Consequently, enhanced photostabilities in degassed toluene and competitive performances with maximum EQE of 19.2% with CIE coordinates of (0.17, 0.22) were observed from the tazPx-based complex Px-33.

Covalent organic polymers (COPs) or covalent organic frameworks (COFs) are emerging types of electrode materials for electrochemical CO2 reduction reaction (CO2RR) owing to their controllable structures at the molecular level. However, their activities are often limited by stacking structures and low conductivities. Here we report an ultrathin cobalt tetraamino phthalocyanine-squaraine based COPs (COP-SA) for high-performance CO2RR towards CO. The extended π-conjugated skeleton constitutes the layer, and the zwitterionic structure from the squaraine unit helps the dispersion of layers, leading to an ultrathin thickness of ∼1.7 nm. The ultrathin nanostructure avoids the common agglomeration issues for molecular catalysts and thick nanomaterials, which is beneficial to afford highly exposed active sites and efficient electron transfer for electrochemical reactions. Theoretical calculation suggests that the squaraine unit will enhance the COOH adsorption and favor the CO desorption. These collectively conduce to a high current density of 9.74 mA cm−2 with 96.5 % CO faradaic efficiency, a large turnover frequency of 46 s-1 (by total cobalt site) at -0.65 V vs RHE and excellent cycling stability. This work underscores the structural and electronic effects for the rational design of ultrathin COPs materials for electrochemical CO2RR.

Double-shelled copper chalcogenide (Cu 2−x Se and Cu 7 S 4 ) nanocages of about 250 nm sizes are synthesized respectively by using Cu 2 O nanocubes as sacrificial precursor via Kirkendall diffusion and etching. Both the double-shelled Cu 2−x Se and Cu 7 S 4 nanocages are demonstrated to be excellent counter electrode (CE) materials in quantum dot-sensitized solar cells (QDSSCs) and exhibit high electrocatalytic activities for polysulfide electrolyte regeneration. The QDSSCs using the double-shelled Cu 2−x Se and Cu 7 S 4 nanocages as CEs show power conversion efficiencies (PECs) of 4.76 and 4.53%, respectively, which are 19.6% and 15.3% higher than the corresponding devices using the single-shelled Cu 2−x Se and Cu 7 S 4 nanocages as CEs. The overall enhancement of photovoltaic performance including the fill factor, short-circuit current density and PEC is attributed to the larger CE-electrolyte interface provided by the double-shelled nanocages facilitating fast electron transfer in the QDSSCs.

Measured current waveforms at different neon pressures from two different plasma focus (PF) devices, namely, NX2 and NX1 are used for analysis using the Lee code. The model parameters of mass ( $f_{m}$ and $f_{{\text {mr}}}$ ) and current ( $f_{\text {c}}$ and $f_{\mathrm {cr}}$ ) in axial and radial phase, respectively, are obtained by fitting the computed current waveform to the measured current waveform for each pressure over a range of pressures in neon. The results show that the value of $f_{m}$ and $f_{\mathrm {mr}}$ ranges from 0.07 to 0.12 and 0.09 to 0.20, respectively, over the pressure range 1.0–5.0 Torr for NX2, whereas for NX1 it ranges from 0.020 to 0.024 and 0.048 to 0.08, respectively, over the pressure range 7.5–12 Torr. In all cases, the values of $f_{c}$ and $f_{\mathrm {cr}}$ are fixed at 0.7. Comparison of computed and measured soft X-ray (SXR) yield using fit model parameters for both devices shows good agreement. An important finding is that despite the noticeable variation of mass factors over the whole pressure range, a representative set of model parameters is found for each machine which may be taken as fixed over the range of pressures producing a good yield. In particular, for a high-performance PF using conventional electrode structure the representative set is: $f_{m} = 0.075$ , $f_{c} \,\, = \,\, 0.7$ , $f_{\mathrm {mr}} =0.1$ , and $f_{\mathrm {cr}}= \,\, 0.7$ . This is valuable information for neon SXR design purposes.

One important challenge in dye-sensitized solar cells (DSSCs) is to design and construct low-cost counter electrodes (CEs) with good electrocatalytic performance. In this work, a one-step solvothermal method was used to prepare cobalt-nickel (Co-Ni) based ternary selenides with different Co and Ni ratios. Co-Ni based ternary selenide films were fabricated by simple spray deposition for applications as low-cost and high-performance CEs in DSSCs. Electrochemical measurements demonstrate that the Co-Ni based ternary selenide CEs exhibit high electrocatalytic activity and strong charge-transfer ability for the reduction of I 3 − due to the synergistic effect between Co and Ni ions in Co-Ni based ternary selenides. In particular, Co 0.42 Ni 0.58 Se CE shows the higher electrocatalytic activity than other Co-Ni based ternary selenide CEs and platinum (Pt) CE. Furthermore, the DSSC with Co 0.42 Ni 0.58 Se CE exhibits photoelectrical conversion efficiency (PCE) of 6.15%, which is considerably higher than that of the DSSC with Pt CE (5.53%).

Ruthenium(II) tris(bipyridyl) cationic complex (Ru(bpy)32+) incorporated UiO-67 (Universitetet i Oslo) nanoscale metal–organic frameworks (NMOFs) with an average diameter of ∼92 nm were developed as theranostic nanoplatform for in vitro two-photon fluorescence imaging and photodynamic therapy. After incorporation into porous UiO-67 nanoparticles, the quantum yield, luminescence lifetime, and two-photon fluorescence intensity of Ru(bpy)32+ guest molecules were much improved owing to the steric confinement effect of MOF pores. Benefiting from these merits, the as-synthesized nanoparticles managed to be internalized by A549 cells while providing excellent red fluorescence in cytoplasm upon excitation with 880 nm irradiation. Photodynamic therapeutic application of the Ru(bpy)32+-incorporated UiO-67 NMOFs was investigated in vitro. The Ru(bpy)32+-incorporated UiO-67 NMOFs exhibited good biocompatibility without irradiation while having good cell-killing rates upon irradiation. In view of these facts, the deve...

Green synthesis of Cu2ZnSnS4 (CZTS) and Cu2ZnSn(S1−xSex)4 (CZTSSe) nanocrystals is highly desirable for low-cost and high-efficiency solar energy conversion devices. In this work, scalable synthesis of multinary CZTS and CZTSSe nanocrystals at room temperature has been achieved by a simple metal complex solution mixing (Metcomix) process. In the Metcomix process, CZTS or CZTSSe nanocrystals are formed by simply mixing aqueous solutions of copper thiourea complex ([Cu(TU)4]2+), zinc ammonium complex ([Zn(NH3)4]2+) and tin chalcogen complex ([Sn2S6]4−) or tin double chalcogen complex ([Sn2S4Se2]4−) at room temperature. The Metcomix process features low-energy-consuming, low-cost, environmentally friendly, high-purity, and scalable-production. The CZTS and CZTSSe nanocrystals have a small size of 4–10 nm and exhibit remarkable room-temperature photoluminescence and optical absorption properties. The CZTS and CZTSSe nanocrystals are also deposited onto ZnO nanorod arrays and demonstrated as efficient photoanodes for photoelectrochemical water splitting. The ZnO/CZTSSe photoanode exhibits a photocurrent density of 9.06 mA cm−2 at 1.23 V (vs. the NHE) and an optimal applied bias photon-to-current efficiency (ABPE) of ∼3.43% at a bias of 0.60 V. The present work demonstrates a new approach for synthesizing eco-friendly multinary chalcogenide nanocrystals at room temperature and their promising applications in solar energy conversion devices.

The development of nanoscaled theranostic agents for cancer combination therapies has received intensive attention in recent years. In this report, a degradable hollow mesoporous PEG-Si/C-DOX NP is designed and fabricated for pH-responsive, photoacoustic imaging-guided highly effective chemo-thermal combination therapy. The intrinsic hollow mesoporous structure endows the as-synthesized nanoparticles (NPs) with a high drug loading capacity (31.1%). Under NIR (808 nm) irradiation, the photothermal conversion efficiency of the Si/C NPs is as high as 40.7%. Preferential accumulation of the PEG-Si/C-DOX NPs around tumor tissue was demonstrated with photoacoustic images. Cellular internalization of the NPs and release of the DOX in nuclei are shown with fluorescent images. With efficient NIR photothermal conversion and high DOX loading capacity, the PEG-Si/C-DOX NPs are demonstrated to have remarkable cancer-cell-killing ability and to achieve complete in vivo tumor elimination via combinational chemo-thermal therapy. Last but not least, the NPs show good biodegradability and biosafety, making them a promising candidate for multifunctional drug delivery and cancer theranostic.

S-Doped 2H-MoSe2 (i.e., 2H-MoS2xSe2−2x) mesoporous nanospheres assembled from several-layered nanosheets are synthesized by sulfurizing freshly-prepared 1T-MoSe2 nanospheres, and they serve as a robust host material for sodium storage. The sulfuration treatment is found to be beneficial for removing surface/interface insulating organic contaminants and converting the 1T phase to the 2H phase with improved crystallinity and electrical conductivity. These result in significantly enhanced sodium storage performance, including charge/discharge capacity, first Coulombic efficiency, cycling stability, and rate capability. Coupled with benefits from in situ carbon modification and its mesoporous morphology, the 2H-MoS2xSe2−2x (x = 0.22) nanosphere anode can maintain a reversible capacity of 407 mA h g−1 after 100 cycles with no observable capacity fading at a high current density of 2.0 A g−1. This value is much higher than those of the anode fabricated with the freshly-prepared 1T-MoSe2 (95 mA h g−1) and the annealed 2H-MoSe2 (144 mA h g−1) samples. As the current density rises from 0.05 to 5.0 A g−1 (100-fold increase), the discharge capacity retention is significantly increased from 39% before sulfuration to 65% after sulfuration. This superior electrochemical performance of the 2H-MoS2xSe2−2x electrode suggests a promising way to design advanced sodium host materials by surface/interface engineering.

Metal organic frameworks (MOFs) are convenient precursors for preparing porous structures. In this work, the Prussian Blue (one kind of MOFs) is reacted with Zn acetate under microwave irradiation, forming hydroxides and carbonates nanosheets on the surface of Prussian Blue. After pyrolysis, a composite of ZnO/ZnFe 2 O 4 porous nanoparticles was obtained and applied as anode material for lithium ion batteries. The composite shows a good capacity of 804 mAh g −1 for 500 cycles at a current density of 1000 mA g −1 .

Cu–Ni–Mn-based ternary P2-type NaxCu0.15Ni0.20Mn0.65O2 (x = 0.50, 0.67, and 0.75) cathodes for sodium-ion batteries (SIBs) are synthesized by a co-precipitation method. We find that Na content plays a key role on the structure, morphology, and the charge–discharge performances of these materials. For x = 0.67 and 0.75, superstructure from Na+-vacancy ordering is observed, while it is absent in the x = 0.50 sample. Despite the same synthesis conditions, materials with x = 0.67 and 0.75 show smaller particle sizes compared to that of the x = 0.50 sample. In addition, redox potentials of the materials differ significantly even though they have the same transition metal ratios. These differences are attributed to the changes in local structures of the as-prepared materials arising from the different amount of Na and possibly oxygen in the lattice. Materials with x = 0.67 and 0.75 show excellent rate performance and cycle stability when tested as cathode material of SIBs. Average discharge potential is as high...

Nanoscale surface-engineering plays an important role in improving the performance of battery electrodes. Nb2 O5 is one typical model anode material with promising high-rate lithium storage. However, its modest reaction kinetics and low electrical conductivity obstruct the efficient storage of larger ions of sodium or potassium. In this work, partially surface-amorphized and defect-rich black niobium oxide@graphene (black Nb2 O5-x @rGO) nanosheets are designed to overcome the above Na/K storage problems. The black Nb2 O5-x @rGO nanosheets electrodes deliver a high-rate Na and K storage capacity (123 and 73 mAh g-1 , respectively at 3 A g-1 ) with long-term cycling stability. Besides, both Na-ion and K-ion full batteries based on black Nb2 O5-x @rGO nanosheets anodes and vanadate-based cathodes (Na0.33 V2 O5 and K0.5 V2 O5 for Na-ion and K-ion full batteries, respectively) demonstrate promising rate and cycling performance. Notably, the K-ion full battery delivers higher energy and power densities (172 Wh Kg-1 and 430 W Kg-1 ), comparable to those reported in state-of-the-art K-ion full batteries, accompanying with a capacity retention of ≈81.3% over 270 cycles. This result on Na-/K-ion batteries may pave the way to next-generation post-lithium batteries.

Potassium-ion batteries (KIBs) are regarded as a potential alternative battery technology to conventional lithium-ion batteries owing to their low potential, natural abundance, and the low cost of potassium. However, sluggish reaction kinetic of the much larger K+ ions leads to low rate capability and poor cycling performance of KIBs, restricting KIB’s practical applications. Herein, we propose a novel full battery called a potassium dual-ion hybrid battery (KDHB) by employing an absorption-type hierarchical porous carbon as the anode material and an anion intercalation-type expanded graphite (EG) as the cathode material. Owing to the hybrid mechanism of the battery and capacitive reaction, the KDHB exhibits superior rate performance with a high capacity of 82 mA h g–1 even at a high current density of 3 A g–1 with negligible capacity decay. Moreover, the KDHB exhibits excellent cycling performance with 74.2% capacity retention after 2000 cycles at 1 A g–1, which is so far the best performance of the repo...

With the development of flexible and wearable energy devices, it is highly desirable to exploit flexible and cost-effective electrode materials. In this work, we report a facile and in-situ method for preparing a three-dimensional (3D), flexible and binder-free anode material, composing of leaf-like MoS 2 nanostructures uniformly anchored on carbon nanofibers derived from carbonized bacterial cellulose (denoted as MoS 2 -cBC). With merits of high conductivity, good flexibility and high structural stability, the MoS 2 -cBC composite was directly used as the anode material and current collector for lithium ion batteries without any binder nor conductive additive. Moreover, owing to the synergistic effect of the uniformly deposited MoS 2 nanoleaves and the 3D highly conductive carbon nanofibers, the MoS 2 -cBC anode exhibits impressively superior electrochemical performance. A high reversible charge capacity of 935 mA h g −1 is achieved at 0.1 A g −1 , while a capacity of 581 mA h g −1 is maintained after 1000 cycles at 1 A g −1 with negligible decay, demonstrating much enhanced long-term cycling stability of the composite. The superior electrochemical performance together with the stability and cost-effective merits make the MoS 2 -cBC composite promising for next-generation energy storage devices.

The influence of the power terms Joule heating and radiative losses on the pinch radius in plasma focus devices is studied. Numerical experiments were carried out using the Lee model on three plasma focus devices spanning a large range of storage energy (PF400, INTI PF, PF1000) with different filling gases (N, O, Ne, Ar, Kr, Xe). Six possible regimes each characterized by a combination of significant power terms affecting plasma focus dynamics are found and discussed. These six possible regimes are further moderated by thermodynamic effects related to the specific heat ratio SHR of the plasma. In PF1000, the thermodynamic compression effects are clearly apparent in the radius ratio versus pressure curve for nitrogen which with atomic number Zn = 7 is less radiative than neon with Zn = 10, the dominant line radiation being proportional to Zn4. In neon radiative compression at optimum pressure is so dominant that it masks thermodynamic compression in the compression versus pressure graph. Results show that plasma radiation losses enhance the contraction of the plasma focus pinch radius within suitable pressure ranges characteristic of each machine for each gas discussed in this paper. The radiation enhancement of compression increases with the atomic number of the gas.

Experimental studies of discharges in the plasma focus facility with neon filling and respective numerical simulations employing the radiative Lee code are reported. The pinch currents exceed the Pease-Braginskii current, which indicates that radiative losses are larger than heating and that contraction of the formed plasma should occur. Both of these effects were indeed observed. Parallel numerical simulations were crucial for the identification of such an effect.

By rational design, rice-like sulfur/polyaniline nanorods wrapped with reduced graphene oxide nanosheets (designated rGO:S:PANI) were successfully synthesized through emulsification–polymerization followed by a hydrothermal process. In the rice-like S:PANI nanoparticles, the sulfur active material is uniformly distributed among the PANI polymer network. PANI not only provides a flexible matrix for accommodating volume changes in the active sulfur upon lithium insertion/extraction, the conducting polymer chains also provide high conductivity paths for effective charge transport. Benefiting from the electrostatic interaction between GO and PANI, the sulfur/polyaniline nanorods (designated S:PANI) can be well wrapped by the rGO nanosheets after the hydrothermal process, which can further increase the conductivity of the composite and prevent the polysulfide from dissolving upon cycling. When evaluated as a cathode for lithium–sulfur batteries, the rGO:S:PANI material exhibits a high specific capacity of 1240 mAh g−1 at a current density of 0.1 Ag−1, and a capacity of approximately 500 mAh g−1 (ca. 77 % retention) even at a high current rate of 1.5 Ag−1.

Interface engineering on 2D layered nanomaterials plays pivotal roles in achieving novel properties and superior device performance. In this work, hierarchical nanotubes consisting of 2D monolayer MoS2 and carbon (MoS2:C) interoverlapped superstructure nanosheets have been synthesized, in which the MoS2 and carbon layers are alternately sandwiched. The hierarchical architectures assembled from the MoS2:C superstructures are beneficial for: (i) providing substantially expanded (002) interlayer spacing (0.98 nm) of 2H-MoS2 which facilitates fast Na+ insertion/extraction reaction kinetics, (ii) improving electrical conductivity of MoS2 by carbon monolayer insertion with ideal heterointerface contact, (iii) preventing aggregation of MoS2 nanosheets, and (iv) accommodating volume change upon sodiation/desodiation. The superstructure nanotubes are demonstrated as a robust anode material for sodium storage with superior electrochemical performance. They deliver a high rate-capability and maintain discharge capacities of 295 and 187 mAh g−1 at high current densities of 10.0 and 20.0 A g−1, respectively. Furthermore, they show durable cycling life (capacity retention of 101.3%, 108.2% and 107.8% after 200 cycles at current densities of 0.2, 0.5 and 1.0 A g−1, respectively, in comparison to those of the 2nd cycles), and an initial Coulombic efficiency as high as 84%. The MoS2:C superstructure nanotubes perform among the best of current MoS2-based electrode materials.

The color rendering index (CRI) of a white organic-light emitting device (WOLED) employing standard red + green + blue emitters is typically limited by the deep valley between the red and the green emission peaks. To address this issue without increasing device complexity, we synthesized a yellowish-green iridium emitter, iridium(III) bis(2-phenylpyridine)(2-(benzo[d]oxazol-2-yl)phenol) (Ir(ppy)2bop), for replacing the standard green emitter. By combining emissions from Ir(ppy)2bop with those from a blue fluorescent emitter and a red phosphor, a high performance fluorescent/phosphorescent (F/P) WOLED has been fabricated. The device gives white emission with a maximum efficiency of 55.2 cd A−1 (49.6 lm W−1) and an EQE value of 20% without any light extraction technologies. It is noteworthy that the color rendering index (CRI) of the white OLED reaches up to 89. Considering both the efficiency and the CRI, these results are among the best-reported white OLEDs.

Interconnected porous FeS/C composite consisting of FeS nanoparticles (∼20 nm) homogeneously embedded in carbon nanosheets was synthesized via a facile freeze-drying/carbonization method using a NaCl template. As an anode for LIBs, this composite shows significantly enhanced electrochemical performance due to the synergistic effects of the conductive carbon film and the porous structure, which provides an ideal conductive matrix and buffer spaces for electron/ion transfer and FeS expansion, respectively, during lithiation processes. This composite exhibits reversible capacities of ∼703 mA h g−1 over 150 cycles at 1 A g−1 and a high-rate capability of ∼530 mA h g−1 even at 5 A g−1, which is among the best reported electrochemical performances for FeS-based materials thus far. With a long cycling life and high power density, this composite demonstrates its potential application in LIBs.

A water-soluble and emissive Eu-complex (EuL1) bearing a DO3A(Eu3+)–pyridine–aza-crown motif has been prepared and its Cu2+ complex has been demonstrated to be a smart luminescence “off–on” gate for H2S detection in water with a nano-molar detection limit (60 nM). EuL1 binds to Cu2+ ions selectively (KB = 1.2 × 105 M−1) inducing 17-fold luminescence quenching and forming a 1 : 1 stoichiometric complex (EuL1–Cu2+), which responds to H2S selectively with restoration of the original Eu emission of EuL1 followed by a further 40-fold luminescence enhancement, forming a 1 : 1 stoichiometric complex (EuL1–Na2S, KB = 1.5 × 104 M−1). Without Cu2+ ions, EuL1 showed non-specific binding towards H2S with only a 5-fold luminescence enhancement.