In situ Cu doping of ultralarge CoSe nanosheets with accelerated electronic migration for superior sodium-ion storage.

The progress of sodium-ion batteries is currently confronted with a noteworthy obstacle, specifically the paucity of electrode materials that can store large quantities of Na+ in a reversible fashion while maintaining competitiveness. Herein, ultrafast and long-life sodium storage of metal selenides is rationally demonstrated by employing micron-sized nanosheets (Cu-CoSe@NC) through electron accumulation engineering. The nanosheet structure proves to be effective in reducing the transport distance of sodium ions. Furthermore, the addition of Cu ions enhances the electron conductivity of CoSe and accelerates charge delocalization. As an anode for sodium-ion batteries, Cu-CoSe@NC exhibits a noticeably enhanced specific capacity of 527.2 mA h g-1 at 1.0 A g-1 after 100 cycles. Additionally, Cu-CoSe@NC maintains a capacity of 428.5 mA h g-1 at 5.0 A g-1 after 800 cycles. It is possible to create sodium-ion full batteries with a high energy density of 101.1 W h kg-1. The superior sodium storage performance of Cu-CoSe@NC is attributed to the high pseudo-capacitance and diffusion control mechanisms, as evidenced by theoretical calculations and ex situ measurements.

Interfacial covalent bonding of the MXene-stabilized Sb2Se3 nanotube hybrid with fast ion transport for enhanced sodium-ion half/full batteries.

An interfacial covalent bonding strategy is proposed for the synthesis of the MXene-stabilized Sb2Se3 nanotube hybrid. As an anode material, the prepared Sb2Se3@NC/MXene exhibits an enhanced sodium-ion battery performance in half/full batteries in terms of a high specific and cycling stability.

Flexible composite film with artificial opal photonic crystals for efficient all-day passive radiative cooling.

All-day passive radiative cooling has recently attracted broader attention for its potential as a viable energy technology. Although tremendous progress has been achieved, the design and fabrication of low-cost high-efficiency radiators for all-day passive radiative cooling remains a challenge. Herein, we report a new type of flexible composite radiator film with built-in artificial opal-like structures for all-day passive radiative cooling. Using artificial opal structure concepts, the proposed polydimethylsiloxane (PDMS) radiator film with embedded polystyrene (PS) microsphere photonic crystals exhibits a sufficiently high solar reflectance of ∼92.7% when in a direct sunlight region, and a thermal emittance of ∼93.6% within the atmospheric window. Without the need for traditional reflectors like silver or aluminum foils, this composite film realizes subambient temperature reduction of ∼4.8 °C in direct sunlight and ∼8.5 °C during the night. This work provides a new fabrication approach for the low-cost production of structural polymer films for high performance and potential real word applications.

Tuning the electronic structure of layered vanadium pentoxide by pre-intercalation of potassium ions for superior room/low-temperature aqueous zinc-ion batteries.

Aqueous zinc-ion batteries (ZIBs), due to their sluggish Zn2+ diffusion kinetics, continue to face challenges in terms of achieving superior high rate, long-term cycling and low-temperature properties. Herein, K+ pre-intercalated layered V2O5 (K0.5V2O5) composites with metallic features are capable of delivering excellent zinc storage performance. Specifically, the K0.5V2O5 electrode delivers a high reversible capacity of 251 mA h g-1 at 5 A g-1 after 1000 cycles. Even at a low temperature of -20 °C, high reversible capacities of 241 and 115 mA h g-1 can be obtained after 1000 cycles at 1 and 5 A g-1, respectively. The outstanding electrochemical performance is attributed to the incorporation of K+ into the layered V2O5, which acts as pillars to promote the Zn2+ diffusion and increase the structural stability during cycling. Density functional theory calculations demonstrate that the interlayer doping of K+ can benefit electron migration, and therefore enhance the Zn2+ (de)intercalation kinetics. Meanwhile, the Zn2+ storage mechanism of K0.5V2O5 is revealed by ex situ X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy characterization. This work may pave the way for exploiting high-performance cathodes for aqueous ZIBs.

Highly linearly polarized light emission from flexible organic light-emitting devices capitalized on integrated ultrathin metal-dielectric nanograting.

Although there have been tremendous achievements ever since the first work on an organic electroluminescent (EL) device that emitted polarized light, the development of flexible polarized emission organic light-emitting devices (OLEDs) is not without hurdles, and the challenge towards real-world applications still requires tremendous effort. In this paper, we proposed highly linearly polarized light-emission from flexible green OLEDs capitalized on integrated ultrathin metal-dielectric nanograting. The acquired polarized device with meticulously optimized geometric parameters yields an angle-invariant average extinction ratio beyond 20.0 dB within a viewing angle range of ± 60°. The detailed analysis illustrates that surface plasmons and cavity modes are simultaneously contributed to the TM-polarized light selection. We hope that the presented approach will open new opportunities for designing flexible polarized light sources.

Ruthenium trichloride catalyzed conversion of cellulose into 5-hydroxymethylfurfural in biphasic system.

The production of 5-hydroxymethylfurfural (5-HMF) from cellulose catalyzed by a series of transition metal chlorides (i.e. FeCl3, RuCl3, VCl3, TiCl3, MoCl3 and CrCl3) was studied in biphasic system. RuCl3 was the most efficient catalyst among these transition metal chlorides for 5-HMF production, and resulted in both the highest yield of 83.3% and selectivity of 87.5% in NaCl-aqueous/butanol biphasic system. XRD analysis and FTIR spectroscopy were applied to further characterize the RuCl3 catalyzed cellulose slurries to reveal the catalytic reaction mechanism. Results demonstrated that RuCl3 enhanced the decrystallization and cleavage of COC bonds in cellulose, promoted the subsequent dehydration of glucose into 5-HMF, while suppressed the glucose retro-aldol reaction to byproduct lactic acid. In addition, with the assistance of NaCl-aqueous/butanol biphasic system, 5-HMF further degradation was limited and thusly maintained a desired 5-HMF yield. This proposed approach provides an efficient strategy for one-pot conversion of cellulose into 5-HMF.

Platinum(II) Complexes with 1,10-Phenanthroline and Hydrophilic Alkoxyacetate Ligands as Potential Antitumor Agents.

Four platinum complexes, formulated as [Pt(phen)(OCOCH2 OR)2 ] (phen=1,10-phenanthroline, R=Me, Et, i Pr, or t Bu), have been synthesized and well characterized by elemental analysis, IR, 1 H-NMR, 13 C-NMR and ESI-MS spectroscopy. Replacing chloride groups of the precursor Pt(phen)Cl2 with alkoxyacetate anions greatly improved the aqueous solubility and cytotoxicity of the resulting platinum complexes. The in vitro cytotoxicity study revealed that complexes 1-3 were active in vitro towards four human tumor cell lines, especially complex 1 which exhibited prominent in vitro cytotoxic activity against HCT-116 cell lines comparable to cisplatin and oxaliplatin. Flow cytometry assay indicated that representative complexes 1 and 2 exerted cytotoxicity on HCT-116 cell lines through inducing cell apoptosis and blocking cell cycle progression in the S or G2/M phases. The interaction of representative complexes with pET28a plasmid DNA was tested by agarose gel electrophoresis, which demonstrated that complexes 1 and 2 were capable of distorting plasmid DNA mainly by covalent binding and degradation effect.

Laser speckle formed disordered micro-meander structures for light extraction enhancement of flexible organic light-emitting diodes.

A new approach for efficiently recovering the wasted light energy in conventional flexible organic light-emitting diodes (FOLEDs) is developed by implementing disordered micro-meander structures (DMMs) via laser speckle holography technology. Compared to conventional flat device architecture, the structured FOLEDs with DMMs result in substantial improvement of the device efficiency and superior angular color stability. The resulting current efficiency (CE) and external quantum efficiency (EQE) are 1.31 and 1.39 times that of a common flat structure, respectively. Moreover, the proposed DMMs micro-structure simultaneously offers the unique characteristics of angular color stability with a wide viewing angle, which is usually considered as the criteria of the high-quality lighting applications. We hope that the demonstrated method could provide an alternative way for the development of high efficiency flexible OLEDs.

Two novel blue phosphorescent host materials containing phenothiazine-5,5-dioxide structure derivatives.

Two novel D-A bipolar blue phosphorescent host materials based on phenothiazine-5,5-dioxide: 3-(9H-carbazol-9-yl)-10-ethyl-10H-phenothiazine-5,5-dioxide (CEPDO) and 10-butyl-3-(9H-carbazol-9-yl)-10H-phenothiazine-5,5-dioxide (CBPDO) were synthesized and characterized. The photophysical, electrochemical and thermal properties were systematically investigated. CEPDO and CBPDO not only have a high triplet energy but also show a bipolar behavior. Moreover, their fluorescence emission peaks are in the blue fluorescence region at 408 nm and the fluorescence quantum efficiency (Φ) of CEPDO and CBPDO were 62.5% and 59.7%, respectively. Both CEPDO and CBPDO showed very high thermal stability with decomposition temperatures (Td) of 409 and 396 °C as well as suitable HOMO and LUMO energy levels. This preferable performance suggests that CEPDO and CBPDO are alternative bipolar host materials for the PhOLEDs.

Three-dimensional nitrogen and sulfur co-doped holey-reduced graphene oxide frameworks anchored with MoO2 nanodots for advanced rechargeable lithium-ion batteries.

In this manuscript, we synthesize a porous three-dimensional anode material consisting of molybdenum dioxide nanodots anchored on nitrogen (N)/sulfur (S) co-doped reduced graphene oxide (GO) (3D MoO2/NP-NSG) through hydrothermal, lyophilization and thermal treatment. First, the NP-NSG is formed via hydrothermal treatment using graphene oxide, hydrogen peroxide (H2O2), and thiourea as the co-dopant for N and S, followed by calcination of the N/S co-doped GO in the presence of ammonium molybdate tetrahydrate to obtain the 3D MoO2/NP-NSG product. This novel material exhibits a series of out-bound electrochemical performances, such as superior conductivity, high specific capacity, and excellent stability. As an anode for lithium-ion batteries (LIBs), the MoO2/NP-NSG electrode has a high initial specific capacity (1376 mAh g-1), good cycling performance (1250 mAh g-1 after 100 cycles at a current density of 0.2 A g-1), and outstanding Coulombic efficiency (99% after 450 cycles at a current density of 1 A g-1). Remarkably, the MoO2/NP-NSG battery exhibits exceedingly good rate capacities of 1021, 965, 891, 760, 649, 500 and 425 mAh g-1 at different current densities of 200, 500, 1000, 2000, 3000, 4000 and 5000 mA g-1, respectively. The superb electrochemical performance is owed to the high porosity of the 3D architecture, the synergistic effect contribution from N and S co-doped in the reduced graphene oxide (rGO), and the uniform distribution of MoO2 nanodots on the rGO surface.

Rational synthesis of graphene-encapsulated uniform MnMoO4 hollow spheres as long-life and high-rate anodes for lithium-ion batteries.

In this manuscript, the graphene-encapsulated MnMoO4 hollow spheres (MnMoO4@G) synthesized by an effective strategy were reported. Benefiting from the intriguing hybrid architecture of hollow structure and conductive graphene network, the MnMoO4@G composite displays superior electrochemical performance with high specific capacity of 1142 mA h g-1, high reversible cycling stability of 921 mA h g-1 at a current density of 100 mA g-1 after 70 cycles, and stable rate performance (around 513 mA h g-1 at a current density of 4.0 A g-1). The remarkable battery performance can be attributed to the rational design of the architecture, which not only ensures the fast transport of electrons and lithium ions within the electrode material, but also effectively relax the stress induced by the insertion/extraction of lithium ions. This facile synthetic method can extend to other transition metal oxides with large volume excursions and poor electric conductivity and promotes the development of transition metal oxides as high-performance LIB anode material.

Charge transport dependent high open circuit voltage tandem organic photovoltaic cells with low temperature deposited HATCN-based charge recombination layers.

Mechanisms of charge transport between the interconnector and its neighboring layers in tandem organic photovoltaic cells have been systematically investigated by studying electronic properties of the involving interfaces with photoelectron spectroscopies and performance of the corresponding devices. The results show that charge recombination occurs at HATCN and its neighboring hole transport layers which can be deposited at low temperature. The hole transport layer plays an equal role to the interconnector itself. These insights provide guidance for the identification of new materials and the device architecture for high performance devices.

Controlling charge injection properties in polymer field-effect transistors by incorporation of solution processed molybdenum trioxide.

A simply and facilely synthesized MoO3 solution was developed to fabricate charge injection layers for improving the charge-injection properties in p-type organic field-effect transistors (OFETs). By dissolving MoO3 powder in ammonium (NH3) solvent under an air atmosphere, an intermediate ammonium molybdate ((NH4)2MoO4) precursor is made stable, transparent and spin-coated to form the MoO3 interfacial layers, the thickness and morphology of which can be well-controlled. When the MoO3 layer was applied to OFETs with a cost-effective molybdenum (Mo) electrode, the field-effect mobility (µFET) was significantly improved to 0.17 or 1.85 cm(2) V(-1)s(-1) for polymer semiconductors, regioregular poly(3-hexylthiophene) (P3HT) or 3,6-bis-(5bromo-thiophen-2-yl)-N,N'-bis(2-octyl-1-dodecyl)-1,4-dioxo-pyrrolo[3,4-c]pyrrole (DPPT-TT), respectively. Device analysis indicates that the MoO3-deposited Mo contact exhibits a contact resistance RC of 1.2 MΩ cm comparable to that in a device with the noble Au electrode. Kelvin-probe measurements show that the work function of the Mo electrode did not exhibit a dependence on the thickness of MoO3 film. Instead, ultraviolet photoemission spectroscopy results show that a doping effect is probably induced by casting the MoO3 layer on the P3HT semiconductor, which leads to the improved hole injection.

A recyclable carbon nanoparticle-based fluorescent probe for highly selective and sensitive detection of mercapto biomolecules.

Carbon nanoparticles (CNPs) with strong blue emission are synthesized using a microwave-assisted hydrothermal method. The fluorescence of the CNPs can be completely quenched by Hg2+ through an effective electron or energy transfer process due to the synergetic strong electrostatic interaction and metal-ligand coordination. Based on this, a system containing Hg2+-quenched CNPs (CNP-Hg2+) is designed to be a sensitive and selective turn-on fluorescent probe towards cysteine (a type of mercapto biomolecule) with a detection limit of 15 nM. The fluorescence of CNP-Hg2+ aqueous solution can be repeatedly turned on and off for over 10 times by alternative addition of cysteine and Hg2+, respectively. After 10 cycles, the fluorescence intensity could be recovered to as high as 85% of the original value of CNPs. Remarkably, the sensing process is able to be observed by the naked eye under UV irradiation. Furthermore, the sensing is specific to biothiols and the sensor is able to work in living cells.

Surface engineering of reduced graphene oxide for controllable ambipolar flash memories.

Tunable charge-trapping behaviors including unipolar charge trapping of one type of charge carrier and ambipolar trapping of both electrons and holes in a complementary manner is highly desirable for low power consumption multibit flash memory design. Here, we adopt a strategy of tuning the Fermi level of reduced graphene oxide (rGO) through self-assembled monolayer (SAM) functionalization and form p-type and n-type doped rGO with a wide range of manipulation on work function. The functionalized rGO can act as charge-trapping layer in ambipolar flash memories, and a dramatic transition of charging behavior from unipolar trapping of electrons to ambipolar trapping and eventually to unipolar trapping of holes was achieved. Adjustable hole/electron injection barriers induce controllable Vth shift in the memory transistor after programming operation. Finally, we transfer the ambipolar memory on flexible substrates and study their charge-trapping properties at various bending cycles. The SAM-functionalized rGO can be a promising candidate for next-generation nonvolatile memories.

Facile approaching hierarchical CdS films as electrode toward photoelectrochemical water splitting.

The facile generation of hierarchical CdS films and their accompanying application comparison as efficient photocatalytic electrodes toward water splitting were successfully achieved in this study. Three hierarchical CdS films, including nanoparticle packing film (CdS(P)), neat film (CdS(N)) and homojunction film (CdS(H)) deposited on an indium tin oxide (ITO) substrate, were realized by virtue of chemical bath deposition (CBD), atomic layer deposition (ALD) and the well-programmed combinational deposition (PCD) protocol with the above two processes successively. The experimental details demonstrate that the CdS(H) film acquired from PCD affords an amazing photocatalytic boost toward water splitting, which may profit from the larger surface area and from better absorption. The adoption of CdS(H) film as a photocatalyst can result in up to 22.18 times or 3.34 times the enhancement of the photocurrent density compared to reference devices with a CdSP or CdSN photoelectrode, indicating the effectiveness of the excogitation of the programmed protocol. Ultraviolet photoelectron spectroscopy was utilized to elucidate the electronic structures of the CdS(H) bilayer photoanode, and the dependence of their directional photocurrent on the energy level alignment was also depicted. This work not only excogitates the programmed deposition protocol that may be facilely extended to the fabrication of other hierarchical nanomaterials but also gives prominence to the importance of morphology and interfacial energetic control toward enhancing catalytic efficiency.

Synthesis of honeycomb-like mesoporous pyrite FeS2 microspheres as efficient counter electrode in quantum dots sensitized solar cells.

Honeycomb-like mesoporous pyrite FeS2 microspheres, with diameters of 500-800 nm and pore sizes of 25-30 nm, are synthesized by a simple solvothermal approach. The mesoporous FeS2 microspheres are demonstrated to be an outstanding counter electrode (CE) material in quantum dot sensitized solar cells (QDSSCs) for electrocatalyzing polysulfide electrolyte regeneration. The cell using mesoporous FeS2 microspheres as CE shows 86.6% enhancement in power conversion efficiency (PCE) than the cell using traditional noble Pt CE. Furthermore, it also shows 11.4% enhancement in PCE than the cell using solid FeS2 microspheres as CE, due to the mesoporous structure facilitating better contact with polysulfide electrolyte and fast diffusion of redox couple species in electrolyte.

Highly efficient orange and warm white phosphorescent OLEDs based on a host material with a carbazole-fluorenyl hybrid.

A new carbazole-fluorenyl hybrid compound, 3,3'(2,7-di(naphthaline-2-yl)-9H-fluorene-9,9-diyl)bis(9-phenyl-9H-carbazole) (NFBC) was synthesized and characterized. The compound exhibits blue-violet emission both in solution and in film, with peaks centered at 404 and 420 nm. In addition to the application as a blue emitter, NFBC is demonstrated to be a good host for phosphorescent dopants. By doping Ir(2-phq)3 in NFBC, a highly efficient orange organic light-emitting diode (OLED) with a maximum efficiency of 32 cd A(-1) (26.5 Lm W(-1)) was obtained. Unlike most phosphorescent OLEDs, the device prepared in our study shows little efficiency roll-off at high brightness and maintains current efficiencies of 31.9 and 26.8 cd A(-1) at a luminance of 1000 and 10,000 cd m(-2), respectively. By using NFBC simultaneously as a blue fluorescence emitter and as a host for a phosphorescent dopant, a warm white OLED with a maximum efficiency of 22.9 Lm W(-1) (21.9 cd A(-1)) was also obtained.

Enhanced performance of polymer solar cell with ZnO nanoparticle electron transporting layer passivated by in situ cross-linked three-dimensional polymer network.

An in situ cross-linked three-dimensional polymer network has been developed to passivate ZnO nanoparticles as an electron transporting layer (ETL) to improve the performance of inverted organic solar cells. The passivated ZnO ETL-based devices achieve efficiencies of 3.26% for poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and 7.37% for poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) devices compared with 2.58% and 6.67% for the control devices respectively. The origin of the improvement is studied by investigating the influence of the transport barrier, morphology and recombination. Atomic force microscopy (AFM), photoluminescence (PL) and transient photocurrent (TPC) measurements prove the boosted performance originates from the improved film-forming quality as well as passivated defects in the ZnO film, decreasing the trap-assisted recombination rather than giving better energy alignment between the active layer and the ZnO interlayer.

High-efficiency hybrid solar cells based on polymer/PbSx Se1-x nanocrystals benefiting from vertical phase segregation.

Solution-processed hybrid solar cells employing a low band-gap polymer and PbSx Se1-x alloy nanocrystals, achieving a record high PCE of 5.50% and an optimal FF of 67% are presented. The remarkable device efficiency can be attributed to the high-performance active materials, the optimal polymer/NCs ratio and, more importantly, the vertical donor/(donor:acceptor)/acceptor structure which benefits charge dissociation and transport.