Search

Ni-doped WC/Mo 2 C composites for hydrogen evolution reaction (HER) were synthesized in situ grown on carbon fiber paper (CFP) by molten salt method in argon at 1000 °C for 6 h, named as Ni-xWC-y/2Mo 2 C@CFP. The effects of different W/Mo molar ratios (3:1, 2:1, 1:1, 1:2, 1:3) on the phase composition, microstructures, and HER performances were investigated. The results showed that the W/Mo molar ratio had a synergistic effect in HER of Ni-doped WC/Mo 2 C composites, and as W/Mo molar ratio at 1:1, the composite presented the best electrocatalytic activity. Meanwhile, its surface appeared to have a wrinkle-like structure, and the biphasic heterostructure emerged at the intersection of the dual-phase WC and Mo 2 C lattices. The introduction of a biphasic heterostructure could promote charge transfer and improve HER efficiency. Predictably, the electrocatalysts with the optimal W/Mo molar ratio 1:1 exhibited the best hydrogen evolution performance, needed only 43.7 mV overpotential to reach 10 mA cm−2 current density with a Tafel slope at 21.3 mV dec−1. In this work, the high-efficiency electrocatalysts of Ni-doped 1WC-1/2Mo 2 C@CFP have been prepared, which provides an insight into theoretical research of composite carbon-based electrocatalysts. [ABSTRACT FROM AUTHOR]

The diffusion layer (DL) in the structure of the membrane electrode assembly (MEA) of a micro direct methanol fuel cell (μDMFC) plays an essential role in reactant/product mass transfer and catalyst loading. The material selection and structure design of the μDMFC affects its performance. In this work, a reduced graphene oxide/carbon paper (rGO/CP) was proposed and prepared for the anode DL of a μDMFC. It was prepared using electrophoretic sedimentation combined with an in situ reduction method. The rGO/CP reduced the cell's ohmic and charge transfer resistances. Meanwhile, it provided more significant mass transfer resistance to reduce the methanol crossover, allowing the cell to operate stably at higher concentrations for a longer duration than conventional μDMFCs. The experimental results showed that the maximum power density increased by 53% compared with the traditional anode DL of carbon paper. [ABSTRACT FROM AUTHOR]

Summary: This work describes a two‐step method of in situ electrodeposition and following oxidation to prepare carbon paper (CP) modified with tin dioxide (SnO2) particle as bifunctional electrode for vanadium redox flow battery. Electrodeposition technique was employed to load metal tin particle on CP, which was subsequently oxidized to tin dioxide at high temperature. CPs modified by SnO2 with different content (CP/SnO2‐1, CP/SnO2‐2, and CP/SnO2‐3) were obtained by controlling electrodeposition time. CP/SnO2 presents an increase in electrochemical performance including faster charge and mass transfer compared with pristine CP. Among all samples, CP/SnO2‐2 with proper decorated SnO2 exhibits superior electrocatalytic performances for V3+/V2+ and VO2+/VO2+ reactions. Raised performances can be attributed to that SnO2 nanoparticles provide more active sites leading to rapid electrochemical kinetic of vanadium redox reactions. In addition, mass transfer can be accelerated due to the excellent hydrophilicity of SnO2. The cell using CP/SnO2‐2 as bifunctional electrode exhibits better stability and higher capacity retention during 50‐cycle charge‐discharge test. The cell for CP/SnO2‐2 shows higher energy and voltage efficiency, suggesting that introduction of SnO2 can decrease electrochemical polarization. At 150 mA cm−2, energy efficiency of the cell increases by 7.8% through using CP/SnO2‐2. [ABSTRACT FROM AUTHOR]

Simultaneous detection of multiple amino acids (AAs) instead of individual AAs is inherently worthwhile for improving diagnostic accuracy in clinical applications. Here, a facile and reliable colorimetric microfluidic paper-based analytical device (μPAD) using carbon dots doped with transition metals (Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, and Zn2+) has been provided to detect and discriminate 20 natural amino acids. To make the colourless metal-doped carbon dots suitable for colorimetric assays, they were mixed with ninhydrin to form a charge transfer complex. This optical tongue system, which was constructed by dropping mixtures of ninhydrin with a series of metal-doped carbon dots on a paper substrate in an array format, represented obvious but different colorimetric signatures for every examined amino acid. Since bovine serum albumin was used as a chiral selector reagent for synthesizing the CDs, the sensor device represented excellent selectivity to identify enantiomeric species of AAs. This is the first optical array device that can simultaneously discriminate AAs and several of their enantiomers. We employed various statistical and chemometric methods to analyze the digital data library collected by Image J software, including principal component analysis (PCA), linear discriminant analysis (LDA), and hierarchical cluster analysis (HCA). Twenty AAs could be well distinguished at various concentrations (10.00, 5.00, 2.50, and 1.25 mM). The colorimetric patterns were highly repeatable and were characteristic of individual AAs. Besides qualitative analysis, the designed μPAD-based optical tongue represented quantitative analysis ability, e.g., for lysine in the concentration ranges of 0.005–20.0 mM with a detection limit of 1.0 × 10−6 M and for arginine in the concentration range of 0.12–20.00 mM with a detection limit of 80.0 × 10−6 M. In addition, the binary, ternary, and quaternary mixtures of AAs could also be well recognized with this sensor. [ABSTRACT FROM AUTHOR]

• The carbon paper as the substrate was used to synthesize CEs in DSSC for the first time. • The CoP 3 /CP electrode exhibited low charge transfer resistance. • The DSSC with CoP 3 /CP electrode achieved the photoelectric conversion efficiency of 6.84%. The cobalt triphosphide (CoP 3) was grew on carbon paper (CP) by using a hydrothermal method and served as counter electrode (CE) catalyst in dye-sensitized solar cells (DSSCs). The morphology of the CoP 3 /CP CE exhibits a regular fibrous structure, which provides a guarantee for its good electrochemical performance of the CE made from the cyclic voltammetry, Tafel test, etc. Various photoelectric performance tests also show that the DSSCs with CoP 3 /CP CE achieves good photoelectric conversion efficiency of 6.84% under 100 mW·cm−2 illumination, which can compare to that of the DSSC assembled with the Pt (6.79%) CE. Metal phosphides are rarely used as CEs in DSSCs, and they will have a good promising alternative to the Pt electrode in the future. [ABSTRACT FROM AUTHOR]

Summary: Tremendous research has focused on the wearable electronic device, leading to the basic requirement of suitable power sources. Herein, we report one bendable paper‐based zinc‐air battery with a novel hollow channel structure. It achieves a maximum power density of 138 mW/cm2, outperforming the state‐of‐art paper‐based batteries reported previously. The boosted performance is assigned to the low charge transfer resistance and facilitated mass transfer from the hollow structure. It demonstrates the positive design of microchannel structure is profitable for the power‐generation enhancement, and offers a possible route to commercialize the paper‐based power generators. [ABSTRACT FROM AUTHOR]

• A simple and fast method for loading electrocatalyst Ni 2 B on carbon paper. • A simple process that provides ideas for industrial production. • The solution resistance (Rsol) is only 2.68 Ω after electrochemical impedance testing on Ni 2 B/cp. • The mass of catalyst loaded is only (2–2.5) mg per cm2. In this paper, nickel boride (Ni 2 B) was successfully loaded on carbon fiber paper by electrodeposition and high temperature annealing. The activities of the electrode materials were compared at different deposition currents. The results show that the Ni 2 B/CP-2 electrode with a high surface crystallinity and tetrahedral structure exhibits excellent (OER) activity. Specifically, it can drive a current density of 10 mA cm−2 at a low overpotential of 280.4 mV in 1 M KOH solution, and it has the highest TOF value among these four materials. Furthermore, highly electronegative boron reduces the energy barrier of the nickel metal oxidation reaction and contributes to the charge transfer. [ABSTRACT FROM AUTHOR]

We report on the fabrication of zinc oxide (ZnO) nanorod-based flexible, cost-effective single electrode triboelectric nanogenerator (STENG) on cellulose paper platform. In particular, the influence of surface functional groups of ZnO nanorods on the STENG output has been investigated. The STENG has been designed with chemically grown ZnO nanorod-coated paper as active triboelectric layer and Teflon/ Aluminum as counter triboelectric layer/ electrode. It has been found that post-annealing of nanorods at 125∘C improves the output voltage by twice compared to the pristine nanorods and delivers an output power of ∼ 0. 2 μ W/cm2. With annealing up to 125∘C, the optimal removal of the chemisorbed water from the defect sites of ZnO surface increases the intrinsic carrier concentration leading to maximum charge transfer and hence higher triboelectric output. On the other hand, a higher extent of oxygen accumulation from air at 150∘C lowers the intrinsic carrier concentration resulting in the reduced output. It has been proposed that the competition between the events like water removal and oxygen accumulation under different annealing temperatures can influence the STENG output largely. Finally, the optimized STENG has been demonstrated to work as wearable bio-mechanical sensors operating through bio-mechanical stimuli. [ABSTRACT FROM AUTHOR]

• Development of and γ-Fe 2 O 3 modified exfoliated graphite carbon paper (γ-Fe 2 O 3 @ExGCP) for non-enzymatic glucose sensor. • The sensitivity of γ-Fe 2 O 3 @ExGCP electrodes is ∼7.1 µA mM-1cm−2, two times more than ExGCP paper. • The enhanced sensitivity of γ-Fe 2 O 3 @ExGCP is attributed to valency change of iron. • The charge transfer resistance is decreasing with increased glucose concentration. We report the γ-Fe 2 O 3 modified exfoliated graphite (γ-Fe 2 O 3 @ExGCP) flexible paper electrode as a non-enzymatic glucose sensor. The γ-Fe 2 O 3 was physically mixed with exfoliated graphite flakes, and mechanically pressed to get a thin sheet. The amperommetric analysis of γ-Fe 2 O 3 @ExGCP electrode shows that the sensor current increases with increasing glucose concentration. The impedance analysis of γ-Fe 2 O 3 @ExGCP substantiates the reduction in charge transfer resistance with increasing glucose concentration. The observed values of sensitivity for Ex-GCP and γ-Fe 2 O 3 @ExGCP electrodes are 3.51 µA mM-1cm−2 and 7.1 µA mM-1cm−2, respectively. The calculated LOD is 512 μM for γ-Fe 2 O 3 @ExGCP. Thus, γ-Fe 2 O 3 @ExGCP flexible electrode may be used for non-enzymatic glucose sensor with enhanced sensitivity. [ABSTRACT FROM AUTHOR]

Designing efficient non-precious metal catalysts with superior activity and stability for water splitting has been the pursuit of researchers. The purpose of this work is to investigate the influence of 2-amino terephthalic acid on the surface engineering of flower-like Co-N-C for improved water splitting in an alkaline solution. The flower-like Co-N-C grown on carbon paper (Co-N-C/CP) were fabricated by a facile hydrothermal and subsequent annealing process. When the ratio of Co2+ and 2-amino terephthalic acid reaches 1:2 in the precursors, the resultant Co-N-C/CP exhibits the overpotential of 181 mV and 290 mV at 10 mV cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Furthermore, the Co-N-C/CP (1:2)||Co-N-C/CP(1:2) water splitting systems deliver a current density of 10 mA cm−2 at 1.56 V. After 1500 cycles, the required voltage for water splitting still maintains at 1.57 V. The outstanding electrocatalytic properties are attributed to the tuning electron structure on the surface of Co-N-C, which promotes the charge transfer and chemical mass transport during water splitting in an alkaline solution. This study provides a new opportunity to develop highly efficient cobalt-based catalysts for enhanced water splitting. [Display omitted] • 2-amino terephthalic acid (2-NH 2 -BDC) was used to assist in the synthesis of flower-like Co-N-C for overall water splitting. • The surface electronic structure and morphology of flower-like Co-N-C can be modulated by adjusting the Co/N ratio. • The Co-N-C/CP (1:2) exhibits excellent activity and stability for HER and OER in an alkaline solution. • Co-N-C/CP(1:2)║Co-N-C/CP(1:2) shows the superior catalytic ability for overall water splitting. [ABSTRACT FROM AUTHOR]

This study proposes a low-cost, portable paper-fluidic vertical flow assay bacterium counter with high accuracy. We designed sensors with low fabrication costs based on e-beam evaporation and three-dimensional printing based on the impedance measurement principle. Interdigitated (IDT) electrodes were coated on the filter membrane by e-beam evaporation with a shadow mask. We could print wafer-scale frames with low melting temperature three-dimensional-printing materials for confining liquid bacterial samples within the IDT sensing region. This novel fabrication technique significantly reduced the chip's cost to less than 1% of that of silicon-based chips. Two equivalent circuit models were proposed for different concentration ranges to analyze the principle of paper-based impedance bacterial sensors. We proposed an improved model based on the Randles model for low concentrations by considering the leaky double-layer capacitor effect and spherical diffusion from the nano-structural electrodes of the gold-coated filter membrane. The phenomenon in which charge transfer resistance, Rct, declines at high concentration ranges was found and explained by the pearl chain effect. The pearl effect could cause a false-negative at high concentrations. We modeled the pearl chain effect as an R and C, connected parallel to the low-concentration model. When users properly applied both models for analyses, this sensor could quantitatively measure cell concentrations from 400 to 400 M per milliliter with superior linearity. [ABSTRACT FROM AUTHOR]

Herein, we develop a facile and efficient Thermal-Vaporization-Transformation (TVT) approach to prepare a highly active BP directly grown on carbon paper as the electrode for Oxygen evolution reaction (OER), showing a low onset potential of 1.45 V versus RHE. Simultaneously, the current density of BP-CP illustrates the excellent electro-catalysis stability only decreases by 3.4% after continuous operation for 10,000 s. [Display omitted] • BP-CP for OER is successfully synthesized by a novel efficient TVT approach. • The raw materials of the reaction are only the red phosphorus and carbon. • BP-CP exhibits a low onset potential and excellent electro-catalysis stability. • Electrocatalytic performance is fully demonstrated by DFT calculation in details. Black phosphorus (BP), as a new 2D material, is normally synthesized by a high-pressure and high-temperature (HPHT) method from white and red phosphorus, which severely hinders the further development of BP for any potential applications and leads to search for other potential applications of BP with big challenge. Herein, we develop a facile and efficient Thermal-Vaporization-Transformation (TVT) approach to prepare a highly active BP directly grown on carbon paper as the electrode for Oxygen evolution reaction (OER), showing a low onset potential of 1.45 V versus RHE. Simultaneously, the current density of BP-CP illustrates the excellent electro-catalysis stability only decreases by 3.4% after continuous operation for 10000 s. Meanwhile, the density functional theory (DFT) calculations further illustrates the P-doped carbon layer in the upper side of BP layer is actually responsible for its enhanced OER property, and the adjacent carbon atoms of the embedded P atoms are actually the active sites due to the induced local change distribution by intramolecular change transfer. Considering the facile, but efficient and scalable, TVT approach can directly synthesize BP-CP with excellent OER performance, which is promising for BP electrocatalysts used for OER in metal-air batteries, fuel cells, water-splitting devices, even other key renewable energy. [ABSTRACT FROM AUTHOR]

Transition metal oxides (TMOs) have great potential application in oxygen evolution reaction (OER). However, the inferior electrical conductivity and limited active sites of TMOs lead to their sluggish electrocatalytic efficiency. Herein, we adopted a two-step solvothermal approach to fabricate hierarchical CoO@NiO porous core–shell nanoarrays on carbon paper (denoted as CoO@NiO/CP). We found that numerous NiO nanofibers were uniformly coated over the surface of CoO nanosheets, forming a well-defined integrated interfacial nanocomposite. When acting as a catalyst for the OER, CoO@NiO/CP showed enhanced electroactivity with lower overpotential (323 mV at 10 mA cm−2), outstripping both pure CoO nanosheet array and NiO nanofiber array. Furthermore, it displayed outstanding OER stability, and the potential attenuation was only 3.4% after a 24 h chronopotentiometry test. The remarkable OER properties of CoO@NiO/CP were mainly due to its unique heterointerface between CoO and NiO, which promoted electron/charge transfer, increased electrocatalytic reactive sites, and improved electrical conductivity. Our presented findings provide a rational and practical interface-engineering approach for fabricating an advanced OER electrocatalyst. [ABSTRACT FROM AUTHOR]

This work reports a microfluidic paper-based photoelectrochemical (μ -PEC) sensing platform for thrombin (TB) detection with electron-transfer tunneling distance regulation (ETTDR) and aptamer target-triggering nicking enzyme signaling amplification (NESA) dual strategies. Specifically, paper-based TiO 2 nanosheets (PTNs) were prepared with an efficient hydrothermal process, serving as the direct pathway for the charge carriers transfer. When CeO 2 -labeled hairpin DNA 3 (HP3) was closely located at the PTNs, the CeO 2 -PTNs heterostructure was formed, which could great facilitate the photogenerated carries separation of CeO 2. In addition, with the aid of aptamer target-triggering NESA strategy, the input TB could be transducted to numerous output target of DNA (tDNA), achieving the goal of desirable signal amplification. In the presence of TB, the output tDNA could be further hybridized with HP3 and unfold its hairpin loop, which forced the CeO 2 away from the surface of PTNs and vanished the CeO 2 -PTNs heterostructure, resulting in the obviously reducing of photocurrent signal. The as-designed sensing platform exhibited a linear range from 0.02 pM to 100 pM with a detection limit of 6.7 fM. Importantly, this μ -PEC sensing platform could not only realize the highly efficient TB detection, but also pave a luciferous way for the detection of other protein in bioanalysis. • Paper based TiO 2 nanosheets are prepared with a hydrothermal strategy. • Aptamer target-triggering nicking enzyme signaling amplification (NESA) strategy is proposed. • Electron-transfer tunneling distance regulation (ETTDR) strategy is proposed. • A microfluidic paper based photoelectrochemical sensing platform is constructed. [ABSTRACT FROM AUTHOR]

In this paper, the temporal space charge dynamics under both temperature and voltage polarity reversal of an epoxy resin impregnated crepe paper are characterized by pulsed electroacoustic method. It is found that the space charge injection and the interfacial traps located between the epoxy and paper plays an important role in determining the space charge dynamics. The results reveal that below 353 K, the calculated interfacial charge density is consistent with the Maxwell-Wagner (MW) model, while above 353 K, it is smaller than the measured value. The time constant during charging is much smaller than that predicted by the MW model and the space charge injection showed polarity effect, which leads to the interfacial charge densities under polarity poling voltage not being equal. It is proposed that the interfacial traps and space charge injection should be responsible for the observed space charge dynamics. [ABSTRACT FROM AUTHOR]

Metallo‐supramolecular polymers (MSPs) show reversible electrochromic (EC) properties by electrochemical redox of metal ions included in the polymers. This presentation introduces recent three research achievements on EC devices (ECDs) using MSPs: (1) fabrication of highly durable ECDs with cycle stability more than 100,000 times, (2) a new electro‐polymerization method of a thin MSP layer on an ITO‐coated glass or PET‐film, and (3) rewritable multicolor EC paper using MSPs. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescent (TADF) and phosphorescent blue organic light‐emitting diodes (OLEDs) have been developed to overcome the relatively low triplet exciton utilization of traditional fluorescent OLEDs. However, broad emission spectra originating from charge transfer process limits the commercial application of such blue OLEDs. Herein, an effective phosphor‐sensitized fluorescent (PSF) OLED device structure was designed. PSF OLED exhibited a maximum blue index (BI) of 508 cd/A/CIEy with CIEy of 0.060, which has been the highest efficiency result reported for PSF deep‐blue OLEDs. Impressively, the sensitized OLEDs maintained blue index of 407 cd/A/CIEy, narrow emission spectra (FWHM = 17 nm) and high color purity (CIEy = 0.046), revealing the attractive technical advantages and commercial application potential. [ABSTRACT FROM AUTHOR]

Narrowband organic emitters are promising for their potential applications in wide‐color gamut and high‐resolution displays. Multiple resonance (MR) thermally activated delayed fluorescence (TADF) emitters are flourishing because of their attractive narrow emission bandwidth and excellent device performance. In this work, a series of MR‐TADF emitters embedded with sulfur, sulfone, and carbonyl have been developed, and their intrinsic effects on the exciton dynamics like intersystem crossing rate (kISC) and reverse intersystem crossing rate (kRISC) and full width at half maximum are systematically investigated. Benefitting from the heavy atom effect of the sulfur atom, fast kRISC are achieved to give highly efficient and stable organic light‐emitting diodes with reduced efficiency roll‐off. By fusing donor unit containing carbonyl into boron‐nitrogen compounds, carbonyl reinforced short range charge transfer can induce a red‐shifted pure‐green emission with simultaneous fast kRISC and narrow emission bandwidth, and a moderate device lifetime of LT90 (the time to 90% of the initial luminance of 1000 cd m‐2) of 127.3 h is achieved for the device utilizing TCZBAO as emitter. [ABSTRACT FROM AUTHOR]

This paper reports on a new method to measure the mobilities of both positive and negative charges in insulating materials based on space charge measurement in two-layer samples. To fulfill the condition of a unipolar carrier system, a blocking material is used as a barrier on one electrode thereby preventing charge injection to ensure the unipolar charges injected from the other electrode are transported through the bulk and accumulate at the barrier. Experimentally, the carrier mobility of oil immersed cellulose paper was obtained using the proposed method, and the result of mobilities of both positive and negative charges is presented. The temperature and field dependence of carrier mobility were also investigated, and the activation energies for negative and positive charges were calculated. The obtained carrier mobility of negative charges (majority electron carriers) is approximately 2 times of that of positive charges, and the charge migration can be interpreted by the thermally activated hopping conduction mechanism. [ABSTRACT FROM AUTHOR]

In this work, we report an unexplored heterostructured catalyst consisting of Ni–Co-phosphate/sulphide phases (NCPSP) on carbon fibre paper through a single-step gas–solid reaction route for hydrogen evolution reaction (HER) in an acidic medium. The heterostructured electrode film of NCPSP depicted considerably enhanced electrochemical HER performance compared to the heterostructured controlled catalyst films consisting of Ni–Co-phosphide phases (NCPP), Ni–Co-sulphide phases (NCSP), and Ni–Co-phosphate/phosphide phases (NCPPP). Electrochemical and structural characterization reveals that superior catalytic credentials of NCPSP can be attributed to kinetically favourable H binding on the sulphur sites of transition metal (TM) sulphides and their beneficial heterostructure with TM phosphate component. Specifically, the minimum overpotential of 53 mV and 97 mV is observed for cathodic HER current of 10 mA cm−2 and 100 mA cm−2, respectively. The low Tafel slope of 43 mV dec−1 reveals the favourable Volmer–Heyrovsky mechanism. Also, superior kinetics was revealed by the low charge transfer resistance of 28 Ω. The catalytic credentials of NCPSP are also well in alignment with the highest values reported for the best state of art catalysts. [ABSTRACT FROM AUTHOR]

• In-situ growth of MoS 2 over MnCO 3 inhibits formation of Mn-oxides/hydroxide. • MnCO 3 transforms to Mn(OH) 2 in aqueous KOH and stores charge by redox processes. • Mn(OH) 2 and MoS 2 afford low diffusion and charge transfer resistances, respectively. • MnCO 3 @MoS 2 hybrid utilized as negative electrode in asymmetric supercapacitor. This article puts forward a novel approach of combining the battery-type charge storage material, Mn(OH) 2 , indirectly with the two-dimensional material, MoS 2 , to develop the composite MnCO 3 @MoS 2 (designated as MCMS). A single-step facile hydrothermal method is described here for the synthesis of MCMS on a low-cost graphite substrate. Furthermore, this as-synthesized binder-free electrode is utilized as the negative electrode of an all-solid state asymmetric alkaline supercapacitor, employing NiCo 2 O 4 as the high specific energy positive electrode material. The overall asymmetric cell is shown to achieve a high specific energy of 48.97 W.h.kg −1 at 600 W.kg −1 and a high specific power of 12 kW.kg −1 at 11.33 W.h.kg −1, within a potential window of 1.2 V. Also, the composite electrode notably retains 86.5% of its gravimetric discharge capacity after 10,000 cycles with complete retention of its coulombic efficiency. The present work contributes to the development of a facile strategy for the preparation of non-carbonaceous hybrid materials suitable for high specific energy negative electrodes. [ABSTRACT FROM AUTHOR]

In this study, we reported the photoluminescence (PL) behaviour of a new intramolecular charge transfer (ICT) compound, ((E)-2-(((2-hydroxynaphthalen-1-yl)methylene)amino)benzoic acid, (HABA), which shows ICT solvent effect in aprotic solvents as confirmed by absorption and emission spectra. While in protic solvents including water and ethanol, the charge transfer (CT) band significantly reduces. Remarkable fluorescence enhancement in the blue region was also observed for HABA in polar protic solvents. We described such phenomena as “specific solvent effect”. It can be ascribed to the hydrogen bonding formation between HABA and protic solvents, which not only causes significant reduction in the rate of internal conversion but also elevates the energy gap. Density functional theory (DFT) calculations as well as the dynamics analysis were performed to further verify the existence of hydrogen bonding complexes. Stronger emission turn-on effect was observed on HABA solid film when it is treated with water and base solution. The stimuli-responsive fluorescence of HABA enables a new green printing technique that uses water/base as the ink, affording fluorescent handwritings highly distinct from the background. Thermoanalysis of the dye suggests the nice thermostability, which is highly desired for real-world printing in a wide temperature range. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new Schiff base based compound 2 with AIEE and reversible piezofluorochromic properties was synthesized. • Compound 2 was used for the sensitive colorimetric and ratiometric fluorescent (LOD; 2.13 nM) detection of Cu2+ based on 2 –Cu2+ complex that was accomplished through intermolecular charge transfer (ICT). • Probe 2 –Cu2+ was further applied for the nanoscale (LOD; 2.02 nM) detection of glutathione (GSH) due to the preferential affinity of Cu2+ for GSH. • Successful use of paper sensor for the detection of Cu2+ and GSH in food validates the authenticity of the developed strategy. A new Schiff base 2 was rationally synthesized that exhibited aggregation induced emission enhancement (AIEE) and unique reversible piezofluorochromic properties. Probe 2 displayed a distinguished ratiometric fluorescent and colorimetric recognition of Cu2+ and further acted as a probe for the selective detection of glutathione (GSH) based on its 2 –Cu2+ complex. Firstly, probe 2 showed a highly selective fluorescence quenching response towards Cu2+ over its competing ions that was attributed to the intermolecular charge transfer (ICT) to paramagnetic Cu2+. Based on ratiometric fluorescence titration, the limit of detection (LOD) of probe 2 for Cu2+ was calculated as 2.13 nM. The complexation mode of probe 2 for Cu2+ was confirmed through 1H NMR titration, Job plot, computational, and DLS studies. Subsequently, the addition of GSH to probe 2 –Cu2+ complex immediately enhanced its fluorescence, and the emission of probe 2 was recovered which was ascribed to the displacement of Cu2+ by GSH and release of probe 2. The developed strategy for the identification of GSH was confirmed through 1H NMR titration experiments. Advantageously, probe 2 and probe 2 –Cu2+ complex coated paper sensors were successfully developed for the nanoscale sensing of Cu2+ and GSH in food samples. The detection of Cu2+ and GSH in food and actual water samples was adequately accomplished through a very effective dip-coating method. Finally, a sequential detection strategy was used to design logic circuits. [ABSTRACT FROM AUTHOR]

This paper proposed a simulation method for the charge transport in single-layer oil-paper insulation. The method of transient upstream finite-element method (FEM) is derived in order to calculate the time variation of charge densities in medium. The numerical simulation of charge transport in the single-layer oil-paper insulation is realized by applying the transient upstream FEM to the transport equations of bipolar charges. With reasonable microparameter, the charge transport in an experimental object is simulated. The simulation results are consistent with the experimental data. A bent model of oil-paper insulation is analyzed to study the charge distribution under the actual condition. This paper provides an exploratory research to the simulation of charge phenomenon in oil-paper, and has guiding significance to the design of oil-paper insulation. [ABSTRACT FROM AUTHOR]

Transition metal phosphates with hollow structure have attracted substantial attentions as high-performance electrocatalyst for oxygen evolution reaction (OER). However, these electrocatalytic materials need conductive carrier to realize efficient charge transfer and further improve the OER activity. In this work, ZIF-67 derived hollow NiCo phosphate nanocages supported by waste paper-based carbon aerogel (NCP@WPCA) was prepared as high-efficiency and stable electrocatalyst. Benefited from the enhanced electrochemical active surface area and fast gas emission, the NCP@WPCA catalyst exhibits superior OER activity with low overpotential of 351 mV at current density of 10 mA cm−2, along with good stability in alkaline solution. Additionally, the waste paper-based carbon aerogel as the carrier for electrocatalysts achieves low-cost waste reuse. [Display omitted] [ABSTRACT FROM AUTHOR]

We present the results of a study of the electrical properties of macroscopic free-standing reduced graphene oxide paper (RGOP) with a 60 % fraction of sp 2 ‑carbons at liquid helium temperatures. Graphene domains form an array of quantum dots that determine material properties. At low temperatures, the electrical conductivity of the RGOP can be described by the model of tunneling of charge carriers through a disordered quasi-2D quantum dot array. In the free-standing RGOP at the temperature of 4.2 K, the charge carriers are localized in the quantum dots due to the Coulomb blockade. The effective localization length (~5–8 nm) of charge carriers coincides with the average size of the sp 2 ‑carbon regions (~6–8 nm). The transfer of charge carriers in the RGOP at liquid helium temperatures occurs due to tunneling between energetically close graphene domains, which are not nearest neighbors in space and are rather far from each other (up to ~100 nm). [Display omitted] • Quantum-dot-like charge transfer in macroscopic free-standing RGO paper • Graphene domains array determines electrical properties of macroscopic RGO material. • Strong localization of charge carriers in free-standing RGO paper at low temperatures • Tunneling between energetically close graphene domains that are not nearest neighbors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbohydrate-based fluorometric sensors 1 and 2 have been used to detect picric acid in the aqueous medium. • The detection limits of 1 and 2 for PA were calculated to be 0.094 µM and 0.013 µM, respectively. • The DFT-supported charge transfer and µ-µ interactions explained the fluorescence quenching mechanism. • The sugar moiety plays a role in developing interaction between the sensor and PA in aqueous medium. • Both the sensors were used as naked-eye colorimetric sensors for PA in the test trips. Triazole-linked pyrene-appended inexpensive sensors 1 and 2 were synthesized from carbohydrates to instantly recognize picric acid (PA) based on a charge-transfer mechanism in the semi-water medium. Both sensors showed good selectivity and sensitivity towards PA over a wide variation of nitroaromatics in the absorbance and fluorescence methods. Moreover, sensors 1 and 2 were used for quick finding of picric acids using test strips. Interestingly, it was found that the sensitivity of 2 (LOD: 0.012 µM) is higher than 1 (LOD: 0.093 µM) might be explained by the close intramolecular space of the triazole/sugar residue and pyrene in sensor 2. The fluorescence quenching and structural features of the complexes (1-PA, 2-PA) were supported by density functional theory (DFT) calculations and spectroscopic studies. [ABSTRACT FROM AUTHOR]

The fabrication of S-doped Nb 2O 5 nanostructured thin film coated on carbon fiber paper via sol–gel dip-coating method is described. Upon S-doping, the absorption extends well into the visible region. The resulting S-doped Nb 2O 5 nanostructured thin film is characterized by cyclic voltammetry, X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscope, reflectance spectroscopy (UV–DRS) and thermal analysis (TG–DTG). Electrochemical characterization shows an active electrochemical response indicating an induced charge transfer across the Nb 2O 5/solution interface thus forming two anodic peaks and a cathodic peak. This interesting and significant observation is understood in terms of band bending due to sulfur doping of Nb 2O 5 as well as to the annealing temperature. [ABSTRACT FROM AUTHOR]

Samples of a dried composite oil-paper system were thermally aged in the laboratory under N2 in a sealed container and analysed using their dielectric response. The contributing loss processes were separated using an equivalent circuit model containing constant high frequency capacitances, dc-conductances, a dispersive capacitance, and a low frequency quasi-dc (q-dc) dispersion process as circuit elements. This low frequency dispersion in oil-paper samples is a bulk property of the system that is often mistaken for a dc conduction process when only the imaginary capacitance or ac-conductance is measured. The Dissado-Hill response function is proposed for the frequency dependence of the dispersive capacitance in the mid-frequency range rather than the Debye function because its cluster concepts correlate with the sample morphology of a matrix of oil-filled cavities. The quasi-dc dispersion is assigned to the transport of mobile charges between charge-clusters associated with locally connected oil filled cavities, which is a process that can be represented on a global scale by the form of hierarchical circuit system that leads to constant phase angle responses, and is here modelled by the Dissado-Hill q-dc function. It was found that the two dispersions moved together to higher frequency with thermal ageing of the composite material. The characteristic frequency common to the dispersions had an activation energy that decreased with thermal ageing, whereas their amplitude increased. This behavior is discussed in terms of possible changes to the oil-paper composite caused by the ageing process. [ABSTRACT FROM AUTHOR]

We report for the first time a photothermal paper sensor for the selective and sensitive detection of 2,4,6-trinitrotoluene (TNT) down to 14 ng/cm2. In the presence of TNT, a Meisenheimer complex was formed by means of a charge transfer process from an electron-rich group in polyaniline (PANI) to an electron-deficient nitro group in TNT, which resulted in the near-infrared absorption around 800 nm. Upon irradiation with an 808 nm diode laser, the photothermal effect of the PANI/TNT complex caused the temperature increase, and the temperature difference (ΔT) was proportional to the TNT concentration, while the temperature increase was hardly observed for other nitroaromatics including 2,4-dinitrotoluene (DNT), 2,4,6-trinitrophenol (TNP), and nitrobenzene (NB), affording high selectivity toward TNT. All the tests can be conducted both in solution and on paper. Therefore, the proposed photothermal strategy not only offers a fast and convenient protocol for selective detection of TNT but also indicates great potential in practical applications, especially for airport/railway security inspection and prevention of terrorist attacks. [ABSTRACT FROM AUTHOR]

Cu–Pd bimetallic catalysts were fabricated on carbon paper (CP) by the electrodeposition method via a dynamic hydrogen bubble template approach. At a potential of −1.2 V vs. RHE, the Faradaic efficiency (FE) of C2H4 could reach 45.2% with a current density of 17.4 mA cm−2 in an H-type electrolytic cell. Detailed studies suggest that the enhanced performance of Cu–Pd/CP was attributed mainly to the synergistic effect, low interfacial charge transfer resistance, and the 3D architecture of the catalysts. [ABSTRACT FROM AUTHOR]

A new fluorescent probe ( NDI-5 ) towards Hg 2+ ions has been designed and synthesized based on naphthalene diimide (NDI), which showed extremely weak fluorescence emission in solution owing to the twisted intermolecular charge transfer (TICT) between the NDI core and the receptor. However, upon the addition of Hg 2+ ions, a “turn-on” fluorescence response with red emission was obvious with 32-fold enhancement of the quantum yield, and the detection limit was as low as 1.3 μM. Furthermore, NDI-5 can be applied to MCF-7 cells to realize the detection of Hg 2+ ions in the living systems, and the reversibility with the coordination of KI can be conducted in solution and test stripes for several times. [ABSTRACT FROM AUTHOR]

The surface properties of the anode porous transport layer (PTL) significantly impact the performance of a proton exchange membrane water electrolyzer (PEMWE). The pretreatment (ultrasonic cleaning and acid etching) of a pristine titanium (Ti) felt before it is used as the anode PTL and the surface structural modification of a PTL are two critical methods to improve the performance of an electrolyzer. However, the mechanisms for the pretreatment and surface modification need to be clarified. In this paper, five electrolyzers with five different-fabricated-ways anode PTLs are tested and compared based on I–V curves, EIS curves, and physical characterization techniques. X-ray photoelectron spectroscopy (XPS) results show that the ultrasonic cleaning pretreatment of PTL can improve hydrophilicity by increasing the amount of hydroxyl. In addition, EIS results indicate the significant charge transfer resistance of electrolyzer taking pristine titanium felt as PTL. Adopting the carbon paper as a microporous layer (MPL) or treated titanium felt with acid etching can eliminate or reduce the charge transfer resistance of the electrolyzer. Finally, the mechanism of surface pretreatment and modification of PTL are disclosed to cast light on the improvement of PTLs in further study. • Mechanisms of pretreatments and surface modifications for PTLs are investigated. • Electrolyzers with different-fabricated-ways anode PTLs are tested and compared. • Ultrasonic cleaning strengthens the hydrophilicity of the PTL. • Supplementing MPL or acid pretreatments can improve the anode charge transfer. • Improved mass and electron transport are the reasons for the improved performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Paper-based Cu 2 O photocathode was collaboratively modified with FeOOH and CuS. • Both the charge carrier separation and electron acceptor reduction were promoted. • Dual-hydrophilic-walls hollow channel was used for promoting homogeneous reaction. • Lab-on-paper homogeneous photocathodic bioassay of microRNA was proposed. Herein, a simple but effective photocathodic signal enhancement strategy was developed based on FeOOH/Cu 2 O/CuS photocathode-enabled simultaneous promotion on charge carrier separation and electron acceptor reduction, and applied to construct lab-on-paper homogeneous cathodic photoelectrochemical (PEC) bioassay via dual-hydrophilic-walls hollow channel (DHWHC) design and target-triggered all-in-one hemin@G-rich DNA release. More concretely, FeOOH as hole extraction layer fleetly extracted photogenerated holes from Cu 2 O, while the photogenerated electrons rapidly transferred to CuS, as electron transfer/consumption accelerator, by photoinduced interfacial charge transfer (IFCT), achieving the efficient charge carrier separation. In the IFCT process, the Cu(II) in CuS was reduced to Cu(I) and it could be oxidized back to Cu(II) by electron acceptor (O 2), forming a Cu(II)/Cu(I) redox circular reaction, which could effectively accelerate the transfer/consumption of photogenerated electrons and further promote electron acceptor reduction. Thus, the simultaneous promotion on charge carrier separation and electron acceptor reduction was fulfilled by FeOOH/Cu 2 O/CuS photocathode, producing a strongly enhanced photocathodic signal. On account of the high mass-transfer rates of DHWHC, the mediation of electron acceptor generation through target-triggered hemin@G-rich DNA release, and the proposed signal enhancement strategy, the ultrasensitive lab-on-paper homogeneous PEC microRNA-141 detection was realized with high selectivity, reproducibility, and stability. This work rendered practical guidelines for developing high-performance lab-on-paper cathodic PEC bioanalysis systems. [ABSTRACT FROM AUTHOR]

The rate performance of LiFePO4 batteries is improved by inserting a carbon interlayer, which is synthesized by a simple and cheap pyrolysis of the filter paper commonly used in the laboratories. The specific capacity of the LiFePO4 batteries at low current density is only slightly improved after the introduction of the carbon interlayer, while the specific capacity at high current density is greatly enhanced with a specific capacity of 90 mA h g−1 and 76 mA h g−1 at 10 C and 20 C, respectively, compared to a specific capacity of 17 mA h g−1 and 8 mA h g−1 of LiFePO4 batteries without a carbon interlayer. The improved electrochemical performance is attributed to the porous architecture of the carbon interlayer, serving as a conductive skeleton, largely reducing the charge transfer resistance. [ABSTRACT FROM AUTHOR]

Flexible non-metal oxygen electrodes fabricated from phosphorus-doped graphitic carbon nitride nano-flowers directly grown on carbon-fiber paper exhibit high activity and stability in reversibly catalyzing oxygen reduction and evolution reactions, which is a result of N, P dual action, enhanced mass/charge transfer, and high active surface area. The performance is comparable to that of the state-of-the-art transition-metal, noble-metal, and non-metal catalysts. Remarkably, the flexible nature of these oxygen electrodes allows their use in folded and rolled-up forms, and directly as cathodes in Zn-air batteries, featuring low charge/discharge overpotential and long lifetime. [ABSTRACT FROM AUTHOR]

Highlights: [•] A test paper was used for visualization of explosive 2,4,6-trinitrophenol (TNP) by the naked eye. [•] TNP can strongly quench the phosphorescence of NaGdF4:Ce/Tb nanorods. [•] Polyethylenimine (PEI) molecules facilitate the formation of uniform NaGdF4 nanorods. [•] PEI molecules provide specific recognized sites for TNP by the acid–base pairing interaction. [ABSTRACT FROM AUTHOR]

Strategies for changing the conductivity of Li 2 CO 3 is introduced into the fabrication of Li-CO 2 battery. Benefitting from the favorable hierarchical architecture constructed (CPM-MnO 2), facile charge transfer occurs between catalytic surface and Li 2 CO 3 by –OH⋯O hydrogen bonds improves the metallicity of Li 2 CO 3 , facilitating the formation/decomposition of Li 2 CO 3 and bestowing an ultra-long-term stability of 1087 cycles (4348 h). Taking into account its simplicity, scalable character and outstanding performance, this hierarchical composite electrode paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [Display omitted] • Excellent hierarchical structure of MXene and MnO 2 on carbon paper was fabricated. • Enriched charge transfer occurred on MXene and the MnO 2 by OH⋯O hydrogen bonding. • The prepared batteries showed an ultra-long cycle lifetime and low overpotential. • The optimized electronic structure can improve the metallicity of Li 2 CO 3. • The accelerated decomposition of discharge products promoted CRR and CER kinetics. Lithium-CO 2 batteries are recognized as an essential strategy for efficient carbon sequestration and energy storage to achieve carbon neutrality. Their cycle-ability and polarization voltage, however, are hindered by high decomposition voltage (≈4.3–4.5 V) of insulating Li 2 CO 3. Herein, we report a significant advance toward the rational design of self-supporting and ultra-long cycle lifetime cathode for Li-CO 2 batteries, dependence on a favorable hierarchical architecture and rich charge transfer constructed by homogeneously distributed MnO 2 nanoplates rooted in the MXene surface supported by carbon paper. Detailedly, it exhibits impressive ultra-long-term stability of 1087 cycles (4348 h) with a low polarization gap (≈ 0.47 V) at a high current of 200 μA cm−2, which is outperformed by all the liquid electrolyte-based Li-CO2 batteries reported previously. Electronic structure analysis reveals that facile charge transfer occurs between catalytic surface and Li 2 CO 3 , springing from the –OH functional group (in MXene) to MnO 2 by –OH⋯O hydrogen bonds, which acts as charge transfer channels, improving the metallicity of Li 2 CO 3 and facilitating its decomposition and extending battery cyclability. This work paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [ABSTRACT FROM AUTHOR]

Due to the inherent toxicity of cadmium selenide (CdSe)‐based quantum dots (QDs), Cd‐free alternatives are being widely investigated. Indium phosphide (InP) QDs have shown great potential as a replacement for CdSe QDs in display applications. However, the performance of InP‐based quantum dot light emitting diodes (QLEDs) is still far behind that of the CdSe‐based devices. In this study, we wanted to show the effects of different approaches to improve the performance of InP‐based QLED devices. We investigated the effect of magnesium (Mg) doping in ZnO nanoparticles, which is used as an n‐type electron transport layer, in balancing the charge transfer in InP‐based QLED devices. We found that an increasing Mg doping level can broaden the ZnO band gap, shift its energy levels, but most importantly, increase its resistivity; as a result, the electron current density is significantly reduced and the device efficiency is improved. We also investigated the effect of high‐photoluminescence quantum yield emitters and different QLED architectures on the device performance. Through optimizing QD structures and devices, red InP QLEDs with the current efficiencies reaching 11.6 cd/A and green InP QLEDs with the current efficiencies reaching 37.0 cd/A were fabricated. [ABSTRACT FROM AUTHOR]

The synergistic effects derived from optimizing the chemical and structural features of electrocatalysts permit them to attain remarkable activity and stability. Herein, 1D/2D cobalt‐based nanohybrid (CoNH) electrodes are developed; the structural design consists of Co3O4 electrospun nanoribbons (NRs) deposited onto a carbon fiber paper substrate where Co3O4 nanosheets are subsequently grown via an electrodeposition step and UV/ozone treatment. The content of noncovalently functionalized carbon nanotubes within the Co3O4 NRs is first tuned to enhance their charge transfer properties and mechanical stability. The electrocatalytic activity of the electrodes is further improved by a phosphorus modification of the 1D NRs, resulting in the formation of NaCoPO4. The optimized 1D/2D CoNH electrode, i.e., ED‐0.09 wt% fCNTs/P‐CoNHs, displays a similar performance to that of platinum in 0.25 m Na2S/0.35 m Na2SO3 (Tafel slope ≈102 mV dec−1 for the former and ≈96 mV dec−1 for the latter) and outstanding stability for up to 48 h. The versatility and high activity of this electrode is also demonstrated according to tests in a conventional water splitting system (cell voltage 1.55V, to produce 10 mA cm−2) and a solar‐driven electrolyzer (1 m KOH). [ABSTRACT FROM AUTHOR]

Dealloyed Cu@Pt core-shell electrocatalyst was fabricated by cyclic co-electrodeposition and selective Cu dealloying (CCEd-sCuD) on carbon paper (CP), namely Cu@Pt/CP. The Cu@Pt/CP exhibited a core-shell structure comprising with a Cu-rich core and a Pt-rich shell. The crystalline phases of Pt/CP and Cu@Pt/CP were a face-centered cubic (fcc). The compressive lattice strain approximately 0.85% was found in the Cu@Pt/CP owing to a lattice mismatch between a core and a shell region. In the core-region, Cu was formed Pt-Cu alloy as major and copper oxide and also metallic copper as minor. The morphology and grain size of the Cu@Pt/CP displayed a porous spherical shape with 100 nm in diameter, while those of Pt/CP seemed to be a cubic shape with smaller diameter of 40 nm. In electrochemical and catalytic activity, the surface of Cu@Pt/CP had a larger electrochemical active surface area (ECSA) than that of Pt/CP due to a porous formation caused by Cu dealloying. It is not surprising that the Cu@Pt/CP showed higher catalytic activity and greater stability towards 0.5 M 2-propanol electrooxidation in 0.5 M H 2 SO 4 in terms of peak current density (j p ), peak potential (E p ), onset potential (E onset ), diffusion coefficient ( D ), and charge transfer resistance (R ct ) which were caused by electronic structure modification, higher compressive lattice strain, and larger ECSA, compared with Pt/CP. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we evaluate the potentiality of high-k materials (Al2O3, HfO2 and HfAlO) for interpoly application in non-volatile memories. A study of the leakage currents of high-k based capacitors allowed to discuss the retention performances at room and high temperatures of high-k interpoly dielectrics. High-k materials are then integrated as control dielectrics in silicon nanocrystal and SONOS (Si/SiO2/Si3N4/SiO2/Si) memories. The role of the high-k layer on the memory performances is discussed; a particular attention being devoted to the retention characteristics. Analytical models, combined with experimental results obtained on various structures allowed to analyze the mechanisms involved during retention. [Copyright &y& Elsevier]

• Dendritic In-doped Cu@Cu 2 O catalyst is prepared by co-electrodeposition method. • Doped-In content can tailor Cu+/Cu0 ratio, charge distribution, morphology and ECSA. • Cu+/Cu0 ratio plays a vital role on enhancing FE CO and partial current density at low In doping. • 3.7% In-Cu sample shows the highest FE CO of 87.6 ± 2.2 % and j CO of 9.7 ± 1.04 mA cm -2. Element doping is an effective strategy to enhance the selectivity of electrochemical carbon dioxide reduction. In this work, a dendritic core-shell In-doped Cu@Cu 2 O catalyst is prepared by co-electrodeposition method on carbon fiber paper for selective electroreduction of CO 2 to CO. Faradaic efficiency of producing CO over this dendritic In-doped Cu@Cu 2 O reaches 87.6 ± 2.2% with total current density of 11.1 ± 0.85 mA cm−2 at −0.8 V vs RHE, which outperforms most of the reported Cu-based electrocatalysts. The excellent performance is mainly derived from charge re-distribution and the enhanced intrinsic activity due to the formation of In-doped Cu 2 O layer. Meanwhile, the Cu+/Cu0 can be adjusted by tailoring the doped-In content. The relatively high ECSA and small charge transfer resistance are also conducive to improve the selectivity and activity. The oxyphilic In metal incorporated into the copper lattice can well stabilize the intermediate *COOH through enhancing interaction with O-ends of *COOH. This work provides a facile approach and a deep insight on design and synthesis of high efficiency hybrid electrocatalysts. [ABSTRACT FROM AUTHOR]

• A novel paper electrochemical platform modified with quantum dots is presented. • CdSe/CdS magic-sized quantum dots (MSQDs) were used to improve the sensitivity. • MSQDs present several advantages in comparison with traditional quantum dots. • This is the first report regarding the use of MSQDs for electroanalytical purposes. • The modified sensor was successfully applied for dopamine sensing in human serum. A novel and disposable electrochemical platform is presented in this work. The paper electrochemical device (PED) developed here consists of a simple and inexpensive three-electrode system drawn over a tracing paper substrate. The graphite working electrode (5 mm diameter) was modified with CdSe/CdS magic-sized quantum dots (MSQDs) to improve the sensitivity. To the best of our knowledge, this is the first full report of the analytical use of MSQDs for modification of electrochemical sensors. This modified electrode was fully characterized and optimized. The best results were obtained when 10 µg MSQDs were deposited over the electrode surface. This proportion provided an amplification of ca. 46% in the peak currents in comparison with the bare electrode, besides decrease the charge transfer resistance and increase the electroactive area of the sensor. Furthermore, the quantum dots-based sensor presented good stability, repeatability and reproducibility (relative standard deviations were ca. 7.2% or less regarding the peak currents). The analytical suitability of this electrochemical platform was demonstrated by detecting dopamine using differential pulse voltammetry. The analyte presented great electrochemical activity over the surface of the modified electrode and the signal showed dependence on the concentration range from 0.5 to 15 µmol L −1. The limit of detection achieved (96 nmol L −1) was lower than those stated in other recent reports that use more expensive and complex electrochemical systems. Lastly, the platform was successfully employed for the sensing of dopamine in human blood serum samples with recovery rates between 95.2 and 102.6%. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• Oxidation of phosphomolybdate is successfully used in phosphate quantification. • Reusable SPEs have potential for high sample analysis load of lab phosphate tests. • Paper polished SPEs significantly increase the phosphate sensitivity response. • Successive uses of paper polished SPEs do not affect anodic charge transfer coefficient. • Performance of paper polished SPEs shows suitability in soil phosphate tests. Carbon screen-printed electrodes (SPEs) are recognized as disposable, single-use, and inexpensive sensors to measure various analytes, including phosphates. SPEs have multiple applications using cyclic voltammetry (CV), which is a powerful electrochemical technique used to investigate the redox reactions of specific analytes. However, high demand for SPEs in laboratories creates questions about their economical feasibility and disposal after a single-use, while it has been found that polishing the surfaces of SPEs shows potential for reuse. The aim of this study was to examine the effect of polishing SPEs using office paper on their reproducibility, repeatability, and amperometric response for phosphate electrochemical sensing. The effect was determined by measuring the peak currents of the CV scans of phosphate analytes before and after SPE polishing. The sensitivity, limit of detection, and reproducibility of the electrochemical phosphate test were significantly improved by polishing the SPEs with office paper. For example, the paper polished SPEs increased the phosphate sensitivity response by 63.6% and showed reuse efficacy up to successive 20 CV cycles. Compared to carbon pretreatment methods that use chemicals in SPE mechanical polishing, the proposed paper polishing method is eco-friendly, cost-effective, and shows great promise towards more sustainable phosphate tests. [ABSTRACT FROM AUTHOR]

This document, titled "Intermolecular Charge Transfer for High-Performance Organic Light-Emitting Diodes," discusses the use of thermally activated delayed fluorescence (TADF) materials in organic light-emitting diodes (OLEDs) to achieve high-performance devices. Specifically, the authors designed and synthesized two new molecules, CzPh-1 and CzPh-2, which were found to form deep-blue exciple emission with a triazine-containing molecule, CzTrz, through effective intermolecular charge transfer. The photoluminescence spectra and time-resolved photoluminescence studies demonstrated the TADF characteristics of these materials. The authors acknowledge the support from the National Natural Science Foundation of China and the China Postdoctoral Science Foundation. [Extracted from the article]

Three of the primary bottlenecks, which should be consider for practical, point-of-need use of microbial fuel cell (MFC) analytical devices were surpassed in this work: i) the use of a diffusive barrier, hence, an electrogenic biofilm; ii) longer enrichment/stabilization times to produce a biofilm, made in a laboratory environment, over the electrode; and iii) difficulty comparing results obtained from MFCs based on electrogenic biofilms with standardized bioassays, a setback to be adopted as a new method. Here we show an easy way to determine water toxicity employing planktonic bacteria as biorecognition agents. The paper-based MFC contain an electron carrier (or mediator) to facilitate charge transfer from bacteria to the anode. In this way, there is no need to use biofilms. As far as we know this is the first paper-based MFC containing P. putida KT2440, a well characterized non-pathogenic bacteria previously used in standardized water toxicity bioassays. Results were obtained in 80 min and an effective concentration 50 of 9.02 mg L−1, calculated for Zn2+ (a reference toxic agent), was successfully compared with previously published and ISO standardized bioassays, showing a promising future for this technology. The practical design and cost (less than one U.S. dollar) of the paper-based MFC toxicity test presented will open new market possibilities for rapid and easy-to-use MFC analytical devices. Image 1 • A mediated paper-based MFC toxicity test is presented for the first time. • A new strip-based design comprising disposable and low cost materials was used. • Toxicity tests performed with paper-based MFCs produced results in less than 80 min. • Zn2+ toxicity evaluated with paper-based MFC is consistent with standard bioassays. [ABSTRACT FROM AUTHOR]

Facile fabrication of green fluorescent GSH-AuNCs@His via LMCT charge transfer and used as highly slective and sensitive probe for the detection of Pb2+ ion. • Fabrication of green luminescent GSH-linked AuNCs@His via ligand-metal charge transfer phenomenon. • Ultra-small NCs for the quantification of Pb2+ ion in water and plasma samples without further treatment. • High sensitive and selective detection limit of 1 nM with linear range of 5.0−1000 nM for Pb2+ ion. • GSH-AuNCs@His-modified cellulose paper for in situ detection of Pb2+ ion. The ultra-small size, excellent photo-stability, and tremendous fluorescence properties make the gold nanoclusters (AuNCs) as novel chemo- and biosensors. Herein, a one-pot approach was implemented for fabricating highly fluorescent AuNCs using histidine (His) and glutathione (GSH) as a reducing and protecting agent. As-synthesized GSH-AuNCs@His exhibits bright green fluorescence with excitation and emission peak of 420 and 502 nm, respectively, with a quantum yield of 7.5 %. The GSH conjugated with law fluorescent AuNCs@His through the free amines of His, and then utilized for the nanomolar detection of Pb2+ ion in aqueous solution via selective fluorescence turn-off mechanism with linear concentration range 5.0−1000 nM. The detection limit for Pb2+ ion was calculated 1.0 nM, which is much lower than the allowed concentration of Pb2+ ion in drinking water. The synthesized GSH-AuNCs@His was applied to Pb2+ ion within the spiked plasma sample and obtained excellent recovery with good precision and accuracy. The study also presents chemically modified cellulose paper strips with the conjugated GSH-AuNCs@His for the detection of Pb2+ ion. [ABSTRACT FROM AUTHOR]

A theory of control of cellular proliferation and differentiation in the early development of metazoan systems, postulating a system of electrical controls “parallel” to the processes of molecular biochemistry, is presented. It is argued that the processes of molecular biochemistry alone cannot explain how a developing organism defies a stochastic universe. The demonstration of current flow (charge transfer) along the long axis of DNA through the base-pairs (the “π-way) in vitro raises the question of whether nature may employ such current flows for biological purposes. Such currents might be too small to be accessible to direct measurement in vivo but conduction has been measured in vitro, and the methods might well be extended to living systems. This has not been done because there is no reasonable model which could stimulate experimentation. We suggest several related, but detachable or independent, models for the biological utility of charge transfer, whose scope admittedly outruns current concepts of thinking about organization, growth, and development in eukaryotic, metazoan systems. The ideas are related to explanations proposed to explain the effects demonstrated on tumors and normal tissues described in Article I (this issue). Microscopic and mesoscopic potential fields and currents are well known at sub-cellular, cellular, and organ systems levels. Not only are such phenomena associated with internal cellular membranes in bioenergetics and information flow, but remarkable long-range fields over tissue interfaces and organs appear to play a role in embryonic development (Nuccitelli, 1992). The origin of the fields remains unclear and is the subject of active investigation. We are proposing that similar processes could play a vital role at a “sub-microscopic level,” at the level of the chromosomes themselves, and could play a role in organizing and directing fundamental processes of growth and development, in parallel with the more discernible fields and currents described. [ABSTRACT FROM AUTHOR]

Abstract: Flash memory, in particular NAND, has been an enabling technology for portable applications for the last two decades. The strength of Flash is its excellent scaling capability, allowing an ever increasing density at a decreasing cost and maintained reliability. However, the geometrical scaling of the cell exacerbates charge loss and fluctuation effects. On the other hand, new post-Flash memory technologies are being proposed, with different storage concepts and reliability physics. This review discusses the major reliability issues for Flash, with emphasis on the physical mechanisms and modeling. The reliability of charge trap and resistive memories, such as phase change and resistive switching memories, is addressed. [Copyright &y& Elsevier]