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A facile method is proposed in this work to prepare a carbon paper (CP) with outstanding properties by doping boron to catalyze graphitization at lower temperature. Boron was introduced into CP by impregnating carbon fiber preform into a boron/phenolic resin/ethanol solution, and then CP was obtained after the consecutive procedures of hot pressing, carbonization, and graphitization. Morphology, microstructure, composition, and physical properties of the doped and undoped CPs were thoroughly investigated via various techniques to exam the effects of boron concentration and graphitization temperature. Furthermore, the boron doped CP was fabricated into fuel cell gas diffusion layer (GDL) and membrane electrode assembly (MEA) to evaluate its performance through the single cell performance. The findings indicated CP doping with 2 wt% boron could lower the graphitization temperature by at least 200 °C. The B-doped GDL had a higher power density in comparison with the undoped GDLs made in our lab or from the commercial brands. • The innovative preparation method for carbon paper with high conductivity. • The effect of boron concentration and graphitization temperature on carbon paper. • The single cell performance of B-doped gas diffusion layer. [ABSTRACT FROM AUTHOR]

A noble-metal-free bifunctional electrocatalyst with outstanding activity and stability is of great importance for the development of rechargeable zinc-air batteries (ZABs). Herein, we employed a facile strategy to fabricate nitrogen-doped NiCo 2 O 4 nanostructures on carbon paper as a binder-free air cathode for rechargeable ZABs. An optimized process of nitrogen plasma treatment has enhanced the electrical conductivity of the metal oxide and induced abundant active sites into the crystal structures, resulting in enhanced electrocatalytic activities toward oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Notably, mild plasma treatment leads to efficient N doping while the morphology and specific surface area of the catalyst both remain unchanged. The air cathode with NiCo 2 O 4 doped with nitrogen in 2 min plasma treatment and integrated into a zinc-air battery with liquid electrolyte provided a small charge-discharge voltage gap and distinguished cycling stability superior to the air cathode with noble-metal catalyst counterparts. Furthermore, the solid-state zinc-air battery with this material displays excellent stability with just a small increase of the charge-discharge voltage gap over 20 h of operation. This work illustrates the promising potential of plasma treatment in the fabrication of high-performance catalysts. • N-doped NiCo 2 O 4 was prepared by hydrothermal method and N 2 plasma treatment. • Mild plasma treatment leads to efficient N doping in NiCo 2 O 4. • NiCo 2 O 4 with N 2 plasma treatment of 2 min exhibits excellent OER/ORR performances. • N–NiCo 2 O 4 -2 min worked as a binder-free air cathode in Zn-air batteries. [ABSTRACT FROM AUTHOR]

Developing new forms of flexible zinc–air (Zn–air) batteries is crucial to economic growth. Nevertheless, the absence of an oxygen evolution reaction catalyst with high catalytic efficiency and low-cost causes instability of Zn–air battery cycling and economic unviability, respectively. In this paper, a leaf-like N-doped carbon structure with CoS2 nanoparticles self-supported on carbon fiber paper (CoS2-CZ@CFP) was developed as an air electrode for Zn–air batteries, which not only uses nonprecious metal elements, but also has a self-supporting configuration, enhancing the contact between the catalyst and electrode while facilitating the transfer of electrons. Sulfur as the source gas was introduced into Co-doped metal–organic skeletons (Co-ZIFs) anchored on carbon fiber paper (CFP) for in situ vulcanizing transition metal Co, which successfully ensures the uniform distribution of sulfide particles in the carbon matrix, hence enriching active catalyst sites. The CoS2-CZ@CFP demonstrated an overpotential of 1.611 V at J = 50 mA cm−2, superior to RuO2@CFP (1.814 V). A Zn–air battery fabricated using the synthesized CoS2-CZ@CFP exhibited an extended life cycle of 117 h. This research paves the way for a novel method of designing self-supporting configurations of sulfides and carbon matrix composites as promising air electrodes applicable to Zn–air batteries. [ABSTRACT FROM AUTHOR]

Persulfate is a potential oxidant in direct liquid fuel cells (DLFCs), and the commercial carbon paper (CP) can directly serve as the cathode due to strong oxidizability of persulfate. However, the poor catalytic activity and low specific surface area of CP limit the electrode performance. Herein, a defect-enriched, pyridine-N-dominated and self-standing carbon paper electrode with abundant carbon nanosheets is successfully prepared by hydrothermal treatment combined with in-situ electrochemical exfoliation. Benefitting from the integrated structure, plentiful defects and high-content pyridine-N dopants of the prepared electrode result in the superior electrocatalytic activity and long-term stability in persulfate reduction reaction. Remarkably, a membraneless DLFC with the prepared electrode as cathode and persulfate as the oxidant acquires prominent cell performance and extremely high open circuit voltage of 2.13 V. The maximum power density of the DLFC achieves 241.0 mW cm−2, far higher than those of the previously reported similar membraneless DLFCs. A three-dimensional computational model for the DLFC is developed, which is help to reveal the importance of improving the reaction kinetics and electrical conductivity for the cathode with persulfate as oxidant. A facile approach for in-situ preparation of highly N-doped CP electrode is provided to yield outstanding cell performance for low-cost DLFCs. [Display omitted] • A facile way to introduce high-content nitrogen on carbon paper is proposed. • Massive defective sites, carbon nanosheets and pyridine-N dopants are introduced. • N doping enhances charge transfer and electrocatalytic activity of the electrode. • Effects of hydrothermal duration and precursor concentration are discussed. • The N-doped cathode yields the outstanding cell performance for low-cost DLFC. [ABSTRACT FROM AUTHOR]

The increasing volume of paper mill sludge (PM) and municipal solid waste (MW) poses environmental problems associated with heavy metals. Co-pyrolysis of PM/MW with additives effectively reduces the risk of heavy metal contamination. In this study, co-modified vermiculite (LMV) was prepared using the modification methods of intercalation-exfoliation, Mg2+ impregnation, and thermal activation. PM and MW were mixed at different doping ratios, and a non-doping experiment was performed to compare the pyrolysis processes and the retention rates for different heavy metals (Zn, Cr, Cu, Cd, and Pb), as well as the potential ecological risks, and the form distribution of the heavy metals. The addition of LMV reduced the risk posed by heavy metals. In the absence of doping, a higher pyrolysis temperature is conducive to an increase in the oxidizable and residual fractions of heavy metals without higher retention rates. Among these heavy metals, Zn, Cr, and Cu had higher retention rates and low risks, whereas Cd had a relatively high risk with low retention rates. Simulations showed that there was a transfer of the Mulliken charge after the reaction, indicating that all the heavy metals can interact with O, Al, and Si in the LMV; this reaction mainly occurs around the No. 17 O atom of the LMV. The monomers, oxides, and chlorides of Zn/Cr/Cu exhibited better adsorption on vermiculite compared to that of Pb/Cd. [Display omitted] • HMs can be controlled well in PM/MW pyrolysis in fluidized bed by LMV • The addition of LMV can reduce HMs risk and improve HMs forms. • Dopping of PM/MW is not beneficial to hazards reduction of HMs. • HMs react with LMV are mainly concentrated around the No. 17 O atom. • The reactivity of Cr/Zn/Cu with LMV is stronger than those of Cd/Pb. [ABSTRACT FROM AUTHOR]

Sulphur doped graphitic carbon nitride (SGCN) was effectively prepared and comprehensively described. A straightforward synthetic process based on thermal condensation was reported for the synthesis of SGCN using thiourea as a precursor. Cyclic voltammetry (CV) and differential pulse voltammetry were used to evaluate the electrochemical performance of cortisol. SGCN sheets were used to boost the electro-catalytic activity, exhibiting very exceptional electrochemical behaviour towards cortisol. As a result, we obtained a broad linear response range of 0.1–100 μM, as well as a comparatively low detection limit (15.8 × 10−8 M). Furthermore, the fabricated SGCN/CFP electrode shows excellent selectivity in the presence of a large number of possible interfering species. SGCN comprises (C with N and S) heteroatoms, which most likely would have led to a better current response towards cortisol detection. Furthermore, the structural defects that generate additional active sites on the surface of SGCN may enhance the quick electron transfer that occurs during the oxidation of cortisol. [ABSTRACT FROM AUTHOR]

A highly selective solid-state fluorescent sensor based on N-doped carbon quantum dots (N-CQDs) and cotton fiber paper (CFP) is reported for the determination of trace mercury (II)(Hg2+). The N-doped carbon quantum dots on cotton fiber paper (N-CQDs@CFP) was synthesized using a facile one-step microwave hydrothermal method. Multiple approaches were employed to fully investigate the morphology and chemical structure of the paper-based fluorescent sensor. The N-CQDs were chemically bonded onto the CFP, which offers good reproducibility and stability of the sensor. The N-CQDs@CFP showed high-intensity blue emission in dark-field imaging, and the fluorescence was quenched by Hg2+. The Hg2+ in aqueous samples was easily determined and visually monitored. There was good linearity from 0 to 250 μM, and the limit of detection was 34 nM. The paper-based fluorescent sensor provided accurate and rapid determination of Hg2+ upon comparison with flame atomic absorption spectrophotometry (FAAS). The simple preparation, rapid detection (< 5 min), low cost, and easy-handling illustrate that the reported sensor has a significant value in environmental monitoring. [ABSTRACT FROM AUTHOR]

Integrating more active components into a catalyst material could facilitate the development of multifunctional electrocatalysts for energy conversion and storage applications. In this study, we developed a multifunctional electrocatalyst, namely, Pd alloyed with Co-Fe deposited on N-doped mesoporous carbon derived from tissue paper (Pd@Co-Fe/N-TDC). The synergism in Pd@Co-Fe/N-TDC, stemming from the interatomic alloy between Pd and Co-Fe, N-doped mesoporous carbon with defective surfaces, distribution of polyhedral Pd nanoparticles, and strong metal-support interfacial interaction, resulted in significantly high electrocatalytic performance for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Pd@Co-Fe/N-TDC was found to be an efficient bifunctional oxygen electrocatalyst, and this was evidenced by a high onset potential (1.01 V) and kinetic current density (2.6 mA/cm2) for the ORR and by a low overpotential (296 mV) and a low Tafel slope value (38 mV/dec) for the OER, along with a small Δ E of 736 mV. The catalyst also exhibited high durability for both ORR and OER, even after 10000 and 5000 cycles, respectively. Theoretical assessment provides an insight into the synergism of active metal sites in Pd@Co-Fe/N-TDC, which showed its potential for use as a non-Pt electrocatalyst for energy applications. [ABSTRACT FROM AUTHOR]

To enhance the thermal–mechanical properties of insulating paper, nano-fibrillated cellulose (NFC) was used to dope cellulose. The mechanical strength and thermal stability of cellulose insulating paper with different NFC doping mass fractions were analyzed by molecular dynamics simulations and experiments, and the optimal doping ratio of NFC was determined. The results showed that the mechanical properties, thermal conductivity, thermogravimetric properties, and glass transition temperature of NFC-modified insulating paper were improved compared with ordinary insulating paper. Among them, the maximum tensile strength after doping was 58.147 MPa, which was 20.040 MPa higher than the 30.107 MPa of the insulating paper before modification. The glass transition temperature was also 8.54 °C higher than the 127.05 °C before modification. Meanwhile, the mechanism of NFC doping enhancement on the insulating paper's thermal–mechanical properties was analyzed from the aspects of cohesive energy density, fractional free volume, hydrogen bond, and mean square displacement. We believed that the doping of NFC can improve the thermal–mechanical properties of the insulating paper because it could enhance cellulose's interchain force, fill the insulating paper's internal pores, and increase the hydrogen bonding energy. The thermal–mechanical properties of cellulose insulating paper with different NFC doping mass fractions were analyzed to determine the optimal doping ratio of NFC through molecular dynamics simulations and experiments. Meanwhile, the mechanism of NFC doping enhancement on the insulating paper's thermal–mechanical properties was also investigated from the aspects of cohesive energy density, free volume fraction, hydrogen bonding, and mean square displacement. [ABSTRACT FROM AUTHOR]

The design of light‐responsive color switching systems (LCSs) is essential to the implementation of rewritable paper and oxygen detection. Previous LCSs rely on metal‐based semiconductor photocatalysts which are expensive and pose metal‐leaking risk. To solve the issue, for the first time, nitrogen‐doped carbon quantum dots (N‐CQDs) are reported as metal‐free photocatalyst for visible photoprinting and oxygen sensing. On N‐CQD surface, the decorated amino and hydroxyl groups act as hole scavengers and thus realize visible‐light‐responsive single and multiple color switching, after mixing with redox‐sensitive dyes. Combined with polymeric substrates, LCS rewritable papers can be fabricated and exhibit rapid decoloration performances under 420 nm light irradiation, due to the reduction of dye by photogenerated electrons from N‐CQDs. After the decoloration, efficient color reversion can be realized by the oxidization of dye in ambient air (O2). By taking advantage of the controlled recoloration kinetics, an oxygen sensor can be attained for visual quantitative analysis of atmospheric conditions with color variations. These results assist the future development of nonmetal color switching systems for superior functional design of photoprintable papers and colorimetric oxygen sensors. [ABSTRACT FROM AUTHOR]

Three specific catalysts, namely ZIF-67 (zeolitic imidazolate framework-67), Co@NCF (Co@Nitrogen-Doped Carbon Framework), and 3D NCF (Three-Dimensional Nitrogen-Doped Carbon Framework), were prepared and studied for pulp and paper mill effluent degradation using heterogeneous activation of peroxymonosulfate (PMS). Numerous characterizations, including scanning electron microscopy (SEM), X-ray diffraction (XRD), and N 2 adsorption, were used to characterize the properties of three different catalysts. 3D NCF is remarkably effective at heterogeneous activation of PMS to generate sulfate radicals to degrade pulp and paper mill effluent (PPME) compared to the other as-prepared catalysts. The catalytic activity reveals a sequence of 3D NCF > Co@NCF > ZIF-67.3D NCF could degrade organic pollutants in 30 min at an initial COD concentration of 1146 mg/L of PPME, 0.2 g/L catalysts, 2 g/L PMS, and 50 °C. Consequently, it was observed that the degradation of PPME using 3D NCF followed first-order kinetics, with an activation energy of 40.54 kJ mol−1. Overall, 3D NCF/PMS system reveals promising performance for PPME removal. • 3D NCF synthesized via calcining and etching a zeolitic imidazolate framework (ZIF-67). • 3D NCF presented the highest activity in the pulp and paper mill effluent degradation. • 3D NCF proved to be a promising catalyst and has superior stability. • Pulp and paper mill effluent degradation on 3D NCF followed pseudo-first-order kinetics. [ABSTRACT FROM AUTHOR]

Wearable electronic energy storage devices usually require the integration of flexible mechanisms and uncompromising electrochemistry of lithium-ion batteries (LIBs). Most of the studies in this field have mainly focused on enhancing the electrochemical properties of the material, while the significance of its flexibility and mechanical properties has been relatively ignored. In this study, the 20 wt % carbon fibers (CFs) composite N-doped flexible carbon nanofiber paper (NFCFP) was prepared through a facile PFI refiner and Bauer sieve of pulping and papermaking machinery sieve-assisted methods combined with annealing technology. The NFCFP-700 with high pyridine N content shows good ion transport and storage performance, the specific capacity remained 308 mAh⸱g−1 after 100 cycles at 0.1 C, and even at 1 C, the specific capacity of the electrode material instead increases constantly at 142 mAh⸱g−1. According to density functional theory (DFT) calculations, the coexistence of pyridine N content and defects in carbon materials was found to enhance the adsorption energy (E ad) of lithium, and the N4V2 locally show the most negative electrostatic potential (ESP) distribution, which was more favorable for the adsorption of Li+ being positively charged. This insight from DFT studies combined with experimental data emphasizes the favorable impact of pyridine N content and defects on the lithium adsorption process in carbon materials, also providing valuable information for the design and optimization of materials for lithium storage applications. [ABSTRACT FROM AUTHOR]

Constructing low-cost, high-catalytic-performance anode electrocatalysts is a significant challenge for methanol oxidation (MOR) and urea oxidation (UOR) reactions. Using paper templates with abundant pores to prepare thin porous metal materials helps to obtain high-performance electrode materials. The nano amorphous B-doped Ni/crystalline Ni (nanoam Ni-B/Ni) foil composite electrodes were derived from paper templates prepared by impregnation, high-temperature reduction, and electrodeposition methods. Porous Ni foils (Nip) derived thinnest rice ("Xuan") paper, initially used for Chinese calligraphy and painting, exhibits the best performance due to its strong adsorption and wettability. Compared to direct current electrodeposition, pulse electrodeposition yields finer amorphous B-doped Ni nanoparticles with good catalytic performance. Under a current density of 100 mA·cm−2, the nanoam Ni-B/Ni composite electrode prepared under a duty cycle of 0.5–1.0 s achieved current densities of 290.4 mA·cm−2 (MOR) and 340.4 mA·cm−2 (UOR) at 0.8 V, which are improved by 37.1% and 55.1%, respectively, compared to those of Nip. After 2000 cycles, with solution replacement, the current densities maintained 99.2% (MOR) and 81.6% (UOR) of the original values, showing excellent electrocatalytic stability. This research provided a new use for Chinese rice paper, and the prepared Nip-based electrode, with a thickness of about 60 μm and a low area quality, had a simple preparation process and good electrochemical properties, and can be used as a potential substitute for commercial Ni foam for portable or small electrochemical devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple synthesis method has been developed for Ag@ZIF-8, involving controlling the loading and size of Ag NPs. • Ag@ZIF-8 meet the requirements for antibacterial agent used in the melamine-impregnated paper. • The multiple synergistic antibacterial mechanism of Ag@ZIF-8 was verified. • The decorated blockboards with 0.20 wt% Ag@ZIF-8 reached Level Ⅰ antibacterial grade. Melamine-impregnated paper, a decorative material in furniture and interior design, could potentially impede the spread of indoor bacteria if it possesses antibacterial properties. Here, nano Ag-doped ZIF-8 (Ag@ZIF-8) was synthesized using ion exchange and in-situ chemical reduction strategies, followed by incorporating it into melamine-impregnated paper. The ion exchange mechanism of Zn2+ and Ag+ during ion exchange reactions was investigated. The structure of Ag@ZIF-8 was well-defined, with Ag nanoparticles evenly distributed on the surface of ZIF-8. Ag@ZIF-8 showed good thermal stability at 400 °C, meeting the requirements for the hot-pressing process of the melamine-impregnated paper. Ag@ZIF-8 exhibited enhanced ROS generation under visible light compare to ZIF-8, which was attributed to its reinforced light absorption and charge carrier separation facilitated by the localized surface plasmon resonance (LSPR) effect. The antibacterial activity of Ag@ZIF-8 was better than ZIF-8, owing to the multiple-synergistic antibacterial mechanisms of the ion release and ROS generation. Specifically, the 10-Ag@ZIF-8 exhibited MIC of 128 μg/mL and 64 μg/mL against E. coli and S. aureus , respectively. The signal intensity of •O 2 − induced by 10-Ag@ZIF-8 was 4.38 times higher than that of ZIF-8. As the addition of Ag@ZIF-8 increased, the antibacterial performance of melamine-impregnated paper improved. Considering the antibacterial property and economy of melamine-impregnated paper, 0.20 wt% was the optimal amount for 10-Ag@ZIF-8 decorated blockboard. This study proposes a novel approach for synthesizing MOF-based melamine-impregnated paper with antibacterial properties, aiming to reduce bacterial spread, minimize disease risks, and contribute to lowering overall healthcare costs. [ABSTRACT FROM AUTHOR]

This paper demonstrates the development and efficiency of a portable paper-based electrochemical sensor for determining amperometric L-cysteine levels with a personal glucometer (PGM). An electrochemical microfluidic paper-based analytical device (EmPAD) was designed as a glucometer test strip. For the fabrication of the EmPADs, chromatography paper was used as the substrate. A wax pencil was used to create a hydrophobic wall and hydrophilic channels. Also, graphene ink, Ag ink, and carbon ink were used to make the reference electrode and the working electrode by a screen printed method. (3-Aminopropyl) triethoxysilane (APTES)-SBA-16 was synthesized and characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), and scanning electron microscopy (SEM) techniques. The (APTES)-SBA-16 was added to the hydrophilic part to increase hydrophilicity. Ag/SBA-16 was added to modify the graphene electrode. The modified electrode exhibited good catalytic activity to oxidize L-cysteine. Our test strip made with a glucose meter and an amperometric readout is affordable and easy to use for in situ cysteine measurement at the point of care. The linear range of the calibration curve and the detection limit (S/N=3) was between 0.1 to 250 µM and 0.02 µM. The recoveries for the human urine samples analysis were in the range of 96%–110% for Cys. [ABSTRACT FROM AUTHOR]

To further enhance the performance of nano-silica modified M-phenylene isophthalamide (MPIA) insulation paper, nano-SiO2 particles are modified by 3-aminopropyltriethyloxy silane (APTS) surface into meta-aramid insulation paper to form grafting nano-silica particles (GNP). In order to find the relative best performance of the nanoparticle doping ratio, molecular dynamics simulations were used to study the effect of different GNP volume fractions on the mechanical parameters of the MPIA amorphous region, and the highest mechanical performance was obtained with a volume fraction of 9.4 vol. %. Under this doping condition, the interaction between GNP and MPIA fibers was enhanced by the formation of a large number of hydrogen bonds. The addition of GNP decreased the diffusion of water, acid and gas in MPIA fibers and the influence of these substances on the thermal stability of aramid fibers. All these indicate that the addition of GNP further improves the performance of aramid insulation paper, improves the thermal stability of aramid insulation paper and delays the aging process of oil-immersed aramid insulation paper. This article provides a reference and basis for the preparation of meta-aramid insulation paper with relatively good thermal stability. [ABSTRACT FROM AUTHOR]

Nanostructured MnO2 with different morphologies based on carbon fiber paper (CFP) had been successfully synthesized via a hydrothermal process. The emphasis of this report focuses on the effect of the Co doping content on the morphologies and electrochemical properties of as-obtained MnO2 electrodes, thereby obtaining the optimal electrode material. Such optimal hierarchical porous nanoflowers entwined with nanowires architecture (Co-MnO2/CFP-1) was obtained by a certain Co content, which displayed an excellent capacitive performance. The Co-MnO2/CFP-1 electrode achieved a relatively high specific capacitance of 161 F g−1 at 1 A g−1, and 57% of the capacitance retention for Co-MnO2/CFP-1 when the current density ranging from 1 to 8 A g−1, which was 27 times than MnO2 without Co doping (MnO2/CFP), proving its excellent rate capability. The Co-MnO2/CFP-1 electrode exhibited a prominent cycle stability of 98% in 10,000 cycles at 4 A g−1. This significant improvement of capacitive performance benefits result from a well-developed interconnected hierarchical structure and provides more electrochemical active site, facilitating the penetration and diffusion of electrolyte. This study provides a general guidance to develop different morphologies of electrode materials for supercapacitor device. [ABSTRACT FROM AUTHOR]

[Display omitted] • Red beetroot is used as the only synthetic precursor for preparing carbon dots. • N-CDs serve as a ratiometric probe for DXR with LOD of 78.3 nM. • The ratiometric sensing of DXR is based on the occurrence of FRET. • 3D μPAD is applied for real-time visual monitoring DXR with the LOD of 130.9 nM. It is of great significance to develop fluorescence sensors that are both high-performance and environmentally friendly for on-site monitoring of doxorubicin (DXR), which plays a crucial role in protecting the ecological environment and human health. In this work, a rapid and ultrasensitive fluorescence sensing strategy based on red beetroot-derived carbon dots (N-CDs) is proposed for the determination of DXR. N-CDs are successfully prepared through facile hydrothermal treatment using red beetroot as the sole raw material, which have a cyan emission at 496 nm under the 416 nm excitation. Further, the proposed N-CDs serve as a sensitive fluorescent probe for the ratiometric determination of DXR owing to the occurrence of fluorescence resonance energy transfer effect (FRET). The detection limit (LOD) of DXR is calculated as 78.3 nM within the good linear range of 3-35 μM. Simultaneously, to achieve precise on-site analysis, a real-time fluorescent assay platform is proposed, which combines the portability of 3D microfluidics paper-based analytical device (3D-µPAD) with the analysis capability of smartphone. This platform enables the real-time monitoring of DXR in real samples with acceptable recoveries (98.9 %-103.2 %), presenting the promising application for CDs in on-site detection and drug safety supervision. [ABSTRACT FROM AUTHOR]

Carbon dots have been widely noticed due to their excellent optical properties, such as good photostability and a wide excitation wavelength range. However, the emission peaks of most known carbon dots (CDs) are in the blue region, which hinders their extensive applications in long‐wavelength emission. In this study, red‐emitting carbon dots (RCDs) that are pH‐responsive are synthesized using citric acid and urea as precursors, and their fluorescence intensity increased gradually with increasing solution pH from 1 to 12. A new mechanism based on H aggregation and Fermi energy level transfer is proposed to explain the pH‐responsive emission of RCDs. In contrast to the narrow response range of most pH‐sensitive CDs reported so far, the pH‐responsive range of RCDs is large, especially in the alkaline range, and their pronounced red light emission is well visualized. The prepared carbon dots have the advantages of non‐toxicity, low cost, and a wide pH response range. In addition, "rose" test paper and carbon dot PVA composite film, RCDs‐PVA film, are made to demonstrate the visualization of carbon dots in pH detection. The "rose" test paper and carbon dot PVA still have good fluorescence intensity. The prepared carbon dots have good application prospects for pH detection. [ABSTRACT FROM AUTHOR]

Scheme 1 The illustration of the synthesis of dual-emission type N, Cl-doped carbon dots by a simple hydrothermal route and the implications. [Display omitted] • Dual-emission N, Cl-CDs with strong orange fluorescence were simply synthesized. • The N, Cl-CDs exhibited precise sensing toward VB 2 , VB 9 , VB 12 in aqueous solution. • Visually semiquantitative detection of three VBs were performed on test strip. • The detection of VBs were successfully applied in real samples. Although a few of fluorescent probes based on carbon dots (CDs) for vitamin B (VB) determination have been emerged, none of them can realize the detection of different kinds of VB. In this paper, nitrogen, chlorine co-doped dual-emission CDs (N, Cl-CDs) with emissions at 404 nm and 595 nm have been easily synthesized. VB 2 , VB 9 and VB 12 can all induce obvious fluorescence turn-off response toward the N, Cl-CDs. Based on that, three types of VBs are quantitatively and sensitively evaluated in aqueous solution with wide concentration ranges of 14.9–135.0 μM, 34.7–89.8 μM and 29.8–79.8 μM, respectively. Importantly, visual semiquantitative detection of VBs on a test strip are also proposed. Moreover, the current N, Cl-CDs have been successfully applied to the detection of VBs in real samples. The N, Cl-CDs are sensitively multifunctional sensors for three kinds of VBs in aqueous solution and the visual semiquantitative detection by test paper assay is simple, portable and inexpensive. [ABSTRACT FROM AUTHOR]

The heteroatoms and transition metal co-doped carbon-based catalysts are an important way to improve the catalytic activity of oxygen reduction reaction (ORR). Herein, we reported a facile method to obtain iron, nitrogen, and sulfur co-doped cellulose paper carbon fibers as catalysts (Fe–N–S/CFs) for ORR in microbial fuel cells (MFCs) with the adsorption recovery of Congo red molecules from dye wastewater. The thermal treatment promoted the etching of carbon surface by ferric ions, resulting in increased surface roughness for forming the defective carbon structure. The rich active species and defective carbon formed on the etched surface to enhance the electroactive surface area and effective sites. Fe–N–S/CFs catalysts achieved high half-wave potential due to the synergy effect between chemical components and defect structures. The assembled single-chamber air cathode MFC gained a high maximum power density of 1773 ± 40 mW m−2 versus Pt/C MFC of 1325 ± 94 mW m−2. This work provides a strategy for recovering dye molecules from wastewater to prepare non-precious metal catalysts for enhancing ORR activity. • Mg(OH) 2 @PF was employed to efficiently adsorb Congo red from the dye wastewater. • Congo red/Mg(OH) 2 @PF co-calcined with iron nitrate to fabricate Fe–N–S/FCs catalyst. • The Fe–N–S/CFs showed the excellent ORR performance with the active specie of FeN x. • The assembled air cathode MFCs achieved high maximum power density (1773 ± 40 mW m−2). [ABSTRACT FROM AUTHOR]

Up-converting nanoparticles can be a demand for requirements in many areas, including bioimaging and conversion of energy, but also in the battle against counterfeiting. The properties of lanthanide ions make falsification difficult or even impossible using appropriately designed systems. The proposition of such an approach is the NaErF4:Tm3+@NaYF4 core@shell up-converting nanoparticles combined with transparent varnishes. Given the spectroscopic properties of Er3+ ions present in the fluoride matrix, the obtained up-converting nanoparticles absorb light by 808 and 975 nm wavelengths. The intentionally co-doped Tm3+ ions enable tuning characteristic green Er3+ emission to red luminescence, particularly desirable in anti-counterfeiting applications. The article includes a thorough analysis of structural and morphological properties. Moreover, this work shows that exclusive luminescent properties of NaErF4:Tm3+@NaYF4 NPs can be given to the transparent varnish, providing an excellent anti-counterfeiting system, revealing red emission under two different excitation wavelengths. [ABSTRACT FROM AUTHOR]

Synthesis of nitrogen and sulfur-doped graphene quantum dots via pyrolysis method using citric acid as a carbon source and L-cysteine as a sulfur and nitrogen source, for the detection of catechol and tryptophol on paper-based electrodes. [Display omitted] • N,S-GQDs is synthesized by pyrolysis in one step. • The detection of catechol and tryptophol is based on a paper-based ECL sensor using N,S-GQDs. • Establishing a Catechol Detection System in Wastewater. • Determination of the Quorum Sensing Molecule (Tryptophol) in Candida albicans. In this study, Nitrogen and Sulfur co-doped Graphene Quantum Dots (N, S-GQDs) were synthesized via a pyrolysis approach, utilizing citric acid as the carbon source and L-cysteine as the nitrogen and sulfur sources. These N, S-GQDs were used to develop a novel paper-based electrochemiluminescence (ECL) sensor for the detection of catechol (CC) and tryptophol, two potentially hazardous substances in the environment. Screen printing technology was utilized to construct the ECL sensor on filter paper, incorporating a hydrophobic layer, working and counter electrodes, and a reference electrode. The presence of CC and tryptophol was found to result in a decrease in the ECL intensity of the quantum dots (QDs), this quenching phenomenon is attributed to the oxidation of these substances within the electrochemical system and the subsequent electron transfer from the excited state of the QDs to the oxidation products. The sensor demonstrated a linear detection range for CC and tryptophol from 0.01 to 1000 μM, with detection limits of 0.0082 μM and 0.0066 μM, respectively, and exhibited excellent selectivity, stability, and repeatability. This cost-effective and efficient monitoring technique holds significant promise for environmental and health safety by facilitating the detection of CC and tryptophol, thereby mitigating their potential adverse impacts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyformamide-derived carbon nanowire arrays are in-situ synthesized as N-containing carbon coatings for cellulose-based carbon fibers. • The green H 2 O 2 solution acts as both dopant and activator. • The assembled solid-state symmetric supercapacitor yields encouraging capacitive properties. • This work paves a cost-effective and universal avenue toward structural and compositional engineering of electrodes in energy-related devices. Free-standing porous carbon have risen to prominent electrode materials for high-rate solid-state supercapacitors, yet they are still plagued by uneconomical petrochemical feedstocks, tedious slurry-casting processes, and suboptimal performance. Herein, a dual‐strategy of combining free-standing nitrogen-doped carbon nanowire array coating and pore engineering is designed to boost the performance of cellulose-derived carbon electrodes. Polyformamide-derived carbon nanowire arrays are in-situ synthesized as N-containing carbon coatings for cellulose-based carbon fibers. More intriguingly, H 2 O 2 activation further enhances the hierarchical porous structure. Benefiting from the synergistic effect of free-standing feature, high electrolyte compatibility, interconnected conductive fiber networks, well-developed hierarchical porous structure and stable heteroatom-doped carbon coatings, the designed electrodes possess high accessibility of electrolyte ions and effective ion/electron transport channels. Thus, the specific capacitance reaches 275.6 F g−1 at 0.5 A g−1 for aqueous supercapacitor. The solid-state symmetric supercapacitor demonstrates the specific capacitance of 126.5 F g−1 at 0.5 A g−1 with the capacitance retention of 64.5% even when the current densities increased by 40-folds. Their promising energy density (17.5 Wh kg−1) and power density (12.3 kW kg−1) closing to the state-of-the-art biomass-derived free-standing solid-state symmetric supercapacitors. This breakthrough symbolizes a step forward in the advancement of biomass as high‐performance electrodes for supercapacitors. [ABSTRACT FROM AUTHOR]

A well-designed support material between catalyst and substrate can always significantly enhance the performance of an electrode on water oxidation. In this work, a functional Ni and N-doped carbon layer (NNC) was designed on carbon paper (CP) via pyrolysis by using a controlled electrodeposited polyporphyrin as a precursor. Consequently, the fabricated NiFe-LDH/NNC/CP achieved a catalytic current density of 100 mA cm−2 at a small overpotential of 231 mV with a low Tafel slope of 26.0 mV dec−1, as well as high durability for more than 360 h. The insights are that N-doping reinforces the hydrophilicity and the catalyst binding capacity, while Ni-doping intensifies the conductivity. [ABSTRACT FROM AUTHOR]

Polypyrrole@cellulose fibers (PPy@CFs) electrode materials are promising candidates in the energy storage. Various strategies have been pursued to improve their electrochemical performance. However, the poor conductivity, specific capacitance, and cyclic stability still hindered its application. Compared with the previous studies, we selected AQS with electrochemical activity as a dopant to improve these defects. It exhibits a high capacitance of 829.8 F g−1 at a current density of 0.2 A g−1, which is much higher than that of PPy@CFs electrode material (261.9 F g−1). Moreover, the capacitance retention of PPy:AQS/p-PTSA@CFs reaches up to 96.01% after 1000 cycles, indicating superior cyclic stability. Therefore, this work provides an efficient strategy for constructing high-performance electrode materials for energy storage. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Aluminum-doped paper (AP)-based flexible heater chips are proposed. • The AP heater chips are used as a low-voltage thermal igniter for nanoscale energetic materials (nEMs). • Fully integrated compact systems with remote and selective ignition (RSI) capabilities for nEMs are developed. • The RSI systems are demonstrated to ignite nEMs wirelessly and selectively with a smartphone. Abstract Development of low-voltage driven multifunctional thermal igniters for nanoscale energetic materials (nEMs) is important for extending the application of nEMs to various thermal engineering fields. In this study, highly flexible heater chips capable of generating a sufficient amount of heat to ignite nEMs at a low voltage are demonstrated by incorporating a patterned aluminum-doped paper (AP) with polymeric substrates. A combination of automatic paper cutting and single-step ultraviolet polymer curing techniques helps in the fabrication of various designs of flexible AP heater chips in a simple and low-cost manner. Based on the AP heater chips, three models of flexible thermal igniters are designed to develop new functions such as selective ignition and sequential ignition in a single chip and successfully operated at low voltages. Two types of compact ignition systems are fabricated by fully integrating the arrayed AP igniters, circuit modules, and portable batteries in a three-dimensional printed single package and on a flexible circuit board. The systems are successfully demonstrated to ignite nEMs wirelessly and selectively with a smartphone. [ABSTRACT FROM AUTHOR]

My comments concern the errors in the crystallographic part of the commented paper. The diffraction patterns are erroneously analysed. The crystal structure was not presented in the commented paper. • Correction of erroneous analysis of diffraction patterns. • Comparison of unit cells relation to the content of Ca dopant. • The crystal structure was not given in the commented paper. [ABSTRACT FROM AUTHOR]

Time-resolved multicolor dynamic anti-counterfeiting was achieved by exploiting the stimuli-response properties and lifetimes differences between NOCQDs and NCQDs, realizing the 5D information encryption in all five stimulus-, pattern-, time-, and color-dependent codes. [Display omitted] • Through precise regulation, two kinds of carbon quantum dots (CQDs) were prepared. • The color of afterglow is dependent on excitation wavelength. • Information encryption and dynamic identification were realized in 5D mode. Multi-stimuli responsive multicolored room-temperature phosphorescent (RTP) carbon quantum dots (CQDs) have recently attracted considerable attention, owing to their potential applications in advanced dynamic anti-counterfeiting. The design and development of carbon dots that exhibit both stimulus response characteristics and multicolor RTP emission remains a significant challenge in the field. In this work, we present a novel approach to control the dynamic phosphorescence color and stimulus response properties of CQDs coated on paper by fine-tuning the surface functional groups of the CQDs. Specifically, histidine and 2,4,6-triaminopyrimidine was separately used to prepare N, O co-doped CQDs (NOCQDs) and N-doped CQDs (NCQDs), respectively. These CQDs were further coated on filter paper substrates to achieve water and heating cascade stimulus–response RTP. These stimuli-responsive properties of NOCQDs can be modulated by deprotonating their surface oxygen-containing groups. Eventually, we achieved time-resolved multicolor dynamic anti-counterfeiting by exploiting the stimuli-response properties and lifetimes differences between NOCQDs and NCQDs, realizing the 5D information encryption in all five stimulus-, pattern-, time-, and color-dependent codes. These findings highlight the potential of NOCQDs as advanced anti-counterfeiting materials and lay a foundation for further exploration into the synthesis and properties of CQDs with tunable stimuli-response features and RTP emission. [ABSTRACT FROM AUTHOR]

This response mainly deals with the scientific description of the comments on the structure of the published compound (Bi 1/2 K 1/2)(Fe 1/2 W 1/2)O 3. The newly designed (Bi 1/2 K 1/2)(Fe 1/2 W 1/2)O 3 compound was prepared using the solid-state reaction method. The ingredients were taken to satisfy the required stoichiometry/chemical composition to form a single-phase compound. The lattice parameters and structure is strongly affected by K and W doped elements. The structural analysis is supported by the results of other experimental techniques (dielectric study, Raman characterization, Hysteresis loop, etc.). [ABSTRACT FROM AUTHOR]

With the improvement of operation requirements of power equipment, the stable operation of insulation of equipment is very important. Among them, insulating paper is one of the main factors affecting the state of equipment. Therefore, it is important to improve the performance of insulating paper. The pure cellulose model and h‐BN/cellulose composite model are established to analyze the improvement of thermal and mechanical properties of insulating paper cellulose. The effects of different contents of h‐BN doping on the properties of cellulose are studied by comparing the mechanical parameters, cohesive energy density, thermal conductivity, mean square displacement, and free volume of cellulose before and after h‐BN doping through molecular dynamics method. The results indicate that the thermal conductivity and thermal stability of cellulose are improved by more than 15% at the h‐BN mass fraction of 2% and 3%, the shear modulus and elastic modulus are enhanced by more than 50%, and the deformation resistance and ductility of the composites are enhanced when the mass fraction of h‐BN is 2%. The doping of h‐BN has an important impact on improving the thermodynamic properties of cellulose, which is of great significance to improving the insulation performance of power equipment and reducing equipment faults. [ABSTRACT FROM AUTHOR]

[Display omitted] • N-doped 1T-2H MoSe 2 /N doped carbon paper was fabricated by a low-temperature nitrogen plasma strategy. • N doping along with 1T phase into the 2H-MoSe 2 can expose more active edge sites and improve electrical conductivity. • N-MoSe 2 /NCP-30 only needs an overpotential of 274 mV to reach −200 mA cm−2 with Tafel slope of 54.7 mV dec-1. Molybdenum selenide (MoSe 2) is considered to be a promising catalyst for seawater hydrogen evolution, but its catalytic activity falls far short of requirements due to its inert surface. Here, self-supported N-doped 1T@2H-MoSe 2 /N doped carbon paper (N-MoSe 2 /NCP) was fabricated by a novel low-temperature nitrogen plasma strategy. In alkaline simulated seawater, the optimized N-MoSe 2 /NCP-30 only requires an overpotential of 274 mV to reach −200 mA cm−2 with Tafel slope of 54.7 mV dec-1, and exhibits stability over 24 h. This work proposes that the introduction of 1 T phase and N dopant into 2H-MoSe 2 using low-temperature plasma strategy can significantly facilitate the exposure of abundant active edge sites and boost the conductivity of MoSe 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • The dual-emission ratiometric fluorescent probe was prepared by a facile hydrothermal synthesis method. • The quantification of Pb2+ was based on the efficient FRET between NCDs and AuNCs. • The sensor has good selectivity and anti-interference ability with satisfactory recovery in real water samples. • A paper-based sensor was fabricated for visual semi-quantitative detection by color change. Ratiometric fluorescent sensors could effectively eliminate the interference of spontaneous fluorescence or instrument fluctuation to improve the analysis sensitivity and accuracy. In this work, a dual-emission nitrogen-doped carbon dots/AuNCs (NCDs-AuNCs) nanohybrid was fabricated under mild conditions by the hydrothermal method, without additional coupling agents, which is facile and environmentally friendly. The prepared nanohybrid was employed for the sensitive detection of Pb2+. The sensor exhibited dual emission peaks at 460 and 625 nm with efficient fluorescence resonance energy transfer under a single excitation wavelength of 360 nm, in which the red fluorescence of AuNCs was enhanced and the blue fluorescence of NCDs was slightly quenched with the presence of Pb2+. The quantitative analysis of Pb2+ was performed upon the change of both fluorescence intensities. The sensor was successfully used for Pb2+ detection in real water samples with satisfactory spiking recoveries in a range of 91.0%–101.3% and low relatively standard deviations (RSDs < 3%), which exhibited good selectivity and anti-interference ability. In addition, a paper-based sensor was fabricated by immobilizing the nanohybrids on filter paper, which enables the visual semi-quantitative determination of Pb2+ by the naked eye through the color transition from blue to pink. The prepared NCDs-AuNCs nanohybrids showed great application potential in environmental water monitoring in an efficient and green way. [ABSTRACT FROM AUTHOR]

[Display omitted] • Paper-based cascade sensitized structure of CuInSe 2 /Cu 3 (BTC) 2 /Y:ZnO was assembled. • The entropy-driven SDA propelled DNAzyme roller amplification strategy was designed. • Surface plasmon resonance-enhanced cascaded sensitization effect was proposed. Herein, the surface plasmon resonance (SPR)-enhanced cascaded sensitization effect of CuInSe 2 /Cu 3 (BTC) 2 /yttrium doped ZnO (Y:ZnO) photosensitive structures were integrated on lab-on-paper photoelectrochemical (PEC) biosensing platform for the ultrasensitive detection of microRNA-21 (miRNA-21) based on entropy-driven strand displacement amplification (SDA) propelled DNAzyme roller amplification strategy. The Y element doping equipped the paper-based Y:ZnO nanorods with enhanced PEC performance, which was further cosensitized with Cu 3 (BTC) 2 metal-organic framework (MOF) and CuInSe 2 quantum dots (QDs), giving a cascaded sensitization effect for generating a robust and stable photocurrent signal. The SPR effect between CuInSe 2 QDs and Au nanoparticles (NPs) was activated with the aid of entropy-driven SDA propelled DNAzyme roller amplification-induced conversion of target miRNA-21 to Au NPs-labelled track DNA (track DNA-Au), which could effectively promote the photogenerated carrier separation and transfer of CuInSe 2 /Cu 3 (BTC) 2 /Y:ZnO cascade sensitized structures via hot-electron transfer mechanism, further enhancing the photocurrent signal. Based on this designed "signal-on" mode, the quantitative detection of miRNA-21 was achieved with high sensitivity, good specificity, and excellent practicability, which provided a promising model for developing lab-on-paper diagnostic tool for biomedicine. [ABSTRACT FROM AUTHOR]

Epoxy resin-impregnated insulating paper (RIP) is the main insulation of the high-voltage direct-current (HVDC) dry bushing. In order to solve the problem of uneven radial electric field distribution of the bushing, the insulating paper was modified by nano-SiC with filling concentrations of 0-7wt% and impregnated with pure epoxy resin. The dispersibility of nanoparticles was observed by scanning electron microscope. Their conductivity, dielectric, and breakdown properties were tested. The results showed that the electrical conductivity of RIP could be improved by filling it with nano-SiC, and nano-SiC/RIP had obvious nonlinear conductivity characteristics. Comsol-Multiphysics was used to simulate the electric field of the HVDC dry bushing with 0-7wt% nano-SiC/RIP as the main insulation. The simulation results showed that the radial electric field uniformity decreased from 3.04 to 1.20 when concentrations increased from 0 wt% to 7 wt%. Finally, considering the comprehensive factor, 5wt% was considered the optimal doping concentration. [ABSTRACT FROM AUTHOR]

The active mass of the plates of aspent car battery with higher wear after an efficient desulfatization can be used as sources of a new electrode. This paper proposes the recycling of spent electrodes from a lead acid battery and the incorporation of NiO or Co3O4 contents by the melt-quenching method in order to enrich the electrochemical properties. The analysis of X-ray diffractograms indicates the gradual decrease in the sulfated crystalline phases, respectively, 4PbO·PbSO4 and PbO·PbSO4 phases, until their disappearance for higher dopant concentrations. Infrared (IR) spectra show a decreasing trend in the intensity of the bands corresponding to the sulfate ions and a conversion of [PbO3] pyramidal units into [PbO4] tetrahedral units by doping with high dopant levels, yielding to the apparition of the PbO2 crystalline phase. The observed electron paramagnetic resonance (EPR) spectra confirm three signals located on the gyromagnetic factor, g~2, 2.2 and 8 assigned to the nickel ions in higher oxidation states as well as the metallic nickel nanoparticles. This compositional evolution can be explained by considering a process of the drastic reduction in nickel ions from the superior oxidation states to metallic nickel. The linewidth and the intensity of the resonance lines situated at about g~2, 2.17, 4.22 and 7.8 are attributed to the Co+2 ions from the EPR data. The best reversibility of the cyclic voltammograms was highlighted for the samples with x = 10 mol% of NiO and 15 mol% of Co3O4, which are recommended as suitable in applications as new electrodes for the lead acid battery. [ABSTRACT FROM AUTHOR]

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The development of noble-metal-free electrocatalysts with high electrocatalytic performance and stability by adopting a scalable route is key to solving the energy crisis. We report a P Ni co-doped Mo 2 C-based electrocatalyst with high hydrogen evolution reaction (HER) catalytic activity prepared by a molten-salt method. Using phosphating times of 2 h and 4 h yielded P-Ni-Mo 2 C-2h and P-Ni-Mo 2 C-4h, respectively, both of which exhibited nanoflower-like structures that provided abundant active sites for the reaction. P-Ni-Mo 2 C-2h possessed good electrocatalytic properties with a low overpotential of only 140.5 mV at j = 10 mA cm−2 and a small Tafel slope of 50.7 mV dec−1 in an alkaline environment. P-Ni-Mo 2 C-2h exhibited excellent stability after 20 h of continuous hydrogen production. The use of an excessively long phosphating time caused a narrow down of spaces formed by nanoflakes, thereby reducing the HER performance of the electrocatalyst. The results of this study provide guidelines for the preparation of high-efficiency P Ni co-doped electrocatalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

This work reports a modification of a fibrous cellulose material (paper) by the addition of polyacrylonitrile (PAN) fibres doped with 10,12–pentacosadiynoic acid (PDA). The fibres are sensitive to ultraviolet (UV) light. When the paper containing PAN–PDA is irradiated with UV light it changes colour to blue as a consequence of interaction of the light with PDA. The colour intensity is related to the absorbed dose, content of PAN–PDA fibres in the paper and the wavelength of UV radiation. The features of the paper are summarised after reflectance spectrophotometry and scanning microscopy analyses. All the properties of the modified paper were tested in accordance with adequate ISO standards. Moreover, a unique method for assessing the unevenness of the paper surface and the quality of printing was proposed by using a Python script (RGBreader) for the analysis of RGB colour channels. The modification applied to the paper can serve as a paper security system. The modified paper can act also as a UV radiation indicator. [ABSTRACT FROM AUTHOR]

A facile approach for producing fluorescent composite paper containing nitrogen-doped graphene quantum dots (N-GQDs) and graphene on the surface of the modified fibers was implemented from the exfoliation of graphite oxide (GO) using a one-step hydrothermal method. The properties of the composite paper were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV), photoluminescence spectroscopy (PL), and confocal laser scanning microscopy (CLSM). The results indicated that the GO was reduced to graphene sheets, and the N-GQDs nanoparticles were deposited on the surface of these sheets. The composite paper remained undamaged, with a three-dimensional structure and smooth fibers during the hydrothermal process, and the average particle size of N-GQDs was less than 10 nm. Photoluminescence measurements showed that the composite paper had a strong ultraviolet absorption in the range of 200 to 340 nm, and the band edge emission occurred at 475 nm. The CLSM image of composite paper exhibited a well-defined excitonic emission feature with an excitation wavelength of 405 nm. [ABSTRACT FROM AUTHOR]

Pt-based bimetallic alloys have attracted intensive interests as highly efficient and stable heterogeneous catalysts for fuel cell applications, and searching flexible free-standing nanomembranes has been on the research focus because of their promising applications in catalysis, nanoelectronics, batteries, and sensing. Herein, a flexible free-standing paper composed of FePt alloy nanoparticles on nitrogen-doped paper (FePt-NG paper) has been developed as integrated electrode towards electrocatalytic oxidation of formic acid. It is found that, N doping is beneficial for the well dispersion of FePt nanoparticles on NG paper. The synergistic effect between Fe and Pt, as well as N doping effect simultaneously assures the improved catalytic activity of FePt-NG paper, making it the promising flexible electrode for application in fuel cell system. Moreover, the synthesis strategy could be used for the construction of other free-standing electrode towards catalysis, sensing, and battery applications. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Free-standing graphene composite papers exhibit very high flexibility and stability. Therefore, these materials are preferred as modular electrodes for some electrochemical applications, e.g. electrochemical sensors, supercapacitors, and batteries. Graphene composite papers are usually doped with different substances to improve their electrical conductivity, electrochemical performance, and stability. This work describes the fabrication of flexible and free-standing reduced graphene oxide (rGO) papers doped with phenazine, phenothiazine, phenoxazine, xanthene, acridine, and thiazole class of dye molecules. Fabrication procedure was applied by two basic steps: vacuum filtration of a dispersion containing GO sheets and dye molecule through a membrane and reduction of free-standing GO/dye paper to rGO/dye paper by treatment with hydriodic acid. Characterization of these rGO/dye papers were achieved by using scanning electron microscopy, scanning tunneling microscopy, energy dispersive X-ray analysis, powder X-ray diffraction spectroscopy, Raman spectroscopy, fourier transform infrared spectroscopy, UV–vis. absorption spectroscopy, four-point probe conductivity measurement and cyclic voltammetry techniques. Electrical conductivity and electrochemical performance studies indicated that acriflavine (Acr) doped rGO paper electrode exhibited the best performance for electrocatalytical oxidation of nitrite. When rGO/dye paper was applied as amperometric sensor for nitrite, the sensor was very stable, flexible, and reproducible. rGO/Acr paper demonstrated good quality parameters with sensitivity of 0.40 μAμM −1 cm −2 , detection limit of 0.12 μM, and linear range of 0.40–3600 μM. [ABSTRACT FROM AUTHOR]

In this work, we provide a novel strategy to improve the charge balance in organic light emitting devices (OLEDs) by optimizing the hole injection layer (HIL) and thereby controlling the overall hole supply in the device. The lowest unoccupied molecular orbit (LUMO) of the p‐dopant proposed in this work, PD02, is ‐4.63 eV, much shallower than that of the commercial material (PD01). Nevertheless, this enables use of the doping concentration to modulate the supply of holes to the emissive layer to control the charge balance. We demonstrate that device performances are significantly improved by employing such a scheme. With 23% molar doping of PD02, a bottom emission red OLED achieves external quantum efficiency (EQE) over 30%, operating voltage of 3.4 V and LT95 ~ 15,000 h at 10 mA/cm2. Moreover, the efficiency roll‐off is also suppressed up till ~ 3,500 cd/m2, a desirable feature in display applications. A study of exciton distribution within the emissive layer suggests that improved charge balance is indeed achieved in the optimized structure. An additional benefit from the modified HIL is its lower lateral conductivity relative to the standard formula, which reduces crosstalk between RGB pixels. [ABSTRACT FROM AUTHOR]

In this work, a facial ratiometric fluorescence nanorpobe (RFP) based on gadolinium and nitrogen co-doped CDs (Gd , N -CDs) was for the first time proposed for visual detection of folic acid (FA). The Gd , N -CDs were prepared by hydrothermal heating of Gd(NO 3) 3 ⋅6H 2 O, o-phenylenediamine (OPD), 4-aminobenzoic acid (PABA). The as-prepared Gd , N -CDs had an average particle size of 10.27 ± 0.35 nm and exhibited two emission bands at 396 and 548 nm, respectively upon excitation at 340 nm. In the presence of FA, the 560 nm emission of Gd , N -CDs was reduced while the fluorescence signal at 457 nm was enhanced, and the quantitatively determination of FA was based on the fluorescence intensity ratio (F 457 /F 560). The as-constructed RFP achieved a linear range of 0.0–30.0 μM and a low detection limit (LOD) of 3.43 nM. In particular, a distinguishable change in fluorescence colour from bright orange to blue enabled the development of a smartphone-assisted visual sensing platform and a paper-based analytical device for FA detection with LODs of 3.06 μM and 0.83 μM, respectively. The proposed sensing platform was successfully utilised for onsite detection of FA in vegetable, fruit and yolk samples with satisfactory results were achieved. This work highlights the application potential of smartphone-integrated CDs-based RFP as a promising portable method for on-site analysis of FA. [Display omitted] • A Gd , N -CDs-based ratiometric fluorescence method was proposed for ultrasensitive sensing of folic acid. • The proposed method realized folic acid visualization by integrating with a smartphone and a paper device. • The proposed fluorescence methods were successfully used for folic acid detection in food samples. [ABSTRACT FROM AUTHOR]

A low-cost and efficient MoS 2 /graphite paper (GP) counter electrode for dye-sensitized solar cells (DSSCs) is first fabricated by a simple and effective solution processed route. Photo-electric conversion efficiency of 6.48% is obtained for the DSSC adopting MoS 2 /GP, better than the device (6.22%) employing platinized F-doped tin oxide (Pt/FTO) electrode. Because highly conductive GP is performed as a substrate, and the mechanical adhesion and electrical connection between the MoS 2 film and the GP substrate are strong, the series resistance of MoS 2 /GP is much smaller than that of Pt/FTO. A comparable charge transfer resistance of MoS 2 /GP to Pt/FTO is found to be another factor for the better performance. Due to the MoS 2 prepared here possessing relatively high crystallinity and firmly being anchored on the GP substrate, MoS 2 /GP as well exhibits high stability. Hence, excellent electrochemical activity, high stability, facile preparation and low material cost of the MoS 2 /GP electrode offer it a promising potential for large-scale production. [ABSTRACT FROM AUTHOR]

Based on the fluorescence quenching principle, a novel lanthanum-doped carbon quantum dots (La-CQDs) fluorescence probe was successfully developed for ion detection of Fe3+. La-CQDs with a fluorescence quantum yield of 29.93% was prepared in ethanol solution using ammonium citrate as the carbon source and lanthanum nitrate as the dopant. The luminescence performance of La-CQDs was enhanced by La doping and maintained over 90% of the maximum fluorescence intensity in different anions, water content and organic solvent environments. In the range of 25–200 μM, the fluorescence intensity of La-CQDs displayed a good linear relationship (Y = 0.00675X+ 1.07679, R 2 = 0.9888) with the concentration of Fe3+ and its limit of detection (LOD) was calculated to be 6.78 μM. The method was successfully applied to the detection of Fe3+ in green tea and the measurement error was less than 3%. In addition, La-CQDs was developed for fluorescent colorimetric test paper and information anti-counterfeiting, while the fluorescence quenching effect was observed intuitively on the paper. Lanthanum-doped carbon quantum dots (La-CQDs) prepared by one-step solvothermal method for Fe3+ detection, fluorescent colorimetric test paper and information anti-counterfeiting. [Display omitted] • A novel lanthanum-doped carbon quantum dots (La-CQDs) was synthesized by a one-step solvothermal method. • The synthesized La-CQDs emitted distinct blue fluorescence with a quantum yield of 29.93%. • A fluorescent colorimetric test paper using La-CQDs for the detection of Fe3+. • Exploring the fluorescence quenching mechanism of La-CQDs using fluorescence information anti-counterfeiting. [ABSTRACT FROM AUTHOR]

We propose here a quick and easy procedure for preparing pencil leads doped with Ag and AgCl suitable for the reproducible and easy drawing on paper or other porous supports of carbon based Ag/AgCl conductive lines for the use as reference electrodes. They were prepared by careful electrodeposition of silver and silver chloride on carbon powder (conductive material) which was then mixed with sodium bentonite (binding agent) and sodium silicate (hardening agent). Extrusion at room temperature of these mixtures from a suitable die allowed thin rods to be obtained, which were then inserted in commercial lead holders to facilitate their use for drawing electrodes on paper. Their performance was evaluated by voltammetric measurements conducted by using hexacyanoferrate(II) and 1,2-hydroxybenzene as probe species known to display a reversible electrochemical behaviour. The results found pointed out that the potential exhibited by these drawn reference electrodes was fully reliable only when small but controlled amounts of chloride ions can be added to assayed samples, without interfering investigated processes. Conversely, a poorer reliability characterise these reference electrodes when chlorides cannot be added, in that they display potentials higher of about 100–150 mV than their theoretical value. Their reproducibility (± 0.02 V), controlled on a series of different PEDs wetted with the same sample, was however so narrow for voltammetric investigations as to make their use preferable to usual pseudo-reference electrodes whose potential is remarkably affected by the different components present in assayed samples. [ABSTRACT FROM AUTHOR]

The rapid growth of environment pressures and fast depletion of fossil fuels compel public to pay more attention on developing affordable and efficient catalysts for renewable energy production. Metal (Co, Fe, Ni, etc.) phosphide nanoparticles uniformly encapsulated in porous N,P-codoped nanofibrous carbon coated on carbon paper (MeP@NPC/CP) are prepared through one-pot carbonization-phosphorization strategy, which are potential for effective electrocatalytic water reduction/oxidation reactions. The well-designed self-supported structure and the abundant accessible active centers together contribute to the high electrocatalytic performance for hydrogen and oxygen evolution. Remarkably, an alkaline electrolyzer assembled from CoP@NPC/CP as cathode and anode can afford the current density of 10 mA cm −2 at the voltage of 1.67 V for overall water splitting in alkaline media with excellent stability. The easily prepared route with suitable structural and textural properties endows this self-supported materials with versatile function as abundant metal catalysts for realistic energy conversion and storage systems. [ABSTRACT FROM AUTHOR]

Highlights: [•] Solution coating of metal oxide layer directly onto carbon paper. [•] Most uniform Metal oxide coating on functionalized carbon paper. [•] Highest electrochemical stability for metal oxide coated functionalized carbon paper. [ABSTRACT FROM AUTHOR]