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A hierarchically porous nitrogen, oxygen-rich carbon material is developed by Mg(NO 3) 2 treatment of filter paper in a one-step pyrolysis. The obtained carbons exhibit high specific surface area (1031 m2 g−1), interconnected micro-, meso-, and macroporous conductive network and attractive heteroatom contents (2.84 at.% nitrogen and 13.82 at.% oxygen). The as-prepared carbon tested as anode for lithium ion batteries displays an excellent reversible capacity (1560 mAh g−1 at 0.1 A g−1), superior rate capability (501 mAh g−1 at 5 A g−1) and desired cycling performance (1538 mAh g−1 at 0.1 A g−1 and 1105 mAh g−1 at 1 A g−1after 100 cycles). Moreover, a full battery with an as-obtained carbon anode and a LiFePO 4 cathode delivers a high discharge capacity of 165 mAh g−1 (the theoretical capacity of LiFePO 4 was 170 mAh g−1) and good cyclability (156 mAh g−1 after 20 cycles). Unlabelled Image • A hierarchically porous nitrogen, oxygen-rich carbon was fabricated in a one-step pyrolysis. • The as-obtained carbon delivers superior electrochemical performances for LIBs. • Mg(NO 3) 2 can not only acts as a pore-making agent, but also contributes to the heteroatom doping effects. [ABSTRACT FROM AUTHOR]

Abstract Black liquor, an industrial waste, also generally called spent liquor is a promising feedstock for production of bio-carbon due to its high lignin and energy contents. Mild processing conditions and sustainable resource utilization can drive commercial utilization of this industrial waste. A novel oxidative procedure using hydrogen peroxide as a green liquid oxidant at room temperature for processing of paper recycling neutral sulphite semi-chemical spent liquor was established and evaluations were carried out for its efficiency. Standard hydrothermal carbonization was carried out for comparing bio-carbon production qualitatively and quantitatively using the same spent liquor. The oxidation procedure was performed at room temperature using 5% of H 2 O 2 followed by washing in diluted sulfuric acid (0.15 N) while hydrothermal carbonization was performed at 250 °C. The bio-carbon produced were similar in terms of ash percentage and ranged from 1.25 ± 0.05 to 1.48 ± 0.05% for oxidation method and from 1.11 ± 0.03 to 1.45 ± 0.04% for hydrothermal carbonization. The carbon contents for the oxidation method ranged from 60.54 to 61.50% and 66.81–67.31% for hydrothermal carbonization while higher heating values ranged from 25.32 to 26.11 MJ/kg and from 28.68 to 29.34 MJ/kg respectively. The mass yield ranged from 29.98 to 31.88% by the oxidation, while it was 15.02–16.08% by hydrothermal carbonization. Highlights • Bio-carbon is generated from byproduct of plant that uses recycled paper feedstock. • Oxidation method is a promising approach to obtain pure bio-carbon from spent liquor. • Hydrothermal carbonization demands energy for pure bio-carbon production. • Bio-carbon from both methods differ quantitatively but are similar qualitatively. • Bio-carbon can be a potential platform for environmental friendly fuel and materials. [ABSTRACT FROM AUTHOR]

Developing efficient and cheap electrocatalysts as substitutes for commercial Pt/C in the oxygen reduction reaction(ORR)is extremely necessary. Herein, paper mill sludge (PMS) was utilized to produce iron, nitrogen and sulfur co-doped carbon nanotube/nanoporous carbon nanocomposite (PMS-CNT/C) by pyrolysis. PMS-CNT/C-b, one of as-prepared PMS-CNT/C exhibited excellent oxygen reduction reaction activity with an onset potential of 0.99 V vs. RHE and half-wave potential of 0.77 V vs. RHE, which was similar to the commercial Pt/C catalyst (onset potential of 0.99 V vs. RHE and half-wave potential of 0.76 V vs. RHE). It had longer-term stability and higher methanol tolerance in alkaline medium than Pt/C. Moreover, the new catalyst also exhibited excellent catalytic performance in neutral solution. The energy output of microbial fuel cells loaded with PMS-CNT/C-b catalyst was also higher than that of commercial Pt/C under neutral condition. The excellent ORR performance of PMS-CNT/C-b was due to the carbon nanotube/nanoporous structure and the synergistic effect of abundant N groups, iron nitrides and thiophene-S. The formation of CNTs in the carbon nanotube/nanoporous carbon nanocomposite was mainly attributed to melamine, which was added into PMS and was at first just considered as a nitrogen source to develop N-doped PMS-based catalysis in this work. The synthesis of paper mill sludge-based carbon nanotube/nanoporous nanocomposite and its excellent ORR activity will make the new catalyst a promising cathodic electrocatalyst alternative for fuel cells. • Paper mill sludge (PMS) was utilized to fabricate Fe, N and S co-doped carbon materials. • Melamine was directly added into PMS to assist the formation of CNTs. • The PMS-based nanocomposites exhibited excellent catalytic activity for ORR. • A green and efficient strategy was developed for the reuse of PMS. [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]

Abstract Paper cup composed of crude cellulose is a common waste in daily life. In this paper, hierarchical porous carbons have been successfully prepared by an initial hydrothermal treatment and subsequent activation route from abandoned paper cup, and then paper cup derived carbons are used as scaffolds to fabricate serial carbon/Se composites. The optimal composite presents unique 3D porous structure, with amorphous selenium uniformly confined into the micropores of carbon. As the cathode materials of Li-Se battery, this composite reveals an initial reversible discharge capacity of 517.2 mAh g−1 at 0.2C, and a capacity value of 431.9 mAh g−1 can be retained after 60 cycles. Even at a high rate of 4C, a capacity value of 295.8 mAh g−1 can be obtained. By comparison, the improved electrochemical performance of the optimal composite should be attributed to reasonable porous structure and effective encapsulation of amorphous selenium. Graphical abstract Image 1 Highlights • Synthesis of porous carbon/Se composite from abandoned paper cup. • Porous carbon/Se composite delivers a stable discharge capacity of 295.8 mAh/g at 4C. • The structure-function of different carbon/Se composites is studied. [ABSTRACT FROM AUTHOR]

The security of food and drink water is of great concern in our daily life, because the threat from heavy metals pollution in environment is extensively existed. Carbon dots (CDs) is promising for a wide range of applications because of its excellent chemical and optical properties. Herein, yellow emissive carbon dots (YCDs) were constructed by a facile mild condition. The YCDs emitted bright emission at 562 nm with excitation of 420 nm and the quantum yield of 17.44%. The fluorescence of YCDs can be utilized of sensing Hg2+ with limit of 16.8 nM. The mechanism of detection for Hg2+ can be attributed to static quenching effect (SQE) and dynamic quenching effect (DQE) process. A fluorescent portable paper detection platform based on YCDs integrated with a smartphone APP were developed for real-time and rapid analysis of Hg2+ with limit of 0.11 μM. Notably, YCDs were successfully employed to the detection of Hg2+ in various food and real water with recoveries of 97.50 ± 2.63% – 108.64 ± 0.15%, indicated satisfied sensing performance and excellent environmental tolerance. The fluorescence sensing system based on YCDs provided a reference for the construction of portable sensors for hazardous substance monitoring. [Display omitted] • Controllable synthesis of yellow emissive carbon dots by mild heating process. • A visual testing platform based on paper sensor was developed for Hg2+ on-site assay. • High selectivity and sensitivity with rapid response achieved by smartphone APP. • Real sample analysis for Hg2+ detection with satisfied results. [ABSTRACT FROM AUTHOR]

[Display omitted] • Filter paper is used as carbon source to prepare highly porous N-doped carbon. • KHCO 3 is chosen as the activator because it is safe and non-corrosive. • Addition of urea at the activation step significantly improves the surface area. • At 0 °C and 20 bar, the carbon shows high CO 2 uptake of 19.65 mmol/g. Herein, we presented the preparation of N-doped porous carbon from lab used filter paper. Filter paper was first carbonized at 500 °C. The obtained carbon was then pyrolyzed with KHCO 3 and urea. Effects of KHCO 3 activation on the carbons' physicochemical properties were thoroughly investigated. The derived carbon materials were also tested for CO 2 adsorption with pressure up to 20 bar. The carbons exhibited very high CO 2 uptake of 19.65 mmol/g at 0 °C and 20 bar. The correlations between adsorption performances and the carbons' physicochemical properties at 1/20 bar were analyzed and discussed. [ABSTRACT FROM AUTHOR]

A filter-paper-derived nanofibrous silica–carbon composite composed of thin silica layer conformally coated on carbon nanofibers is synthesized by employing natural cellulose substance (ordinary laboratory filter paper) as both scaffold and carbon source. When the nanocomposite is employed as an anode material for lithium-ion batteries, it displays improved lithium-ion storage performance compared with the bare silica and carbon counter materials, due to the unique three-dimensional porous network structures of the carbon fiber scaffold and the thin silica layer. For the silica–carbon nanocomposite with 31.2 wt% of silica content and the silica layer with a thickness of ca. 60 nm, it delivers a stable discharge capacity of ca. 400 mAh g −1 after 200 discharge/charge cycles at a current density of 100 mA g −1 . Moreover, improved electrochemical performances are achieved by coverage of an additional carbon layer or deposition of silver nanoparticles onto the silica–carbon nanofibers, which exhibits specific capacities of 488.7 and 477.5 mAh g −1 after 100 discharge/charge cycles, respectively. The current synthetic method provides a facile and low-cost strategy for the large-scale production of nanofibrous silica–carbon based composites as anodic materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

In analytical science, it is always of great scientific and practical significances to explore convenient, rapid, and reliable methods/devices to trace the H 2 O 2 level in various matrices. Herein, we fabricated a ready-to-use paper-based chemosensor by using mesoporous carbon-dispersed Pd nanoparticles (Pd NPs/meso-C) as a promising peroxidase mimic for the visual determination of H 2 O 2 . Thanks to the large exposed surface of the meso-C support and the highly dispersed active Pd NPs, the synthesized Pd NPs/meso-C exhibited favorable catalytic performance to trigger the chromogenic reaction of colorless TMB to blue TMBox mediated by H 2 O 2 , providing a K cat of 326.67 s −1 for H 2 O 2 and 0.55 s −1 for TMB, larger than the bare Pd NPs and even comparable to the activity of natural horse radish peroxidase. As demonstrated, this principle could be employed to colorimetrically detect H 2 O 2 in the linear scope of 5–300 μM. By simply immobilizing the Pd NPs/meso-C mimic and the TMB substrate onto a common filter paper, ready-to-use paper-based sensors were further prepared. By combining these test strips with a smartphone and an easy-to-access color-scanning APP together, the integrated platform could be used for the quantitative analysis of H 2 O 2 with advantages of simple operation, fast response, low cost, and good selectivity and repeatability. Furthermore, reliable sensing of the target in milk matrices suggested great promise of the integrated platform in practical applications. [ABSTRACT FROM AUTHOR]

In this paper, we describe a novel carbon dot (CD) synthesized from citric acid and tyramine using a one-step microwave heating route. Under UV irradiation, the CD displayed blue emission that was quenched in the presence of H 2 O 2 and peroxidase. This property was used to quantify glucose in biological samples, using a standard additions procedure employing a paper platform and the H 2 O 2 formed in the enzymatic reaction with glucose oxidase. The attractive features of the paper platform include low cost, easy availability, biocompatibility, and hydrophilicity. The standard additions calibration method has the advantages that it can be performed using a single device, eliminates the need for external calibration, and reduces matrix effects associated with the sample and/or non-uniformity of the paper. The method developed was applied in the analysis of certified serum and urine samples. There were no statistically significant differences between the certified concentrations and the results obtained using the paper device with standard additions (Student's t-test at 95% confidence level). Image 1 • Green synthesis of carbon dots from citric acid and tyramine. • Carbon dots were prepared by a simple, fast, one-step microwave heating method. • Domestic microwave used to synthesize carbon dots. • Glucose determination using standard addition calibration method. • A simple, low-cost, portable, and eco-friendly paper platform method was developed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A CFMs-based RFP was proposed for ultrasensitive sensing of AO. • Dual-emissive CFMs were prepared by loading CDs into MF microspheres. • A smartphone-integrated paper device were prepared for AO visualization. A paper-based assay for visualization of auramine O (AO) was for the first time established by using CFMs as a ratiometric fluorescent probe (RFP). The CFMs were melamine formaldehyde microspheres (MFMs) incorporated with carbon dots (CDs), where the CDs species as sensing units and MFMs as a signal amplification carrier. The proposed RFP can quantitatively measure AO content from 0.0 to 10.0 μM and exhibited an ultralow limit of detection (LOD, 15.7 nM). In particular, obvious luminescence color change of CFMs from blue to green was perceived with naked-eyes and therefore, a solution-based and a paper-based visualization platform were respectively proposed for on-site visual detection of AO with LODs of 1.15 μM and 0.83 μM, separately. Finally, those fluorescence methods were adopted in sensitively quantitative measurement of AO within various food and drug samples, providing new prospects for analysts and technical support in food quality monitoring. [ABSTRACT FROM AUTHOR]

Highlights • MIPs/CDs grafted paper-based sensor for selective and sensitive determination of 3-MCPD. • CDs were intercepted in the paper and MIPs was also directly formed on the paper-based sensor. • The composites exhibited high adsorption capacity and excellent selectivity. • This method could be applied for the detection of 3-MCPD in soy sauce samples. Abstract 3-Monochloropropane-1,2-diol (3-MCPD) is a common food processing contaminant and a simple, rapid, sensitive and low cost monitoring technology is needed due to its potential carcinogenic nature. Carbon dots directly intercepted on filter paper provide high fluorescence intensity and can be adapted for use as a sensor. We synthesized a carbon dot-filter paper in combination with a molecularly imprinted polymeric film to extract 3-MCPD from samples. This grafted paper-based sensor exhibited a high adsorption capacity (68.97 mg g−1), an excellent selectivity (imprinting factor = 4.5) and a low detection limit (0.6 ng mL−1). Recoveries ranged from 97.2% to 105.3% with relative standard deviations <5.6%. The results obtained using this method were linearly correlated to those of the classic GC–MS method (r = 0.998). Based on the Chinese National Standard, this study provides a novel and powerful platform for the simple, rapid, sensitive and on-site analysis of 3-MCPD in soy sauce. [ABSTRACT FROM AUTHOR]

Rapid screening of bacteria by low-cost and eco-friendly material-based approaches is still a major challenge. Herein, a colorimetric biosensor was designed for the ultrasensitive and rapid detection of Gram-positive bacteria. The biosensor exploited polydopamine and polyethyleneimine (PDA-PEI)-modified papers for separating bacteria and carbon dots (CDs) for selective colorimetric detection of Gram-positive bacteria. Noble metal-free CDs can target Gram-positive bacteria by binding with peptidoglycan and possess peroxidase-like activity. Thus, they can avert the step of modifying recognition probes, facilitating biosensor fabrication, and reducing the cost. This biosensor can detect S. aureus as low as 1 cfu mL−1, L. monocytogenes as low as 5 cfu mL−1, and B. subtilis as low as 9 cfu mL−1 within 55 min. In addition, a portable device was constructed to enable convenient and on-site quantitative detection of Gram-positive bacteria. The feasibility of the biosensor was verified by detecting Gram-positive bacteria in eggshell and sausage samples with recoveries ranging from 91.2% to 110%. [Display omitted] • A colorimetric biosensor was developed based on PDA-PEI@paper and CDs. • The biosensor can selectively detect Gram-positive bacteria. • PDA-PEI@paper can enrich bacteria to improve sensitivity. • CDs with peroxidase-like activity can target Gram-positive bacteria. • The LODs of the biosensor for Gram-positive bacteria were less than 10 cfu mL−1. [ABSTRACT FROM AUTHOR]

• Freestanding carbon paper confined with ultrafine lithiophilic TiO 2 is in-situ synthesized from MXene and CO 2. • Freestanding C/TiO 2 paper is firstly employed as dendrite-free Li metal anodic host. • The growth behaviors of metallic Li on C/TiO 2 is systematically probed. • Lithiophilic TiO 2 seeds and conductive 3D carbon synergistically induce dendrite-free Li deposition. • C/TiO 2 @Li paper enables full cell with improved electrochemical performance. Lithium (Li) metal anode is deemed as one of the most fascinating anodes due to its high energy density. Nonetheless, low Coulombic efficiency and safety issues caused by detrimental Li dendrites growth severely hamper its practical application. Herein, we construct an ultrafine TiO 2 confined in 3D freestanding carbon paper by one-step green in-situ oxidation of Ti 3 C 2 T x MXene film with greenhouse gas CO 2. The lithiophilic TiO 2 seeds and freestanding 3D carbon matrix can synergistically induce uniform Li deposition and buffer the volume changes during lithium striping and deposition, which ensure improved electrochemical performance with high Coulombic efficiency and low overpotential, etc. The growth process of metallic Li on C/TiO 2 is also systematically investigated. Moreover, the C/TiO 2 @Li||LiFePO 4 full batteries present a stable cycling performance over 250cycles at 1.0C and superior rate performance. Additionally, this work proposes an alternative way to utilize CO 2 , which may alleviate greenhouse effect and boost sustainable development. These results may be useful for both the design of dendrite-free lithium metal batteries and the sustainable utilizing of CO 2. [ABSTRACT FROM AUTHOR]

Abstract Capacitive deionization (CDI) has emerged as an attractive approach for desalination and water treatment for its high energy efficiency, low cost, and easy regeneration. Here, we report the preparation and application of villiform carbon fiber paper (v-CFP) as the current collector for CDI device with high areal electrosorption capacity. The v-CFP was prepared by thermal annealing and subsequent O 2 plasma etching of the commercial pristine carbon fiber paper (p-CFP). With greatly improved surface area and hydrophilicity, the v-CFP itself showed an areal capacitance as high as 0.70 F·cm−2 in 0.5 M NaCl solution, and delivered an areal electrosorption capacity up to 122 and 400 mg·m−2 when feeding a NaCl solution with initial concentration of 50 and 3500 mg·L−1, respectively. Upon loading with additional electrode materials (EMs), e.g., graphene hydrogel, activated carbon, carbon nanotubes, and porous carbon spheres, the v-CFP/EM electrodes exhibited further improved areal electrosorption capacities, generally outperforming the corresponding p-CFP/EM electrodes by >2 times. Our studies demonstrate that proper surface treatment can largely improve the capacitance of the commonly used p-CFP current collector, making it greatly attractive in CDI devices. Graphical abstract Unlabelled Image Highlights • Annealing and O 2 plasma can improve the surface area and hydrophilicity of p-CFP. • The resultant v-CFP itself exhibits a high areal electroadsorption capacity. • The electrosorption capacity of v-CFP/AEM is higher 2 times that of p-CFP/AEM. • v-CFP has great potential as a new current collector in CDI device. [ABSTRACT FROM AUTHOR]

Abstract Carbon aerogel fiber-paper based electrodes were subjected to nitric acid treatment and gold deposition in this study of capacitive deionization (CDI) experiments. The performance of each electrode was assessed based on their adsorption capacities in four different electrode-configurations (two symmetric and two asymmetric). The characterization of the electrodes was conducted following scanning electron microscopy, three-dimensional laser confocal microscopy, cyclic voltammetry and Fourier transform spectroscopy. Surface area and porosity measurements were conducted using BET isotherm analysis. The highest salt removal capacity in this study was 8.0 mg/g of NaCl in asymmetric electrodes configuration with the gold-deposited electrode used as anode and untreated/uncoated electrode used as cathode. Highlights • Capacitive deionization with surface modification • Chemical treatment of CDI electrodes • Nitric acid treatment of CDI electrodes • Gold deposition on CDI electrode • Asymmetric capacitive deionization [ABSTRACT FROM AUTHOR]

Functionalized manganese-doped carbon dots (FMn-CDs) were prepared by integration of pyrolysis-derived Mn-CDs with ethylene diamine, ethylenediamine tetraacetic acid and Eu(III) ions. The FMn-CDs emitted intense blue fluorescence with high photostability, excellent water-solubility and favorable biocompatibility. 2, 6-dipicolinic acid (DPA) is an important biomarker of Bacillus anthracis spore . It serves as an antenna suction light group and can sensitize the Eu(III) combined on the FMn-CDs to produce bright red fluorescence. Benefitting from the absorbance energy transfer emission effect from DPA to the sensitized Eu(III), a ratiometric biosensor towards DPA detection was developed. The approach exhibited a linearity range from 0.1 to 750 nM and a detection limit of 0.1 nM. Moreover, visual FMn-CDs test paper was produced for the DPA detection using a smartphone under a portable UV lamp, with a lowest detection limit of 1 μM. This work revealed the potential of a convenient smart phone diagnostics for DPA detection using visual FMn-CDs test paper. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Designing and fabricating cheap and active bifunctional materials is crucial for the development of renewable energy technologies. In this article, three-dimensional nitrogen-doped porous carbon materials (NDPC-X, in which X represents the pyrolysis temperature) were fabricated by simultaneous carbonization and activation of polypyrrole-coated paper towel protected by a silica layer followed by acid etching. The material had a high specific surface area (1,123.40 m2/g). The as-obtained NDPC-900 displayed outstanding activity as a catalyst for the oxygen reduction reaction (ORR) as well as an electrode with a high specific capacitance in a supercapacitor in an alkaline medium. The NDPC-900 catalyst for the ORR exhibited a more positive reduction peak potential of −0.068 V (vs. Hg|HgCl 2) than that of Pt/C (−0.121 V), as well as better cycling stability and stronger methanol tolerance. Moreover, the NDPC-900 had a high specific capacitance of 379.50 F/g at a current density of 1 A/g, with a retention rate of 94.5% after 10,000 cycles in 6 mol/L KOH electrolyte when used as an electrode in a supercapacitor. All these results were attributed to the effect of a large surface area, which provided electrochemically active sites. This work introduces an effective way to use biomass-derived materials for the synthesis of promising bifunctional carbon material for electrochemical energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

Large volumes of engineered wood products (EWPs) and paper are routinely placed in landfills in Australia, where they are assumed to decay. However, the extent of decay for EWPs is not well-known. This study reports carbon loss from EWPs and paper buried in landfills in Sydney, Brisbane and Cairns in Australia, located in temperate, subtropical and tropical climates, respectively. The influence of pulp type (mechanical and chemical) and landfill type (municipal solid waste – MSW and construction and demolition – C&D) on decay levels were investigated. Carbon loss for EWPs ranged from 0.6 to 9.0%; though there is some uncertainty in these values due to limitations associated with sourcing appropriate controls. Carbon loss for paper products ranged from 0 to 58.9%. Papers produced from predominantly mechanical pulps generally had lower levels of decay than those produced via chemical or partly chemical processes. Typically, decay levels for paper products were highest for the tropical Cairns landfill, suggesting that climate may be a significant factor to be considered when estimating emissions from paper in landfills. For EWPs, regardless of the landfill type and climate, carbon losses were low, confirming results from previous laboratory studies. Lower carbon losses were observed for EWP and paper excavated from the Sydney C&D landfill, compared with the Sydney MSW landfill, confirming the hypothesis that conditions in C&D landfills are less favourable for decay. These results have implications for greenhouse gas inventory estimations, as carbon losses for EWPs were lower than the commonly assumed values of 23% (US EPA) and 50% (Intergovernmental Panel on Climate Change). For paper types, we suggest that separate decay factors should be used for papers dominated by mechanical pulp and those produced from mostly chemical pulps, and also for papers buried in tropical or more temperate climates. [ABSTRACT FROM AUTHOR]

A simple and inexpensive procedure of paper-based electrode (PE) fabrication using A4 size conventional paper, nail polish and carbon powder is reported. The device was prepared by spreading the carbon conductive ink directly onto the paper substrate using a paint-brush. The best composition of the conductive ink was 80:20% (m:m) carbon powder: nail polish and the best device was obtained with 100 mg (2.5 mg cm −2 ) of carbon conductive ink spread on the paper piece. The proposed device showed satisfactory stability in acidic, neutral and alkaline medium in presence of ferrocyanide ion used as electrochemical probe. Dopamine was selected as a target compound to evaluate the possibility of using the proposed device for electroanalytical purposes. Differential pulse voltammetry was used in these studies and dopamine detection was achieved at +0.13 V vs. Ag/AgCl sat in phosphate buffer solution pH = 7 with a detection limit of 5.2 μmol L −1 . The proposed device represents an interesting advance in the field of PE construction since it combines satisfactory electrochemical stability and electroanalytical performance with simplicity and widely available low-cost materials. Moreover, chemical modifiers can be easily added to the conductive ink. Therefore, this versatile device brings exciting possibilities for future electroanalytical applications mainly for those that require small and/or flexible devices, such as the amperometric detection in microfluidic systems. [ABSTRACT FROM AUTHOR]

Dissolved inorganic carbon (DIC) levels in freshwaters play a key role in the equilibrium of the carbon cycle between the atmosphere, water and living beings. Standard classical methods for DIC determination generally involve bulky and expensive equipment used in centralized laboratories, resulting in time-consuming processes that do not allow for adequate monitoring in the field. In order to address this challenge, we have developed a distance-based paper analytical device (PAD) for on-site determination of DIC in water. The portable, cost-effective and easy-to-use device was based on the miniaturization and integration of a classical acid-base colorimetric titration on a paper channel, enabling an accurate determination of DIC in less than 20 min. The length of the blue colored line in the detection channel after being filled with the sample was related to the DIC concentration in the sample. The reagent solution used to modify the titration channel was optimized so that DIC concentrations in the range 50–1000 mg L−1 could be measured. The long-term stability of the paper-based device was also evaluated, demonstrating a working stability for more than 70 days after their fabrication, an important characteristic for in-the-field analysis. Finally, the PAD was validated with different water samples, i.e. tap water, commercial bottled drinking water and water samples from a mine, with excellent agreement between the results obtained from the PAD and the standard method. This demonstrates the high potential of the proposed paper analytical device to quantify DIC in situ by minimally-trained personnel without the need for peripheral equipment, which represents an important advance compared to the current limited analysis systems. [Display omitted] • Paper-based analytical device (PAD) for dissolved inorganic carbon (DIC) determination. • Portable, cost-effective and easy-to-use device for on-site analysis in freshwater. • Long-term stability over more than six weeks • Validated with tap water, commercial bottled water and mine water samples. [ABSTRACT FROM AUTHOR]

Easily disposable low cost fuel cells as power sources are environmentally benign alternates to batteries for powering micro-analytical systems. In this regard, for the first time, an ethanol-dichromate fuel-oxidant microfluidic fuel cell is implemented on a paper scaffold. In this cell, a proton conducting poly (4-styrenesulfonate) based gel electrolyte enables proton transport from the anode to the cathode. Hydrothermally synthesized molybdenum oxide nanorods catalyze dichromate reduction and ethanol oxidation at the respective electrodes. A peak power density of 6.32 mWcm −2 is achieved with the catalyst. However, the cell without catalyst delivers a maximum power density of only 2.74 mWcm −2 . The compositions of the catholyte and anolyte streams and molybdenum oxide loadings are optimized. A stack of two cells connected in series illuminates a 3 mm red light emitting diode for over 40 min. This real time demonstration showcases the potential of this cell as an alternative to batteries for powering micro-analytical devices. [ABSTRACT FROM AUTHOR]

Large-sized graphene sheets (LG) and doping strategy were employed to fabricate lightweight and flexible graphene paper with exceptional electromagnetic interference (EMI) shielding performance. Compared with the smaller sized ones, LG with fewer defects and more conjugated carbon domain size as well as better alignment result in higher electrical conductivity and strength of graphene paper. The iodine doping further improves the carrier density of LG by formation of triiodide ( I 3 − ) and pentaiodide ( I 5 − ) through charge transfer process without deteriorating the mechanical property, thus leading to superior EMI shielding effectiveness (SE). The EMI SE of iodine doped LG film with thickness of 12.5 μm is up to ∼52.2 dB at 8.2 GHz, which is much higher than that of undoped LG with the same thickness (∼47.0 dB). More important, the improvements in EMI SE is contributed to the SE absorption, while the SE reflection is almost unchanged. The mechanisms of improved EMI shielding performance as well as mechanical property were investigated and discussed. The present study provides a facile way to fully develop graphene in lightweight and flexible EMI shielding materials and devices. [ABSTRACT FROM AUTHOR]

Chemical doping with nitrogen, phosphorus or halogens can effectively favor the room temperature phosphorescence (RTP) appearing of carbon dots (CDs) through facilitating their intersystem crossing (ISC) process. Here we raised a facile microwave strategy to synthesize nitrogen and phosphorus co-doped carbon dots (P-CDs), while triethanolamine served as the carbon source with phosphoric acid being the dopant. Meanwhile, the P-CDs showed both the bright-blue fluorescent emission and the green-RTP emission. Additionally, the filter paper functioned as the matrix to stabilize the triplet excitons of P-CDs, thus achieving their RTP emission by suppressing the non-radiative transitions. Significantly, an innovative painting technology of employing P-CDs as RTP-ink has been developed toward the confidential information encryption. Moreover, we applied the proposed P-CDs to respectively assay pH ranging from 9.15 to 13.55 and 2.29 to 13.55 by virtue of their pH-responsible fluorescence and RTP. Again, we further explored the fluorescent and phosphorescent sensing mechanism of P-CDs by the deprotonation of P–O bonds and the precipitation of P-CDs. Herein, a facile microwave strategy has been raised to synthesize nitrogen and phosphorus co-doped carbon dots (P-CDs), while triethanolamine served as the carbon source with phosphoric acid being the dopant. Meanwhile, the P-CDs showed both the bright-blue fluorescent emission and the green-RTP emission. Significantly, an innovative painting technology employing P-CDs as RTP-ink has been developed toward the confidential information encryption. Moreover, we applied the proposed P-CDs to respectively determine pH ranging from 9.15 to 13.55 and 2.29 to 13.55 by virtue of their pH-responsible fluorescence and RTP. Image 1 [ABSTRACT FROM AUTHOR]

Wood research has recently enjoyed a renaissance due to its emerging application in various fields. This is due to the natural reaction platform and hierarchical porous structure of wood, which allows it to combine perfectly with functional materials, especially nanoscale materials. Here, we report a portable fluorescent wood (FW) test paper based on the combination of wood and carbon dots (CDs) for rapid identification and detection of nitroaromatic explosives. Thereinto, the CDs optimize the assembly of wood and open up new functions, and the naturally porous structure of wood provides grid management for CDs, effectively avoiding the accumulation of CDs. Meanwhile, the CDs are immobilized in the wood skeleton via the multiple-blockades, and the fluorescence intensity is unaffected even under harsh environmental conditions, which ensures the FW test paper exhibits high sensitivity and selectivity for trinitrophenol. The quenching reached 100% by dropping 80 μM trinitrophenol with the ultrathin FW test paper (1 × 1 × 0.009 cm), and it is still significant in the presence of interference. Interestingly, the detection results can be monitored in real time with the naked eye. As far as we know, this is the first report of trinitrophenol detection with FW test paper. Illustration of proposed wood-based colorimetric test paper is encapsulated with fluorescent carbon dots for explosive detection. [Display omitted] • Fluorescence wood (FW) test was reported based on wood-nano and carbon dots. • FW test paper performed high sensitivity and selectively for TNP detection. • The TNP detection results can be directly observed by naked eye. • FW test paper showed excellent resistance performance in harsh environment. [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]

To enhance Pd electro-catalysts in their electro-catalytic activity for C-C bond breaking and tolerance stability, Pd was electrodeposited on high-porosity 3D reduced graphene oxide (rGO) aerogel paper. For comparison, the Pd was also coated on other three different carbon material surfaces: bare carbon fiber paper (CFP), and CFP modified with either 2D graphene oxide (GO) and 2D rGO nanosheets. The Pd/3D rGO aerogel paper exhibits higher catalytic activity toward the electro-oxidation of ethylene glycol in alkaline media and higher excellent tolerance stability than other electrodes due to ultra-high porosity of the 3D rGO support leading to high active electrochemical surface area of the as-fabricated Pd catalyst electrode. In addition, the hydrodynamic diffusion of ethylene glycol to the cayalyst surface investigated in this work plays a major role to the catalytic activity of the as-prepared electrocatalyst. The Pd/3D rGO aerogel rotating disk electrode exhibits a high anodic current density of 267.8 mA cm −2 at 3000 rpm. This high-performance Pd/3D rGO aerogel may be practically used as the high-efficiency anode of direct ethylene glycol and other related alcohol fuel cells. [ABSTRACT FROM AUTHOR]

This article details the study of electrochemical behavior of new carbon electrodes based on pyrolysis of different paper sources to be used in biosensor applications. The resistivity of the pyrolyzed papers was initially used as screening parameters to select the best three paper samples (imaging card paper, multipurpose printing paper, and 3MM chromatography paper) and assemble working electrodes that were further characterized by a combination of microscopy, electrochemistry, and spectroscopy. Although slight differences in performance were observed, all carbon substrates fabricated from pyrolysis of paper allowed the development of competitive biosensors for uric acid. The presented results demonstrate the potential of these electrodes for sensing applications and highlight the potential advantages of 3MM chromatography paper as a substrate to fabricate electrodes by pyrolysis. [ABSTRACT FROM AUTHOR]

Nowadays, selective, sensitive and visual detection of 2,4,6-trinitrotoluene (TNT) explosives residues in groundwater system has been a great challenge for human security. Herein, a visual fluorescence paper sensor for accurate and on-site detection of TNT in groundwater system by linking the recognition molecule onto the surface of the carbon quantum dots (CDs) was introduced. The fluorescence of CDs based nanosensor can be selectively and efficiently quenched by TNT through a photo-induced electron transfer effect between primary amino groups and TNT explosives. The fluorescence quantum yield of this kind of nanosensor is up to 32.25％ and the detection limit reaches as low as 0.213 μmol/L. The interference molecules, such as the nitrobenzene derivatives have no influence on the sensitive detection of TNT. Furthermore, the paper sensor based on the CDs probe has been prepared, which can efficiently detect TNT residues in groundwater system. This developed nanosensor possesses the great capability of on-site and visual detection of TNT residues in groundwater without any further processing step. [ABSTRACT FROM AUTHOR]

This paper reports a novel synthesis route to prepare an integrated gas diffusion electrode (I-GDE) consisting of self-supported N-doped nanonet by pyrolyzing polyaniline on carbon paper via the electrodeposition of aniline. Electrochemical experiments suggest that the integrated structure apparently improves the mass transport, electrical conductivity in the oxygen reduction reaction performance. The peak current density of the I-GDE achieves 0.71 mA cm −2 , which is almost two times to the conventional ink-based electrode fabricated with the same material under the same conditions. [ABSTRACT FROM AUTHOR]

Two instrument-free boron, nitrogen-doped carbon dots based fluorescent solid sensors (i.e. , test strips and hydrogel beads) are fabricated to sensitively monitor both Cu2+ and Co2+. [Display omitted] • Novel B, N co-doped carbon dots (BN-CDs) with bright tangerine fluorescence are solvothermally fabricated. • BN-CDs effectively detect both Cu2+ and Co2+ with high sensitivity and a low detection limit. • The joint effect of dynamic and static quenching mechanisms is proposed for fluorescence quenching by Cu2+/Co2+. • The BN-CDs based paper sensors exhibit rapid and sensitive response for Cu2+/Co2+ in an instrument-free manner. • The fluorescent BN-CDs/hydrogel conduct as sensor to sense Cu2+ and Co2+, and absorbent for removal of the ions. It is highly significant to develop water-soluble carbon dots (CDs) for ion detection in the environment via a facile and economical process. Herein, the organic molecules derived boron, nitrogen co-doped CDs (BN-CDs) with water-solubility are solvothermally synthesized towards dual ion detection. The BN-CDs emit bright tangerine fluorescence, and demonstrate a fluorescent quantum yield of 17 %. Besides, the obtained BN-CDs show a good linear relationship with Cu2+/Co2+ in a wide dynamic range of 1–8 μM, along with detection limits of 16 nM (Cu2+) and 24 nM (Co2+). The joint effect of dynamic and static quenching mechanisms is proposed as well for fluorescence quenching by Cu2+/Co2+. Furthermore, two instrument-free BN-CDs-based solid sensors (i.e. , test strips and hydrogel beads) are fabricated to sensitively monitor both Cu2+ and Co2+. The paper-based sensors exhibit selective and sensitive response towards Cu2+ and Co2+ in a low-cost manner. The fluorescence hydrogel integrates comprehensive advantages of hydrogel and BN-CDs, which makes it not only conduct as efficient fluorescent sensors to detect Cu2+ and Co2+ but act as the absorbent towards removal of the ions. The simple yet reliable sensing technique developed here favor efficiently detecting and recognizing dual ions in environmental and/or biological samples. [ABSTRACT FROM AUTHOR]

The surface of paper was treated to control wettability using argon-carbon plasma generated by a direct current-pulsed (frequency: 60 kHz) sputtering device with parallel-arrangement magnets. After plasma treatment, the C–C bond percentage in the C 1s region was inversely proportional to the C–OH bond percentage, while the ratio of C=O and O–C=O bonds only changed slightly. The change ratios for the increase in C–C and the decrease in the C–OH bonds were approximately the same, and the change ratio increased from approximately 5%–11% with an increase in the plasma current. The reduction ratio of the contact angle decreased from 0.945 to 0.182 (°/s) with increasing plasma current. These results indicate that the water resistance of the paper surface was enhanced after the simple plasma treatment, and wettability could be easily controlled by changing the substitution ratio between C–OH and C–C elements, achieved by altering the plasma current. • Papers were plasma-treated using DC-pulsed sputtering with parallel-aligned magnets. • C–C and C–OH bond percentages were inversely proportional after plasma treatment. • Substitution ratio between C–OH and C–C was changed by varying the plasma current. • Contact angle reduction ratio on paper decreased with increase in plasma current. [ABSTRACT FROM AUTHOR]

Carbon dots (C-dots), a new class of non-toxic carbogenic nanomaterials have attracted lots of attention. By using simple microwave heating of a biocompatible biological media such as potato-dextrose agar (PDA), the newly synthesized C-dots not only showed its potential application on the ultrasensitive and highly selective Lead (Pb 2+ ) detection in solution but also in paper based sensor strips. The detection limit (DL) of Pb 2+ was found to be 106–110 pM both in solution and on a paper based strips sensor. The fast kinetic data suggested on spot real time Pb 2+ detection. Finally, it showed the potential Pb 2+ sensing in human cells. [ABSTRACT FROM AUTHOR]

We propose an innovative 3-step manufacturing technique for the synthesis of the catalyst layer of proton exchange membrane electrodes directly over a gas diffusion layer consisting of carbon paper (CP). In the first step, a carbon synthesis catalyst was formed in a bicontinuous microemulsion. In the second step, carbon nano-networks (CNNs) were directly grown over CP by thermal chemical vapor deposition of ethene over the metal catalyst embedded in the simultaneously carbonized microemulsion matrix. In the third step, the electrocatalyst, here Pt, was deposited on the CNNs. The influence of surfactant type, Na-AOT or Triton X-100, carbon synthesis catalyst type, Fe, Co or Pt, and loading on the electrolyte accessible surface area (ESA) and carbon corrosion resistance was evaluated in a three-electrode half-cell. CNNs grown from Fe and synthetized in Na-AOT microemulsions resulted as the best combination in terms of ESA and carbon corrosion resistance and were used for subsequent investigations. The CNNs grown on CP (CNNs/CP) were electrochemically oxidized prior to Pt electro-deposition by means of potential cycling. The effect of oxidation of the CNNs on the size and spatial distribution of the electrodeposited Pt catalyst was evaluated. Increasing the number of functionalizing oxidation cycles from 0 to 100 decreased the average catalyst crystallite size from 19 to 9 nm. The CNNs/CP samples showing the highest electrochemically active surface area (ECSA) were compared to a commercial catalyst with respect to ECSA, catalyst utilization, and durability to potential cycling. The ECSA for the CNNs/CP samples turned out to be lower than that of the commercial catalyst due to the larger catalyst size. On the other hand, the CNN/CP samples proved to be more durable and higher Pt utilization was achieved. [ABSTRACT FROM AUTHOR]

Hierarchically porous Cu–Ni/C composite catalysts were successfully fabricated by a bio-inspired route involving impregnation and calcination processes. Macoporous networks composed of interwoven carbon fibers loaded with nano Cu–Ni particles, which had high surface area (538 m 2 /g), were prepared by template-directed synthesis employing tissue paper as bio-templates. The obtained hierarchically porous structures exhibited high catalytic activity for acid fuchsin degradation in the MICO process due to the synergetic effects between the microwave (MW), porous carbon and Cu–Ni nano particles. The degradation of acid fuchsin was a fast process under MW irritation. Not only the chromophore group but also the naphthalene ring and benzene ring in acid fuchsin molecule can be destroyed mostly. Ni addition had a significant effect on the acid fuchsin degradation because it benefited more formation of hydroxyl radicals OH under MW irritation. [ABSTRACT FROM AUTHOR]

Wood has always been an indispensable material in human society throughout history. Its efficient utilization is even more crucial today in achieving the Sustainable Development Goals (SDGs). However, its production, trade, use, and recycling are seldom systematically assessed, with Germany being an exception due to the extensive work conducted by the University of Hamburg and the Thünen Institute over the years. To provide a more precise account of wood use, this study employs oven-dry metric tonne as the reference unit to construct a static wood flow based on the material flow analysis and wood resource balance in Germany in 2020. The Sankey diagrams comprehensively visualize the flow and stock of wood in various sectors, including forests, sawmills, pulp mills, buildings, energy, and waste. Results showed that forest felling volume exceeded growth due to significant wood demand and export, while forest carbon sinks increased because more hardwood was retained in German forests. The building and construction sector was the largest consumer of primary wood products, accounting for 52.1 % of the total, followed by furniture (29.5 %) and packaging (14.0 %). All waste paper was used to produce recycled fiber pulp, whereas only 14 % of waste wood was employed in particle board production. The woody biomass energy, amounting to 142.4 TWh, provided approximately 4.4 % of Germany's primary energy consumption, with around half of it used in private households. In addition to apparent data, this study also uses resource allocation, carbon storage, and cascade potential as examples to demonstrate that wood flow is applicable for further in-depth analysis, supporting wood efficient utilization. It can even be applied to any country and period with sufficient data and conversion factors, but here, they also prevented this study from comprehensively describing past and future wood flows. [Display omitted] [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) have been widely used for sterilization due to their broad-spectrum bactericidal properties. However, there exist the problems of premature releasing and accumulative toxicity when free AgNPs are applied. This study proposed a one-pot hydrothermal strategy to synthesize carbon spheres immobilized silver nanoparticles (AgNPs@CS). The synthesis involves with silver ammonia solution as Ag precursor, and corn stalk as green reducing agent and carbon precursor. Furthermore, AgNPs@CS was anchored by cellulose nanofibers (CNF) to obtain the antibacterial composite paper. The obtained CNF/AgNPs@CS paper exhibited superior antibacterial properties against E. coli and S. aureus. Notably, the accumulative release rate of AgNPs from AgNPs@CS was 10.2% in 9 days, while that from CNF/AgNPs@CS paper was only 6.7% due to the anchoring effect of both CS and CNF, which was low for avoiding the cumulative toxicity problem. In addition, the mechanical and barrier properties of CNF/AgNPs@CS paper were also improved by 29.4% (tensile index), 2.7% (tear index), 7.4% (burst index), 10% (folding endurance), 0.8% (water vapor transmission) and 9.4% (oxygen transmission rate), respectively. Therefore, the composite paper has potential application as a medical antibacterial material. • AgNPs were synthesized in carbon sphere (CS) by one-pot hydrothermal strategy. • AgNPs@CS were further immobilized by cellulose nanofibers to obtain composite paper. • The accumulative release rate of AgNPs from composite paper was low and safe. • The composite papers exhibited excellent antibacterial properties on E. coli and S. aureus. • The composite paper showed satisfactory mechanical and barrier properties. [ABSTRACT FROM AUTHOR]

• A carbon nanoparticles-embedded paper-based analytical device (CNP-PAD) is developed to quantify hemoglobin concentration. • The fabrication technique combined the CNP synthesis and embedment processes into a facile single-step procedure. • CNP-PAD uses cellulosic paper as the sole fabrication material. • Synthesized CNP was comprehensively characterized to ascertain its optical property and chemical compositions. • CNP-PAD's applicability as a biosensor to detect the alterations in hemoglobin (Hb) concentration was demonstrated. The embedment of carbon nanoparticles (CNPs) on paper-based analytical devices (PADs) possesses great potential as a biosensing platform owing to the synergistic combination of their respective advantageous properties. However, their applicability in actual biomedical scenarios is undermined by their cumbersome fabrication process. Here, we present a CNP-embedded PAD (CNP-PAD) that is fabricated through a one-step laser engraving method. We demonstrate the ultra-fast in situ synthesis (< 20 s) of CNPs (diameter = 23 ± 9 nm) with cellulose paper by simple laser engraving. The CNP-PAD was characterized and optimized for hemoglobin measurements. Validation results obtained with human blood samples demonstrated a high degree of agreement (Pearson correlation coefficient = 0.97) with the standard laboratory measurement approach (cyanmethemoglobin method). This work creates a nexus between the fields of CNP and PAD, presenting advantages that highlight its suitability for accessible anemia diagnostics, particularly in resource-limited environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sensitive : carbon dots were sensitive to pyrimethanil (PMT) yielding LOD of 14 nM. • Selective : carbon dots were selective to PMT against several interferences. • Accurate : concentrations of PMT in real samples were accurately determined. • Reusable : paper-based sensor produced excellent results even after 8-time uses. • Fast : the sensor gave the detection results within 30 s. Novel sensors based on fluorescent carbon dots were developed for a rapid, selective, and sensitive detection of pyrimethanil, a fungicide widely used in many agricultural crops. The carbon dots were synthesized from maleic anhydride and triethylenetetramine via a facile one-pot pyrolysis. A quenched fluorescence intensity of carbon dots in the presence of pyrimethanil occurred via inner filter effect and strong π-π interaction. The carbon dots were sensitive to pyrimethanil across a linear range from 0.5 to 75 µM with a low detection limit of 14 nM. The sensing results could be generated in 30 s. The fluorescent carbon dots showed excellent stability and selectivity to pyrimethanil in the presence of interferences, including fungicides and metal ions. They were also successfully employed for pyrimethanil detection in apples, cucumbers, and drinking water, yielding 98.6–107.1% recovery. The practical, portable, and reusable paper-based sensor was also developed. The cytotoxicity of carbon dots was tested to demonstrate that they are sufficiently safe to use. The novel pyrimethanil sensor based on fluorescent carbon dots developed in this work can be used as a high-performance sensor and a rapid tool for quality control in food, agricultural, and environmental monitoring. [ABSTRACT FROM AUTHOR]

Tricolor emissive CDs with multiple-cores@shell structure were synthesized by one-pot hydrothermal route. The surface Aphen moieties endow the as-synthesized AC-CDs with promising pH-sensitive function to prepare fluorescent pH test paper towards qualitative and quantitative detection of pH in the solution. CDs can be used as a cell imaging marker and efficient cellular labelling to detect intracellular pH due to its unique tricolor emission property. • Tricolor emissive CDs with multiple-cores@shell structure were synthesized by one-pot hydrothermal route. • The as-obtained CDs were used to prepare fluorescent pH test paper with promising pH-sensitive feature. • CDs can be used as a cell imaging marker and efficient cellular labelling to detect intracellular pH. • Unique tricolor property of CDs can avoid the fluorescent dyes and protein fluorescence interference for cell imaging. Recently, fluorescent pH test paper has been extensively explored for visual assays due to its easy preparation, low-cost, and portable feature. In addition, intracellular pH also plays important roles in different pathological and physiological processes for understanding cellular functions and providing critical assistance for early disease diagnosis. Herein, the tricolor emission multiple-cores@shell carbon dots (CDs) were synthesized via one-pot hydrothermal method using 5-amino-1,10-phenanthroline (Aphen) and citric acid (CA) as the carbon sources. The fluorescence emission of CDs showed an interesting pH dependence due to the special structure and properties, which can make the CDs to be used as the pH test paper to qualitatively and quantitatively detect pH value in a wide pH range. At the same time, because of good cell compatibility and low toxicity, CDs can be used as a new type of cell imaging marker to detect intracellular pH. The unique tricolor emission property of CDs can well avoid the fluorescent dyes and protein fluorescence interference. [ABSTRACT FROM AUTHOR]

[Display omitted] • By slow pyrolysis, pulper waste is converted into a stable, carbon-rich material. • Chemical leaching upgrades the carbon-rich solid to a fossil coal substitute. • The process enables to recover more than 90 % of Ca and Al from pulper waste. • By precipitation, a reusable Al-based flocculating agent is obtained. • Clean hydrogen is produced by the reaction between metallic Al and HCl. This work aims to investigate the potentials of integrating slow pyrolysis and chemical leaching to recycle pulper waste (PW), the waste generated by paper mills, and consists of plastics, metallic films, and biobased polymers. The concentration of chlorine and metals is a barrier against PW valorisation by combustion or high temperature thermochemical processes. In this study, PW was tested by slow pyrolysis at 400 °C and 500 °C. Chemical leaching tests were performed by processing both chars in a 1.4 M HCl solution, at 80 °C for 2 h, to remove inorganic compounds and upgrade the char to a coal-like material. Then, precipitation by NaOH was conducted on the leachate. Slow pyrolysis led to a char mass yield around 30 %. Due to the high inorganic matter concentration (almost 36 %, mainly including chlorine, calcium, and aluminium), the char retained only 25 % of the feedstock's chemical energy, while the remaining 75 % was recovered in the pyrogas. Leaching of the 500 °C pyrolysis char led to extract 93 % of aluminium, and almost 100 % of calcium and chlorine, resulting in an upgraded char containing 15.5 % ash, comparable to a fossil coal. By char leaching, the oxidation reaction of aluminium could produce 8 kg hydrogen per dry ton PW. The effectiveness of the precipitated compounds as flocculating agents was demonstrated, enabling a closed-loop recycling in the same paper mill. In conclusion, the proposed process demonstrated to be an effective solution to convert PW into high quality products. [ABSTRACT FROM AUTHOR]

Based on simulation data we show that the edge graphite atoms of a HOPG surface have remarkable influence on water contact angle values. Compared to graphite basal plane, a water droplet sitting on the edge atoms experiences two effects on wettability, smaller density of surface carbon atoms and the appearance of the Wenzel states. The differences between contact angles recorded for samples containing different amounts of the edge atoms are large, even after carbon surface oxidation. Thus, we report anisotropic wettability of the graphite surface. Moreover, changing the content of edge atoms in the substrate, one can induce switchable hydrophilic/hydrophobic properties of graphite. [ABSTRACT FROM AUTHOR]

• New cobalt metal-organic framework modified carbon cloth/paper (Co-MOF/CC/Paper) hybrid button-sensor. • Portable, robust, and user-friendly electrochemical analytical chip for nonenzymatic glucose sensing. • Effectively increasing the specific area and catalytic sites based on the Co-MOF/CC interface. • Low-cost and simple on-chip application with desired selectivity, stability, and durability in complex biomatrixes. In the growing pandemic, family healthcare is widely concerned with the increase of medical self-diagnosis away from the hospital. A cobalt metal-organic framework modified carbon cloth/paper (Co-MOF/CC/Paper) hybrid button-sensor was developed as a portable, robust, and user-friendly electrochemical analytical chip for nonenzymatic quantitative detection of glucose. Highly integrated electrochemical analytical chip was successfully fabricated with a flexible Co-MOF/CC sensing interface, effectively increasing the specific area and catalytic sites than the traditional plane electrode. Based on the button-sensor, rapid quantitative detection of glucose was achieved in multiple complex bio-matrixes, such as serum, urine, and saliva, with desired selectivity, stability, and durability. With the advantages of low cost, high environment tolerance, ease of production, our nanozyme-based electrochemical analytical chip achieved reliable nonenzymatic electrocatalysis, has great potential for the application of rapid on-site analysis in personalized diagnostic and disease prevention. [ABSTRACT FROM AUTHOR]

• We have designed a new colorimetric and chemiluminescence paper sensor for sensitive detection of cytochrome C. • β-Co(OH) 2 nanoplates anchored on ordered mesoporous carbon (CMK) were synthesized by electrochemical method. • CMK could be a sufficient catalyzer in chemiluminescence and colorimetric system. • The proposed aptasensor shows a detection limit of 1.0 × 10−9 M and a detection limit of 2.0 × 10−14 M in colorimetric chemiluminescence detection systems, respectively. The detection and measurement of Cytochrome C (Cyt c) has a large impact on the early detection of various types of cancers. So there is a need for developing simple and rapid methods that can be offset by advances in the use of test strips. In this work, a chemiluminescence (CL) and colorimetric aptasensor based method for highly sensitive detection of Cyt c in solution and on paper is introduced. We found that new nano-based material composed of β-Co(OH) 2 nanoplates anchored on ordered mesoporous carbon (CMK) could be a sufficient catalyzer in chemiluminescence and colorimetric systems. In the presence of Cyt c , its specific aptamers would bind to Cyt c and β-Co(OH) 2 CMk can become free thus enhancing the intensity. While in the absence of Cyt c , a weak CL signal was produced, because β-Co(OH) 2 CMK will be surrounded by aptamers. The proposed aptasensor exhibited a wide dynamic range from 5.0 × 10−8–1.0 × 10−3 M (R2 = 0.99) with a detection limit of 1.0 × 10−9 M in colorimetric and 10 × 10−13–5.0 × 10−9 M (R2 = 0.99) and a detection limit of 2.0 × 10−14 M in chemiluminescence detection systems, which was applicable for the determination of Cyt c efficiently. Also, we tested this strategy on paper for both colorimetric and chemiluminescence detection that showed the convenient response according to the obtained results. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) have attracted intense scientific attention as the most promising next generation energy storage device. However, the large-scale practical application of SIBs has been limited by exploring a low-cost and high performance anode material. Herein, hard carbon microfibers are successfully synthesized from renewable paper via simply carbonization procedure and proposed as anode materials for SIBs. The optimized carbonization at 1400 °C endows hard carbon microfibers high reversible charge capacity of 319.6 mAh g−1, good rate capability as well as excellent cycle life with capacity retention of 99.3% after 100 cycles. The sodium storage mechanism is further investigated by virtue of various technologies, indicating that sodium ions are stored in inter- and intra-layers. Remarkably, a full cell with the as-prepared anode and a Na 3 V 2 (PO 4) 3 cathode shows a favorable capacity of 243.8 mAh g−1 and stable cyclability of 218.9 mAh g−1 after 100 cycles. This study provides an opportunity for a cost-effective and renewable anode material for SIBs. [ABSTRACT FROM AUTHOR]