Search

The combination of electrochemistry and mass spectrometry is a powerful analytical tool for studying redox reaction mechanisms and identifying products or intermediates. However, the previously reported devices all require bespoke fabrication and are too complicated to be assembled and used by others. Crucially, the long ion transport distance and small spray volumes make it difficult to capture the short-lived intermediates. We present a practical mass spectrometric method in which surface-modified carbon fiber paper is innovatively applied to detect electrogenerated intermediates. Treating carbon fiber paper with dilute nitric acid removes its surface impurities, enhancing the capability of electro-redox. Electrospray ionization and redox reaction occur simultaneously on the tip of the paper. Transient electro-redox species generate and transfer into gas phase as soon as the appearance of spray. Rapid transport of quantities of electrogenerated ions to the mass spectrometer inlet makes it possible for mass spectrometric identification on the millisecond scale. The short-lived radical cations and iminium ions were successfully captured, reflecting the starting step of the cross-dehydrogenation coupling reaction. The real-time oxidation and online functionalization reactions of tertiary amines were achieved using this device without additional oxidants and electrolytes. In this way we could achieve in-depth mechanistic understanding and rapid screening of serial reactions. [Display omitted] • Treating carbon fiber paper with dilute nitric acid enhances the capability of detecting electrogenerated intermediates. • A-CFPSI permits the real-time monitoring of electrochemical reaction intermediates on the millisecond scale. • No additional electrolytes and oxidants are required, avoiding interference with the mass spectrum. • A-CFPRSI can be used for rapid screening of electrochemical reactions and mechanism researches. [ABSTRACT FROM AUTHOR]

[Display omitted] • Free-standing composite papers of SFCP@PANI were prepared. • The free-standing SFCP@PANI-2 paper was directly utilized as supercapacitive electrodes. • The SFCP@PANI-2 demonstrated an enhanced electrochemcial capacitive performance. Free-standing composite papers of SFCP@PANI were prepared by in situ polymerization of aniline on the surface of sisal fiber carbon paper (SFCP). The SFCP@PANI papers can be directly built into electrodes without the need for any binders or conductive agents. SFCP@PANI-2 exhibits excellent electrochemical performance in the three-electrode system and the coin-type symmetric supercapacitor (SSC), which indicates that it may be a promising electrode material for supercapacitor. [ABSTRACT FROM AUTHOR]

The electrochemical oxidation of paper mill wastewater belonging from Halfa industries (Tunisia) was performed by galvanostatic electrolysis using boron-doped diamond (BDD) anodes and Ti-Ru-Sn ternary oxide (TiRuSnO 2 ). The effect of several operating parameters, such as applied current density, flow rate, temperature, initial pH value and addition of NaCl was evaluated. Chemical oxygen demand (COD) and ammonium measurements were carried out to study the treatment of the actual wastewater. The energy consumption analysis has been also discussed. The experimental results exhibited that galvanostatic electrolyses with BDD always allowed efficient COD removal in any conditions thanks to the reaction with hydroxyl radicals electrogenerated on BDD surface during electrolysis. On the contrary, using the TiRuSnO 2 anode, the complete COD removal was only obtained in the presence of chloride ions. Comparison of the results of the two electrodes showed that BDD provided a faster removal with higher efficiency and lower energy consumption, while TiRuSnO 2 was more efficient for ammonium removal. [ABSTRACT FROM AUTHOR]

A simple synthetic chemical process to produce metal oxide loaded carbon papers was developed using bacterial cellulose gel, which consisted of nanometer-sized fibrous cellulose and water. Metal ions were successfully impregnated into the gel via aqueous solution media before drying and carbonization methods resulting in metal oxide contents that were easy to control through variations in the concentration of aqueous solutions. The papers loaded by molybdenum oxides were characterized as pseudocapacitor electrodes preliminary, and the large redox capacitance of the oxides was followed by a conductive fibrous carbon substrate, suggesting that a binder and carbon black additive-free electrode consisting of metal oxides and carbon paper was formed. [ABSTRACT FROM AUTHOR]

This study analyzed theoretically the effects of a carbon paper (CP)-based electrode on the performance of a vanadium redox flow battery (VRFB). Compared to conventional carbon felt-based electrode materials, the CP-based electrode showed superior characteristics in facilitating the redox reactions of VO 2+ / VO 2 + and V 2+ / V 3+ couples, such as better electrochemical activity and higher electronic conductivity. A three-dimensional, non-isothermal VRFB model developed in a previous study was applied to a range of single cell structures equipped with CP-based electrodes and flow channels in the current collectors. The model was then validated using the experimental data measured under the CP- and channel-based VRFB geometries. The model successfully captured the experimental trend that showed a higher discharging performance with increasing number of CP layers used for each electrode. The simulation results clearly showed that the activation overpotentials in the electrodes were reduced significantly using more CP layers, which dominated over the effects of increased mass transport limitation of vanadium ions due to the thicker electrode. [ABSTRACT FROM AUTHOR]

[Display omitted] • It is easier and cheaper to produce sisal fiber carbon paper supercapacitor electrodes in various shapes. • The free-standing SFCPs were directly utilized as supercapacitive electrodes. • SFCP-900 exhibited relatively good electrochemical properties in supercapacitor. Sisal Fiber Carbon Papers (SFCPs) with high specific surface area was obtained using a simple hydrothermal, pressing and carbonization method. The effects of calcination temperature on morphology, structure, pore structure and electrochemical properties of SFCPs were systematically studied. The free-standing SFCPs were directly utilized as supercapacitive electrodes, and the results revealed that the SFCPs calcinated at 900 °C (SFCP-900) exhibit a better specific capacity than SFCP-800 and SFCP-1000. These results suggested that the SFCP-900 has potential applications in supercapacitors. [ABSTRACT FROM AUTHOR]

A novel 3D paper-based microfluidic screen-printed electrode (SPE) composed of two layers was constructed by photolithography and screen-printing technology. Aldehyde functionalized hydrophilic zone of the counter and reference electrodes layer was prepared for glucose oxidase immobilization. Highly conductive prussian blue deposited reduced graphene oxide-tetraethylene pentamine (rGO-TEPA/PB) modified paper working electrode layer can be used as an electrochemical sensitive membrane for quantitative detection of hydrogen peroxide (H 2 O 2), which was the enzyme-catalyzed reaction product. Therefore, this 3D paper-based microfluidic electrochemical biosensor can be used for quantitative detection of glucose. Under optimum conditions, the proposed biosensor can be used for quantitative determination of glucose over a wide linear range of 0.1 mM–25 mM with detection limit of 25 μM. Finally, the 3D paper-based microfluidic electrochemical biosensor was applied to determine glucose in human sweat and blood, and the obtained results were in good consistency with values measured by Roche's blood glucose meter. In addition, the proposed 3D paper-based electrochemical device showed good repeatability, stability, and anti-interference, which would be of great potential to monitor glucose in complex biological fluids. A novel 3D paper-based microfluidic screen-printed electrode composed of two layers was constructed by photolithography and screen printing technology. Aldehyde functionalized hydrophilic zone of the counter and reference electrodes layer was prepared for glucose oxidase immobilization. Highly conductive Prussian blue deposited reduced graphene oxide-tetraethylene pentamine modified paper working electrode layer can be used as an electrochemical sensitive membrane for quantitative detection of H 2 O 2 , which was the enzyme-catalyzed reaction product. Therefore, this 3D paper-based microfluidic electrochemical biosensor can be used for quantitative detection of glucose. Under optimum conditions, the proposed biosensor can be used for quantitative determination of glucose over a wide linear range of 0.1 mM–25 mM with detection limit of 25 μM. Image 1 • A paper based electrochemical approach for the determination of glucose is presented. • Enhanced stability, good selectivity, outstanding simplicity and low-cost biosensor. • Validation with the determination of glucose in human sweat and blood shows very good results. [ABSTRACT FROM AUTHOR]

Highlights: [•] Microbial bioanodes were formed in raw pulp and paper mill effluent. [•] In well-controlled conditions 4A/m2 were reached at −0.3V/ECS. [•] A theoretical model determined the contribution of the bioanode to the COD removal. [•] Electrochemical COD removal was proportional to HRT. [•] Electrochemical COD removal obeyed a Michaelis–Menten law with the COD outlet. [ABSTRACT FROM AUTHOR]

Abstract A facile one-step solid-phase synthesis strategy is developed for synthesizing a binder-free molybdenum disulfide/carbon fibers paper (MoS 2 /CFP) anode. The microstructure, composition, morphology and electrochemical performances were investigated. It is found that the thin MoS 2 layers are well anchored on the interlaced carbon fibers to form MoS 2 /CFP, which has mesoporous structure and large specific surface area of ∼18.8 m2g-1. As a result, the obtained MoS 2 /CFP anode exhibits a reversible capacity of 261 mAh·g−1 with 31.2% loading ratio of MoS 2. After subtracting the capacity of CFP, the MoS 2 in the composite anode delivers a reversible capacity of 539 mAh·g−1 and shows better cycle stability than commercial MoS 2 after 100 cycles at 100 mA g−1. The remarkable electrochemical performances could be attributed to the buffer space among carbon fibers for the volume changes of MoS 2 as well as the highly conductive carbon fibers network, suggesting that the MoS 2 /CFP is a promising binder-free anode for lithium-ion batteries. Graphical abstract Image 1 Highlights • A one-step solid-phase synthesis strategy is developed to fabricate MoS 2 /CFP anode. • The MoS 2 and the carbon matrix of MoS 2 /CFP composite were synthesized synchronously. • The MoS 2 /CFP anode exhibits enhanced cycling performance and high-rate capability. • The mechanism of the enhanced electrochemical properties was discussed for MoS 2 /CFP. [ABSTRACT FROM AUTHOR]

Abstract: This laboratory study aims at improving the treatability of bleaching effluents from local pulp and paper mills using individual physico-chemical treatments like chemical precipitation and electrochemical treatment. Advanced oxidation processes (AOPs) such as ultrasonic irradiation in combination with Fenton-like oxidation (Fe3+/H2O2) or photo-Fenton degradation (Fe2+/H2O2/UV) were also separately tested. Effects of operating parameters such as pH and oxidant''s dose on the removal of organic compounds were investigated in terms of COD removal. Of the various treatments, chemical precipitation using 5g/L of CaO was the most effective to remove organic compounds from the samples, as indicated by their decreasing COD concentrations up to 90% at an initial concentration of 1510mg/L at pH 12. At initial concentrations ranging from 2.5 to 12.5mg/L, this method could remove over 90% of target compounds such as abietic acid, linoleic acid, and β-sitosterol from bleaching effluents. Although each individual treatment could improve the treatability of bleaching wastewater, neither of them could generate treated effluents that met the strict requirement of COD limit of less than 200mg/L, thus suggesting the need for integrating physico-chemical treatments and biological process to complement the degradation of recalcitrant compounds in the samples prior to their discharge. [Copyright &y& Elsevier]

Abstract: A commercial rice paper (RP) is used for the first time as a separator membrane in lithium-ion batteries. It consists of interpenetrating cellulose fibers with a diameter of about 5–40μm to form a highly porous structure. The RP is found to be electrochemically stable at a potential below 4.5V vs. Li+/Li. Several kinds of electrode materials including graphite, LiFePO4, LiCoO2 and LiMn2O4 are used to test the compatibility of the RP in Li-ion batteries and to compare with a commercial polypropylene/polyethylene/polypropylene separator membrane. The RP separator with the same thickness gives rise to a lower resistance than the commercial separator. Due to the wonderful flexibility, high porosity, low cost and excellent electrochemical performance of the RP membrane, it is promising to partially replace commercial separators in lithium-ion batteries for low power applications. [Copyright &y& Elsevier]

Abstract: Carbon nanowall films were synthesized by plasma enhanced hot filament chemical vapour deposition on carbon paper, a three dimensionally structured material. The micro-structured nature of the carbon paper, which is composed of an irregular and open mesh of carbon fibres, allowed one to determine the microstructure of the carbon nanowalls both at the tip and at the fibre–nanowall base interface. The number of graphenes which pile up to form the structure of a single nanowall ranges from 1 to 2 at the tip up to several 10s at the base, making this material suitable to study and eventually exploit the electronic properties of graphenes on a macroscopic scale. Such material is promising for electrochemical applications. [Copyright &y& Elsevier]

Abstract: Electrochemical treatment of organic pollutants is a promising treatment technique for substances which are resistant to biodegradation. In this study an electrochemical treatment based on the principle of anodic oxidation was used to treat paper mill effluent from Rakta''s Pulp and Paper Company where rice straw is used to produce paper pulp. Experiments were carried out in a cylindrical agitated vessel lined with lead sheet as anode while a concentric cylindrical stainless steel sheet screen was placed as a cathode. The effect of current density, pH, NaCl concentration, impeller rotational speed and temperature on the rate of color and COD removal was studied. The results showed that the use of electrochemical technique reduces the COD from an average value of 5500 to 160. The percentage color removal ranged from 53% to 100% depending on the operating conditions. Energy consumption calculation shows that energy consumption ranges from 4 to 29kWh/m3 of effluent depending on the operating conditions. The experimental results proved that the electrochemical oxidation is a powerful tool for treating paper mill effluents where rice straw is used as a raw material. [Copyright &y& Elsevier]

A novel microfluidic paper-based analytical device (μPAD) was developed with benzoquinone (BQ)-mediated E. coli respiration method to measure the biotoxicities of pollutants. Functional units including sample injection, fluid-cell separation, all-carbon electrode-enabled electrochemical detection, were integrated on a piece of chromatography paper. The three-electrode, working electrode, counter electrode and reference electrode, were simultaneously screen-printed on the μPAD with conductive carbon ink. The satisfying electrochemical performance of the paper-based carbon three-electrode was confirmed by cyclic voltammetry detecting K 3 [Fe(CN) 6 ]. The process of cell toxication was considered that toxicants inhibited cell respiration and diminished the electrons on E. coli respiratory chain. It was quantitatively reflected by measuring oxidation current of hydroquinone (HQ) as a reduced state of the redox mediator BQ after the incubation of cells with pollutants. The current detection time, BQ concentration and E. coli incubation time were carefully optimized to establish the systematic optimized operations of BQ-mediated E. coli respiration method. Using the fabricated μPAD the half inhibitory concentration (IC 50) were Cu2+ solution 13.5 μg mL−1, Cu2+-soil 21.4 mg kg−1, penicillin sodium-soil 85.1 mg kg−1, and IC 30 of Pb2+ solution was 60.0 μg mL−1. Detection of pesticide residues in vegetable juices were accomplished in a similar way. The proposed method is fascinating on three points; 1) The generality in the biotoxicity detection depends on toxicants inducing cellular respiratory inhibition; 2) The portability and affordability make it convenient for practical applications, because of replacing incubators and centrifuges; 3) There is potential applicability in less-developed areas due to its simple operation and low-cost. Image 1 • Biotoxicities of multiple environmental pollutants were quantitatively measured and compared by using a μPAD. • Living microorganism E. coli was used as a direct biotoxicity indicator through its respiratory inhibition induced by toxicants. • Detection samples in the form of solution, soil and vegetable juice were all applicable to this μPAD. • The μPAD was fully screen-printed, including carbon three-electrode and all functional units. [ABSTRACT FROM AUTHOR]

Abstract Paper based biosensor devices have the benefit of easy-use, low-cost and environmental friendly for point-of-care diagnostic application. In this research, we report a novel form of paper based biosensor with hierarchical assembled nanomaterials and MOF enhanced bio-probes for the simultaneous detection of microRNA-141 (miR-141) and microRNA-21 (miR-21) which have the potential for early cancer detection. The combination of multi-dimensional nanomaterial allows low impedance and high sensing area on typical poorly defined paper substrate. MOF conjugated bio-probe, methylene blue (MB) and ferrocene (Fc) with distinguishable electrochemical signal, further contributed to the high selectivity and sensitivity. Simultaneously detection of miR-141 and miR-21 with a detection limit of 0.1 fM was demonstrated under optimal conditions. All these features enable accurately target detection in serum samples. Therefore, this strategy is of promising as an inexpensive, easy access diagnosis platform for cancers by means of simultaneously detection of a variety of miRNA biomarkers. Highlights • MoS 2 /AuNPs/AgNW paper-based electrode was used as sensing platform. • Hairpin DNA nanostructures-based biosensor was developed with the detection limit of 0.1 fM. • PtCuMOFs/DNA was used for simultaneous detection miRNA and signal amplification. • The DNA biosensor could be utilized in real serum sample analysis. [ABSTRACT FROM AUTHOR]

Abstract The simultaneous detection of multiple analytes from a single sample is a critical tool for the analysis of real world samples. However, this is challenging to accomplish in the field by current electroanalytical techniques, where tuning assay conditions towards a target analyte often results in poor selectivity and sensitivity for other species in the mixture. In this work, an electrochemical paper-based analytical device (ePAD) capable of performing simultaneous electrochemical experiments in different solution conditions on a single sample was developed for the first time. We refer to the system as a Janus-ePAD after the two-faced Greek god because of the ability of the device to perform electrochemistry on the same sample under differing solution conditions at the same time with a single potentiostat. In a Janus-ePAD, a sample wicks down two channels from a single inlet towards two discreet reagent zones that adjust solution conditions, such as pH, before flow termination in two electrochemical detection zones. These zones feature independent working electrodes and shared reference and counter electrodes, facilitating simultaneous detection of multiple species at each species' optimal solution condition. The device utility and applicability are demonstrated through the simultaneous detection of two biologically relevant species (norepinephrine and serotonin) and a common enzymatic assay product (p-aminophenol) at two different solution pH conditions. Janus-ePADs show great promise as an inexpensive and broadly applicable platform which can reduce the complexity and/or number of steps required in multiplexed analysis, while also operating under the optimized conditions of each species present in a mixture. Graphical abstract Image 1 Highlights • Dual channel, dual working electrode ePAD has been developed and characterized. • Enables detection at two conditions in the same device using the same potentiostat. • Example application showing detection of norepinephrine and serotonin. [ABSTRACT FROM AUTHOR]

Highlights • Paper-based thin sample layer ion transfer voltammetry was realized. • Linear scan voltammetry was chosen to investigate the electrochemical behavior. • Electrochemical behavior are compared to numerical simulation. • Background corrections can be used to eliminate undesired interference. Abstract We report here on paper-supported thin sample layer voltammetry for the determination of ions. To achieve this goal, a simple setup for the coupling of a commercially available electrode to a silver rod electrode was designed and evaluated for paper-supported thin-layer voltammetry. Linear scan ion transfer voltammetry was explored here for ion-selective membranes doped with an ionophore. The ion-transfer processes and electrochemical behaviors of the system are here evaluated and confirmed by numerical simulation. In the proof-of-concept experiments described, the ions tetrabutylammonium chloride (TBA+) and potassium (K+) were studied as model analytes at membranes without and with ionophore, respectively. A linear relationship from 0.1 mM to 1.0 mM K+ was obtained between the charge and ion concentration. The coexistence of background sodium ions did not give appreciable interference, but the background wave was not completely isolated from the analyte wave, as also confirmed by the model. The methodology was successfully demonstrated for determination of K+ in mineral water. It is anticipated that this paper-supported thin-layer detection approach may provide an attractive readout protocol for disposable paper-based analytical devices as the methodology does not place strict demands on reference electrode performance. [ABSTRACT FROM AUTHOR]

Abstract Developing low-cost, portable and simple analysis tools is of vital importance for food safety point-of-care testing. Therefore, herein, a new low-cost, simple to fabricate, disposable, electrochemical mast cell-based paper sensor is proposed and developed to sensitively determine the major milk allergen casein. Then, a graphene (GN)/carbon nanofiber (CN)/ Gelatin methacryloyl (GelMA) composite material with high conductivity and good biocompatibility was modified on the cell-based paper sensor to improve the electrical conductivity and provide a sensing recognition interface for the immobilization of rat basophilic leukemia (RBL-2H3) mast cells. The cyclic voltammetry and differential pulse voltammetry measurement of the mast cells in the paper sensor revealed an irreversible anodic peak, whose peak current is proportional to the number of cells in the range from 1 × 102 to 1 × 108 cells/mL. For the milk allergen detection tests, mast cells exposed to the casein caused a significant reduction in the current signal, displaying an inverse dose-dependent relationship. The developed cell sensor exhibited a range of linearity between 1 × 10−7 and 1 × 10−6 g/mL of casein with a detection limit of 3.2 × 10−8 g/mL and a great reproducibility and selectivity. The electrochemical responses obtained using the cell-based paper sensor were well consistent with the conventional detection assay, with good stability and reproducibility. Therefore, a simple and novel electrochemical method for food allergens detection was developed, demonstrating its potential application in the food safety determination and evaluation. Highlights • An electrochemical cell sensor was first reported based on paper platform. • Carbon nanofiber/graphene/GelMA composite was prepared to fabricate the sensor. • Low detection limit (3.2 × 10−8 g/mL) for casein was achieved using the present sensor. [ABSTRACT FROM AUTHOR]

Abstract The synthesis and employment of volatile toxic compounds as chemical weapons with a large-scale destructive power has introduced a new insidious threat over the last century. In this framework, the development of wearable sensing tools represents a critical point within the security field, in order to provide early alarm systems. Herein, a novel wearable electrochemical biosensor was developed for the rapid and on-site detection of mustard agents. Since a chemical attack is typically carried out by spraying these volatile agents into air, the sensor was designed in order to be able to measure mustard agents directly in the aerosol phase, further than in the liquid phase. The electrodes were screen-printed onto a filter paper support, which allowed to harness the porosity of paper to pre-load all the needed reagents into the cellulose network, and hence to realise an origami-like and reagent-free device. Mustard agent detection was carried out by monitoring their inhibitory effects toward the choline oxidase enzyme, through the amperometric measurement of the enzymatic by-product hydrogen peroxide. A carbon black/Prussian blue nanocomposite was used as a bulk-modifier of the conductive graphite ink constituting the working electrode, allowing for the electrocatalysis of the hydrogen peroxide reduction. After having verified the detecting capability toward a mustard agent simulant, the applicability of the resulting origami-like biosensor was demonstrated for the rapid and real-time detection of real sulfur mustard, obtaining limits of detection equal to 1 mM and 0.019 g·min/m3 for liquid and aerosol phase, respectively. Highlights • Origami paper-based biosensor for sulfur mustard detection. • Rapid detection exploiting choline oxidase reversible inhibition by sulfur mustard. • Sulfur mustard detection in aerosol phase without any operator extra-task. • LOD equal to 1 mM and 0.019 g·min/m3 for liquid and aerosol phase. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A facile palladium functionalized reduced graphene oxide paper was prepared via one-pot co-reduction method. • Evenly-distributed Pd particles show to decorate graphene paper surface and interpose between graphene sheets. • As-prepared freestanding Pd/rGOP can potentially be used as a glucose sensor. Abstract A free-standing palladium/reduced graphene oxide paper (Pd/rGOP) based on one-pot co-reduction was prepared. The as-prepared Pd/rGOPs contain evenly distributed Pd particles interposing between the rGOP layers. The structure and composition of Pd/rGOP were characterized by SEM, EDX, XRD and Raman spectra. We investigated the glucose sensing performance of Pd/rGOP by chronoamperometry, the sensitivity reach as high as 6.70 µA mM−1 cm−2 with the linear range between 0.5 mM and 8 mM. The sensor also exhibits a good anti-interference ability and detection selectivity toward the interference. The proposed sensor has great potential to become a reliable tool in point-of-care medical devices. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel platform of paper-based microfluidic devices for glucose assay from whole blood sample was established that incorporates plasma isolation methods. [•] Dumbbell shaped μPADs was fabricated to obtain the uniform plasma separation and reproducible electrochemical signals. [•] Two pieces of VF2 membranes combined with Whatman No. 1 paper using wax-dipping fabrication method to form a dumbbell shaped μPAD. [•] Conventional Prussian blue-modified screen printed electrode (PB-SPEs) was placed underneath the middle part of a dumbbell shaped μPAD. [Copyright &y& Elsevier]

Mechanically robust graphene papers with both high gravimetric and volumetric capacitances are desired for high-performance energy storages. However, it’s still a challenge to tailor the structure of graphene papers in order to meet this requirement. In this work, a kind of chemical-reduction-tailored mechanically-robust reduced graphene oxide/carbon nanotube hybrid paper has been reported for high-performance electrochemical capacitive energy storages. Gallic acid (GA), as an excellent reducing agent, was used to reduce graphene oxide. Through vacuum filtration of gallic acid reduced graphene oxide (GA-rGO) and carboxylic multiwalled carbon nanotubes (MWCNTs) aqueous suspensions, mechanically robust GA-rGO/MWCNTs hybrid papers were obtained. The resultant hybrid papers showed high gravimetric capacitance of 337.6 F g −1 (0.5 A g −1 ) and volumetric capacitance of 151.2 F cm −3 (0.25 A cm −3 ). In addition, the assembled symmetric device based on the hybrid papers exhibited high gravimetric capacitance of 291.6 F g −1 (0.5 A g −1 ) and volumetric capacitance of 136.6 F cm −3 (0.25 A cm −3 ). Meanwhile, it exhibited excellent rate capability and cycling stability. Above all, this chemical reduction tailoring technique and the resultant high-performance GA-rGO/MWCNTs hybrid papers give an insight for designing high-performance electrodes and hold a great potential in the field of energy storages. [ABSTRACT FROM AUTHOR]

Abstract: Sulfide can be removed from wastewater and recovered as elemental sulfur using an electrochemical process. Recently, we demonstrated this principle of product recovery on synthetic feeds. Here, we present a lab scale electrochemical reactor continuously removing sulfide from the effluent of an anaerobic treatment process operated on paper mill wastewater. The effluent contained 44 ± 7 mg of sulfide-S L−1. Sulfide was reduced to 8 ± 2 mg-S L−1, at a removal rate of 0.845 ± 0.133 kg-S m−3 of total anodic compartment (TAC) d−1. The removed sulfide was recovered (75 ± 4% recovery) as pure concentrated alkaline sulfide/polysulfide solution, from which solid elemental sulfur was obtained. The electrochemical sulfide removal was not affected by different soluble constituents or particulate materials present in the wastewater. However, over time sulfide removal decreased due to biological sulfur reduction using the organics present in the wastewater. Therefore, a periodic switching strategy between anode and cathode was developed. Biofilm formation was avoided as the pH of the cathode solution increased to inhibitory levels during cathodic operation, while still allowing full recovery of the sulfur as end product. [Copyright &y& Elsevier]

Abstract: Biological treatment of pulp and paper industry wastewater is made effective by giving a simple electrochemical pre-treatment. Biodegradability index is found to be improved from 0.11 to 0.46 by a short (6.9min) treatment in mild conditions (current density: 112.9Am−2, pH 7.3). The optimal operating point for maximum biodegradability has been found out using response surface methodology (RSM). It is also noticed that there exists an optimal operating point for maximum biodegradability. The specific energy consumption and current efficiency figures at the optimal condition are also promising. Moreover there is considerable reduction in the pollutant load (COD removal: 55% and color removal: 87%). Performance of the process at this operating point has been validated by running biological treatment. Considerable reduction in the requirement of biological reactor volume can be expected by giving such a simple electrochemical pre-treatment. [Copyright &y& Elsevier]

Toward achieving Li-ion batteries with high energy density, SWCNT/Sn composite paper was electrochemically prepared and the addition effect of formaldehyde (HCHO) and polyethylene glycol (PEG) on Sn electrodeposition morphology was studied. PEG improved the wettability of electroplating bath to enable inhomogeneous Sn embeddedness inside SWCNT paper, and HCHO delivered more nuclear growth. The synergetic effect resulted in a composite paper in which Sn particles with several-hundred nanometer order were distributed. Compared with a commercially-available Cu foil (18 μm-thickness) with 32 mg at 2 cm 2 ( φ 16 mm), the weight of the SWCNT paper (5 mg) is one sixth of that of the Cu foil. The dramatic reduction of the component greatly contributes to the increase in energy density of batteries. [ABSTRACT FROM AUTHOR]

Linen texture (LT) paper functionalized with CuO/Cu 2 O/Ppy composite has been prepared and used separately as an electrode for quantitation of glucose, β-galactosidase, and Escherichia coli ( E. coli ). The low-cost CuO/Cu 2 O/Ppy LT paper is prepared through a two-step process; pyrrole adsorbed on an LT paper reacts with Cu 2+ in the presence of ascorbic acid and fructose to form Cu 2 O/Ppy that then reacts with Cu 2+ in the presence of cetyltrimethylammonium bromide. The CuO/Cu 2 O/Ppy LT paper electrode possessing glucose oxidase-like activity catalyzes the oxidation of glucose, allowing quantitation of glucose down to 0.04 mM. To enhance the mass transfer efficiency and reduce the sample volume, CuO/Cu 2 O/Ppy LT paper microelectrodes with an area of 0.12 cm 2 have been fabricated. By taking the specificity of β-galactosidase for the conversion of lactose to form glucose, the paper microelectrode has been employed for the quantitation of β-galactosidase and of E. coli as low as 0.034 U mL −1 and 120 CFU mL −1 , respectively. In addition, this assay is powerful for screening of activators/inhibitors of β-galactosidase and the antibiotic activities toward E. coli. The inexpensive and stable CuO/Cu 2 O/Ppy LT paper electrode is sensitive for quantitation of glucose, β-galactosidase, and E. coli , as well as for drug screening. [ABSTRACT FROM AUTHOR]

Ultrathin gold films (UTGFs) were fabricated on a nanostructured latex-coated paper substrate by physical vapour deposition (PVD) with the aim to provide low-cost and flexible conductive electrodes in paper-based electronics. Morphological, electric and optical properties of UTGFs were dependent on the deposited film thickness. In addition, UTGFs were functionalized with insulating and hydrophobic 1-octadecanethiol self-assembled monolayer and inkjet-printed conductive and hydrophilic poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT–PSS) layer and their electrochemical properties were examined. Results showed that sufficient mechanical stability and adhesion of UTGFs deposited on latex-coated paper was achieved without the need on any additional adhesive layers, enabling a more robust fabrication process of the electrodes. UTGF electrodes tolerated extensive bending without adverse effects and conductivity comparable to the bulk gold was obtained already with the film thickness of 6 nm. Although not been fabricated with the high-throughput method like printing, a very low material consumption (∼12 μg/cm 2 ) together with a high conductivity (resistivity < 3 × 10 −6 Ω cm) makes the UTGFs electrodes potential candidates low-cost components in flexible electronics. In addition, the excellent stability of the UTGF electrodes in electrochemical experiments enables their application in the development of paper-based electrochemical platforms, e.g. for biosensing purposes. [ABSTRACT FROM AUTHOR]

Abstract: In situ grown carbon nanotubes (CNTs) on carbon paper as an integrated gas diffusion layer (GDL) and catalyst layer (CL) were developed for proton exchange membrane fuel cell (PEMFC) applications. The effect of their structure and morphology on cell performance was investigated under real PEMFC conditions. The in situ grown CNT layers on carbon paper showed a tunable structure under different growth processes. Scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) demonstrated that the CNT layers are able to provide extremely high surface area and porosity to serve as both the GDL and the CL simultaneously. This in situ grown CNT support layer can provide enhanced Pt utilization compared with the carbon black and free-standing CNT support layers. An optimum maximum power density of 670mWcm−2 was obtained from the CNT layer grown under 20cm3 min−1 C2H4 flow with 0.04mgcm−2 Pt sputter-deposited at the cathode. Furthermore, electrochemical impedance spectroscopy (EIS) results confirmed that the in situ grown CNT layer can provide both enhanced charge transfer and mass transport properties for the Pt/CNT-based electrode as an integrated GDL and CL, in comparison with previously reported Pt/CNT-based electrodes with a VXC72R-based GDL and a Pt/CNT-based CL. Therefore, this in situ grown CNT layer shows a great potential for the improvement of electrode structure and configuration for PEMFC applications. [Copyright &y& Elsevier]

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]

Abstract: The reductive removal of haloacetic acids (HAAs) in a three-dimensional electrochemical continuous reactor with Pd-granular activated carbon (Pd-GAC) particles as fixed filler and Pd-modified carbon paper (Pd-C) as cathode was studied in this research. Pd-C electrode was prepared from PdCl2 via electrodeposition onto carbon paper. Pd-GAC particles were prepared by the impregnation of Pd2+ ions onto GAC. Efficient electrocatalytic reduction of HAAs in this reactor was exhibited. Effects of current density, initial HHAs concentration, and hydraulic retention time on the HHAs removal were investigated. Under the current density of 0.3 mA/cm2, HAAs with initial concentration of 120 μg/L were reduced to be less than 60 μg/L with hydraulic retention time of 20 min. Electron transfer and HAAs diffusion both played an important role in controlling the electro-reduction process under the conditions of current density less than 0.6 mA/cm2 with an initial HAAs concentration ranging from 120 to 600 μg/L. However, the HAAs diffusion became the primary rate-limiting step when the current density was higher than 0.6 mA/cm2. The Pd0 and Pd2+ species were detected by X-ray photoelectron spectroscopy. The stability of the electrochemical reactor in the reduction removal of HAAs was also exhibited. [Copyright &y& Elsevier]

Malaria elimination is a major goal to be reached in the next decade. Significant progress were made in the past, and the prevalence decreased in many areas while the positive trend stalled in the last years. The exact number of asymptomatic carriers of Plasmodium parasites is unknown since this population is not detected by conventional diagnosis methods and participate in the maintenance of transmission. Molecular methods to detect low parasitemia are not available at point-of-care in low-income countries of malaria endemic areas. Adaptation of molecular methods such as loop-mediated isothermal amplification of DNA may provide effective tools but it required simplification of DNA detection. Square waves voltammetry, easily imbedded in small device such as cell phone, was largely described for DNA detection but support for reaction was an issue to address. Here we used an efficient functionalization method of paper-based material to facilitate the interactions between isothermal amplification product and methylene blue for easy-to-use DNA detection. The proof-of-concept of qualitative detection of very low parasitemia from malaria infected patients using newly chemically treated paper for square waves voltammetry was obtained with a sensitivity and specificity of 100% and a limit-of-detection of 0.1 parasite. μL−1 corresponding to a parasitemia of 0.000002%. [Display omitted] • Asymptomatic carriers of Plasmodium parasites participate in the maintenance of malaria transmission. • Molecular methods to detect low parasitemia are not available at point-of-care in malaria endemic areas. • Detection of Plasmodium DNA using square waves voltammetry and methylene blue required innovative paper functionalization. • The proof-of-concept of low parasitemia diagnosis using chemically grafted paper for square waves voltammetry was obtained. [ABSTRACT FROM AUTHOR]

We have explored AuNPs (13 nm) both as a catalyst and as a core for synthesizing water-dispersible and highly stable core–shell structural gold@ Prussian blue (Au@PB) nanoparticles (NPs). Systematic characterization by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) disclosed AuNPs coated uniformly by a 5 nm thick PB layer. Au@PB NPs were attached to single-layer graphene oxide (GO) to form Au@PB decorated GO sheets. The resulting hybrid material was filtered layer-by-layer into flexible and free-standing GO paper, which was further converted into conductive reduced GO (RGO)/Au@PB paper via hydrazine vapour reduction. High-resolution TEM images suggested that RGO papers are multiply sandwich-like structures functionalized with core–shell NPs. Resulting sandwich functionalized graphene papers have high conductivity, sufficient flexibility, and robust mechanical strength, which can be cut into free-standing electrodes. Such electrodes, used as non-enzymatic electrochemical sensors, were tested systematically for electrocatalytic sensing of hydrogen peroxide. The high performance was indicated by some of the key parameters, for example the linear H 2 O 2 concentration response range (1–30 μM), the detection limit (100 nM), and the high amperometric sensitivity (5 A cm − 2 M − 1 ). With the advantages of low cost and scalable production capacity, such graphene supported functional papers are of particular interest in the use as flexible disposable sensors. [ABSTRACT FROM AUTHOR]

Paper-based analytical devices (PAD) emerge in the scientific community since 2007 as low-cost, wearable and disposable devices for point-of-care diagnostic due to the widespread availability, long-time knowledge and easy manufacturing of cellulose. Rapidly, electrodes were introduced in PAD for electrochemical measurements. Together with biological components, a new generation of electrochemical biosensors was born. This review aims to take an inventory of existing electrochemical paper-based biosensors and biofuel cells and to identify, at the light of newly acquired data, suitable methodologies and crucial parameters in this field. Paper selection, electrode material, hydrophobization of cellulose, dedicated electrochemical devices and electrode configuration in biosensors and biofuel cells will be discussed. [ABSTRACT FROM AUTHOR]

Polyaniline/attapulgite composites (PANI/ATP) were facilely synthesized via in situ oxidative polymerization of aniline on the surface of ATP. The structure of the resulting composites was characterized by scanning electron microscopy (SEM) and FT-IR spectra. The PANI/ATP was coated on a piece of stiff paperboard to construct a paper electrode, and the electrosorption of Pb(II) was carried out by polarizing the PANI/ATP paper electrode at the potential of –0.3 V. The removal of Pb(II) was mainly attributed to the synergistic effect of physisorption, chemsorption (chelation) and electrostatic interaction, and the effect of electrostatic interaction and chelation is more significant than that of physisorption. Batch experiments were conducted to investigate the effect of applied potential, mass ratio of aniline to ATP, initial concentration, and contact time on the removal of Pb(II). The Freundlich isotherm model fitted the experimental data significantly, and the adsorption kinetics was well described by the pseudo-second-order model. Moreover, electrodesorption experiments were performed to reveal the feasibility for the regeneration of the PANI/ATP paper electrode. All the results indicated that the PANI/ATP could be a promising material for Pb(II) removal. [ABSTRACT FROM AUTHOR]

Herein we utilized the filter paper to physically trap red blood cells (RBC) to observe the breathing process of red blood cells based on the permeability of the filter paper. By integrating double-sided conductive carbon tape as the working electrodes, the device could be applied to monitor electrochemical responses of RBC for up to hundreds of minutes. The differential pulse voltammetry (DPV) peak currents increased under oxygen while decreased under nitrogen, indicating that RBC could take in and release oxygen. Further studies demonstrated that the RBC suspension could more effectively take in oxygen than the solution of hemoglobin and the supernatant of RBC, suggesting the natural advantage of RBC on oxygen transportation. This study implied that simple paper-based analytical devices might be effectively applied in the study of gas-participating reactions and biochemical detections. [ABSTRACT FROM AUTHOR]

A novel electrochemical lab-on-paper cyto-device (ELPCD) was fabricated to demonstrate sensitive and specific cancer cell detection as well as in-situ monitoring of multi-glycans on living cancer cells. In this ELPCD, aptamers modified three-dimensional macroporous Au-paper electrode (Au-PE) was employed as the working electrode for specific and efficient cancer cell capture. Using a sandwich format, sensitive and reproducible cell detection was achieved in this ELPCD on the basis of the electrochemical signal amplification of the Au-PE and the horseradish peroxidase-lectin electrochemical probe. The ELPCD displayed excellent analytical performance for the detection of four K562 cells with a wide linear calibration range from 550 to 2.0×10 7 cells mL −1 . Then, this ELPCD was successfully applied to determine cell-surface multi-glycans in parallel and in-situ monitor multi-glycans expression on living cells in response to drug treatment through in-electrode 3D cell culture. The proposed method provides promising application in decipherment of the glycomic codes as well as clinical diagnosis and treatment in early process of cancer. [ABSTRACT FROM AUTHOR]

Abstract: This article reports a facile microwave-assisted approach to synthesize Pt catalysts on carbon nanotube (CNT)/carbon paper (CP) composite through catalytic chemical vapor deposition. The Pt deposits, with an average size of 3–5 nm were uniformly coated over the surface of oxidized CNTs. The electrochemical activity and stability of the Pt–CNT/CP electrode were investigated in 1 M H2SO4 using cyclic voltammetry (CV) and ac electrochemical impedance spectroscopy. The Pt catalysts showed not only fairly good electrochemical activity (electrochemically active surface area) but also durability after a potential cycling of >1000 cycles. The analysis of ac impedance spectra associated with equivalent circuit revealed that the presence of CNTs significantly reduced both connect and charge transfer resistances, leading to a low equivalent series resistance ˜0.22 Ω. With the aid of CNTs, well-dispersed Pt catalysts enable the reversibly rapid redox kinetic since electron transport efficiently passes through a one-dimensional pathway. Thus, the CNTs do not only serve as carbon support, they also charge transfer media between the Pt catalysts and the gas diffusion layer. The results shed some light on the use of CNT/CP composite, offering a promising tool for evaluating high-performance gas diffusion electrodes. [ABSTRACT FROM AUTHOR]

This study investigated pretreatment and biodegradability of wastewater from a paper recycling plant using the electrochemical peroxidation process in a bench scale reactor. The influence of wastewater pH, H2O2 concentration, current density, and reaction time was evaluated for the removal of COD from the wastewater. The COD of wastewater from paper recycling decreased from the initial level of 4300 mg/L in raw wastewater to 106 mg/L (95.7% removal) in wastewater treated by the electrochemical peroxidation process at optimum pH, H2O2 concentration, current densities of 4, 15 and 5 mA/cm², and a reaction time of 30 min. The optimum ratio of H2O2 (mM) to Fe2+ (mM) was found to be 2. The biodegradability of wastewater increased from an initial level of 0.12 to 0.43 after treatment by the electrochemical peroxidation process under optimum experimental conditions at a reaction time of 30 min. Overall, the electrochemical peroxidation process proved to be an efficient and appropriate technique for COD reduction and enhancement of biodegradability of the industrial effluents containing high concentrations of recalcitrant organic compounds. [ABSTRACT FROM AUTHOR]

Abstract: There is an extensively growing interest in using paper or paper-like substrates for batteries and other energy storage devices. Due to their intrinsic characteristics, paper (or paper-like) batteries show outstanding performance while retaining low cost, multifunctionality, versatility, flexibility and disposability. In this overview, we review recent achievements in paper (or paper-like) batteries as well as their applications. Various types of paper power devices are discussed including electrochemical batteries, biofuel cells, lithium-ion batteries, supercapacitors, and nanogenerators. Further scientific and technological challenges in this field are also discussed. [Copyright &y& Elsevier]

Abstract: Although mitochondria have been used for bio-electrochemistry for over 5 years, little is known about their direct electrochemistry mechanism. This paper focuses on developing a better understanding of the electron transfer mechanism of mitochondria from three different organisms at carbon electrodes. Yeast, potato and bovine mitochondria have been successfully isolated and immobilized onto Toray paper electrodes via vapor deposited silica. Organelle-modified electrodes were first characterized using cyclic voltammetry. Similar electrochemical signals were obtained for all organisms. Direct electron transfer was observed when a metabolite of the Krebs cycle was present in the buffer solution. Control experiments based on the immobilization of two electron carriers contained in mitochondria, cytochrome c and a quinone (coenzyme Q 10), tend to show the electron transfer mechanism to the carbon material comes from the quinone pool of the organelles. As quinones are known to be pH-dependent, we further investigated the response of the electrochemical signal of the three isolated mitochondria and the two electron carriers separately. The half wave potentials obtained from the organelles appeared to be pH-dependent and their variations are comparable to coenzyme Q 10 rather than cytochrome c. Finally, extraction of both the cytochrome c and the quinone pool from intact mitochondria was performed to validate our hypothesis that direct electrochemistry of mitochondria happens via the quinone pool. Electrochemistry of immobilized quinone-depleted mitochondria validated the hypothesis that the mitochondria are communicating with the electrodes through the quinone pool. [Copyright &y& Elsevier]

In this work, using human acute promyelocytic leukemia cells (HL-60) as a model, a novel microfluidic paper-based electrochemical cyto-device (μ-PECD) was fabricated to demonstrate a facile, portable, and disposable approach for cancer cell detection and in situ screening of anticancer drugs in a high-throughput manner. In this μ-PECD, aptamers modified three-dimensional macroporous Au-paper electrode (Au-PE) was fabricated and employed as the working electrode for specific and efficient cancer cell capture as well as for sequential in-electrode 3D cell culture. This Au-PE showed enhanced capture capacity for cancer cells and good biocompatibility for preserving the activity of captured living cells. Sensitive cancer cell detection was achieved in this μ-PECD, which could respond down to four HL-60 cells in 10 μL volume with a wide linear calibration range from 5.0 × 10 2 to 7.5 × 10 7 cells mL −1 and exhibited good stability and reproducibility. Then, in situ anticancer drug screening was successfully implemented in this μ-PECD through monitoring of the apoptotic cancer cells after the in-electrode 3D cell culture with drug-containing culture medium, demonstrating its wide range of potential applications to facilitate effective clinical cancer diagnosis and treatment. [ABSTRACT FROM AUTHOR]

• The electrochemical synthesis of precursor to biologically active C-nucleosides was carried out. • An enzyme based bioelectrocatalysis for the oxidation of d -ribofuranose to d -ribonolactone, precursor of Remdesivir was developed. • The electrochemical oxidation was carried out on laccase immobilized poly-thiophene supported carbon fiber paper. • The screening of the reaction condition and plausible mechanism of the reaction were established. A modified electrode based on laccase immobilized poly-thiophene-3-carboxylic acid supported on carbon fiber paper was developed for the electrocatalytic oxidation of D-ribofuranose to otherwise difficult-to-access D-ribonolactone, a precursor for C-nucleoside based drug like Remdesivir. The electrochemical oxidation of D-ribofuranose was achieved by the TEMPO-mediated electrochemical process. The experimental parameters were optimized and validated using Design of Experiment (DoE) statistical tool indicating the concentration of TEMPO and stirring as important parameters in bulk electrolysis. The mechanism for the electrochemical oxidation of D-ribofuronose followed single electron anodic oxidation of TEMPO mediated by laccase to the corresponding oxoammonium nitrosonium species which was vital for the mediated electrochemical oxidation. The mechanism for the electrochemical oxidation was established using cyclic voltammetry and computational studies. The plausible interactions of laccase enzyme with TEMPO mediator were studied using molecular docking experiments. This facile method was successfully applied for the oxidation of D-ribofuranose to D-ribonolactone. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Porous separator functions to electrically insulate the negative and positive electrodes yet communicate lithium ions between the two electrodes when infiltrated with a liquid electrolyte. The separator must fulfill numerous requirements (e.g. permeability, wettability, and thermal stability) in order to optimize the abuse tolerance and electrochemical performance of a battery. Non-woven mat separators have advantages such as high porosity and heat resistance. However, their applications in lithium ion batteries are very limited as their inadequate pore structures could cause accelerated battery performance degradation and even internal short. This work features the development of thermally stable non-woven composite separators using a low cost paper-making process. The composite separators offer significantly improved thermal dimensional stability and exhibit superior wettability by the liquid electrolyte compared to a conventional polypropylene separator. The open porous structures of the non-woven composite separators also resulted in high effective ionic conductivities. The electrochemical performance of the composite separators was tested in coin cells. Stable cycle performances and improved rate capabilities have been observed for the coin cells with these composite separators. [Copyright &y& Elsevier]

Abstract: Carbon nanotube (CNT)/α-Ni(OH)2 composite paper based on CNT paper was prepared by a facile chemical bath deposition (CBD) method. α-Ni(OH)2 nanosheets were vertically grown on individual CNTs in CNT paper to form hierarchical nanowires. The loading mass of α-Ni(OH)2 in the composite paper could be 66wt%. Thus the composite paper showed much higher specific surface area than that of pristine CNT paper. This novel structure brings the composite paper an electrochemical capacitance high to 1144F/g at the current density of 0.5A/g, and maintains 585F/g at 10A/g. This composite paper could be a promising candidate for the electrodes of high-performance supercapacitors. [Copyright &y& Elsevier]

Abstract: Low cost disposable working electrodes are specifically desired for practical applications of electrochemical detection considering maturity of electrochemical stations and data collection protocols. In this paper double-sided conductive adhesive carbon tape with nanostructure was applied to fabricate disposable working electrodes. Being supported by indium tin oxide glass, the prepared carbon tape electrodes were coated with bismuth film for stripping analysis of heavy metal ions. By integrating the bismuth modified electrodes with paper-based analytical devices, we were able to differentiate Zn, Cd and Pb ions with the sample volume of around 15μL. After the optimization of parameters, including modification of bismuth film and the area of the electrodes, etc., Pb ions could be measured in the linear range from 10 to 500μg/L with the detection limit of 2μg/L. Our experimental results revealed that the disposable modified electrodes could be used to quantify migrated lead from toys with the results agreed well with that using atomic absorption spectrometry. Although bismuth modification and stripping analysis could be influenced by the low conductivity of the carbon tape, the low cost disposable carbon tape electrodes take the advantages of large-scaled produced double-sided carbon tape, including its reproducible nanostructure and scaled-up fabrication process. In addition, the preparation of disposable electrodes avoids time-consuming pretreatment and experienced operation. This study implied that the carbon tape might be an alternative candidate for practical applications of electrochemical detection. [Copyright &y& Elsevier]

A spraying method with lacquer was developed for the fabrication of paper-based devices. A patterned iron mask was initially placed on a filter paper and held tightly attached by a magnetic plate placed on the opposite side. After that, acrylic lacquer was sprayed on the filter paper to create a hydrophobic area while the hydrophilic area was protected with the iron mask. The optimal conditions for the fabrication of this device were studied including lacquer type and particle retention efficiency of filter paper. Gloss spray lacquer and filter paper No. 4 were chosen as optimal lacquer type and particle retention efficiency of filter paper, respectively. To evaluate its efficiency, the paper-based devices were used to determine nickel using electrochemical detection. Cu-enhancer solution was employed to increase sensitivity of nickel determination with the optimal concentration of 4.5ppm. Under the optimal conditions, linear range was observed in the range of 1–50ppm with a coefficient of determination of 0.9971. The limit of detection (LOD) and the limit of quantitation (LOQ) were found to be 0.5 and 1.97ppm, respectively. Moreover, these paper-based devices coupled with electrochemical detection were applied to determine nickel in waste water of a jewelry factory and compared to those obtained with inductively coupled plasma optical emission spectrometry (ICP-OES). The results indicated that there were no significant variations between this proposed method (4.15±0.043ppm) and the ICP-OES method (4.06±0.013ppm). Therefore, this spraying method was found to be an excellent alternative for the fabrication of paper-based devices due to its ease of use, affordability and simplicity. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we demonstrated a novel paper-based mediator-less and compartment-less biofuel cell (BFC) with small size (1.5cm×1.5cm). Ionic liquid functionalized carbon nanotubes (CNTs-IL) nanocomposite was used as support for both stably confining the anodic biocatalyst (i.e., NAD+-dependent glucose dehydrogenase, GDH) for glucose electrooxidation and for facilitating direct electrochemistry of the cathodic biocatalyst (i.e., bilirubin oxidase, BOD) for O2 electroreduction. Such BFC provided a simple approach to fabricate low-cost and portable power devices on small-size paper, which can harvest energy from a wide range of commercial beverages containing glucose (e.g., Nescafe instant coffee, Maidong vitamin water, Watermelon fresh juice, and Minute Maid grape juice). These made the low-cost paper-based biodevice potential for broad energy applications. [Copyright &y& Elsevier]

Abstract: The porous carbon electrode in a fuel cell not only acts as an electrolyte and a catalyst support, but also allows the diffusion of hydrogen fuel through its fine porosity and serves as a current-carrying conductor. A suitable carbon paper electrode is developed and possesses the characteristics of high porosity, permeability and strength along with low electrical resistivity so that it can be effectively used in proton-exchange membrane and phosphoric acid fuel cells. The electrode is prepared through a combination of two important techniques, viz., paper-making technology by first forming a porous chopped carbon fibre preform, and composite technology using a thermosetting resin matrix. The study reveals an interdependence of one parameter on another and how judicious choice of the processing conditions are necessary to achieve the desired characteristics. The current–voltage performance of the electrode in a unit fuel cell matches that of a commercially-available material. [Copyright &y& Elsevier]

A microporous PTFE/carbon sublayer between the carbon paper and the catalyst layer played a crucial role in PEM fuel cells. Such a layer reduced the difference among different carbon paper types made by different manufacturers or by the same manufacturer at different times. When such a sublayer was present, the carbon paper seemed to function merely as a support that provided the mechanical strength for the sublayer. A sublayer was extremely useful if the carbon paper was prone to flooding. Sublayers of different thickness containing 24, 35 and 45% PTFE were tested. A four-cell stack could operate stably at a current density of 145 mA/cm2 using unhumidified air and hydrogen when sublayered carbon paper was employed. [Copyright &y& Elsevier]

Abstract: A simple, low-cost and sensitive origami electrochemical immunoassay-device was developed based on a novel gold nanoparticle modified porous paper working electrode (Au-PWE) for point-of-care testing. Azide-functionalized Au-PWE was prepared by the functionalization of Au-PWE with 1-azidoundecan-11-thiol. Alkyne end-terminated antibody was prepared with 4-pentynoic acid and antibody by the 1-ethyl-3-(3-(dimethylamino) propyl) carbodiimide hydrochloride and N-hydroxysuccinimide activation reaction. Alkyne-antibody was coupled to azido-Au-PWE by click reaction as a recognition element. Nearly monodispersed sphere-like silica-coated ferroferric oxide (Fe3O4@SiO2) nanoparticles were prepared via the reverse microemulsion method. Azide-functionalized Fe3O4@SiO2 was prepared by the functionalization of silica shell with 3-bromopropyltrichlorosilane followed by substitution with sodium azide. Alkyne-functionalized antibody and horse radish peroxidase were coupled to azide-functionalized Fe3O4@SiO2 by click reaction as signal label. Horse radish peroxidase and ferroferric oxide could catalyze the oxidation of thionine in the presence of hydrogen peroxide. After the sandwich immunoreaction, the current was proportional to the logarithm of the Microcystin-LR. The linear regression equation was i(μA)=119.89+46.27log c MC-LR (μg/mL) in the range from 0.01 to 200μg/mL. The limit of detection was 0.004μg/mL. This immunoassay would provide a universal immunoassay method in environmental monitoring and public health. [Copyright &y& Elsevier]