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Baicalin (Bn) is one of the flavonoids with various biological activities, and its accurate determination is of great significance to clinical medicine. The new "MOF-on-MOF" materials have a broad application prospect. ZIF-67 and MIL-101(Fe) are typical metal–organic frame (MOF) materials, which have the advantages of flexible structure, large specific surface area, large porosity, and adjustable pore size. In this paper, a disposable and sensitive Bn electrochemical sensor based on ZIF-67/MIL-101(Fe) composite modified carbon paper (CP) electrode was developed for the first time. The sensing nanomaterials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) was used to evaluate the electrochemical behavior of Bn on different modified electrodes. The results showed that ZIF-67/MIL-101(Fe)/CP exhibited a well-defined redox peak compared with bare CP, ZIF-67/CP, and MIL-101(Fe)/CP, which was attributed to the synergistic effect of ZIF-67 and MIL-101(Fe). Under optimal conditions, the electrochemical sensor was able to quantify Bn in the ranges of 0.01 ~ 3 µM and 3 ~ 6 µM with a detection limit (LOD) as low as 0.009 µM (S/N = 3). In addition, the sensor was successfully used for the quantitative analysis of Bn in Dual yellow oral liquid with reliable results. [ABSTRACT FROM AUTHOR]

This mini‐review summarises and discusses recent findings form the literature on the degradation of carbon‐based electrodes for vanadium redox flow batteries (VRFBs). It becomes evident that the focus of current investigations is on carbon paper, carbon felt and graphite felt electrodes, which is understandable from a practical point of view. However, the structural complexity of these materials often prohibits doubtless attribution of observed performance reduction (or increase) to changes in the electrode materials. Among the discussed major causes for degradation are formation or change of surface functional groups, changes in the carbon sp2/sp3 ratio, intercalation of ions as well as formation of inhibiting adsorbates. In order to gain deeper insight into the changes of carbon electrodes in VRFBs under relevant operation conditions, the authors suggest reducing complexity of the investigated materials and applying in situ‐studies under well‐defined and controllable conditions on model electrodes. These studies then should be extended towards more practical systems and may finally help to reduce degradation phenomena including enhanced overvoltages and thus could improve cycling and energy efficiency as well as long‐term stability of vanadium redox flow batteries. [ABSTRACT FROM AUTHOR]

This report presents an investigation into the use of carbon paper electrodes prepared from chitosan-adhered graphene magnetite nanoparticles for the analysis of Cr(VI). The preparation and storage of carbon paper electrodes is a simple process, and these electrodes are easier to replace than electrodes modified by more conventional methods. The electrochemical detection of Cr(VI) using square wave adsorption cathodic dissolution voltammetry (SWAdCSV) with high selectivity and sensitivity, as well as the optimum conditions for the preparation of the electrodes and the electrode parameters affecting the SWAdCSV signal, were the main points of focus of the investigation. Cr(VI) was detected linearly in the range of 4-40 μg L-1 with a detection limit of 2.84 μg L-1. The electrode output precision, calculated as %RSD, was 7.16% (n = 6), and this was the measurement used for the detection of Cr(VI) in standard and test samples with recoveries between 89% and 114%. The results were consistent with those obtained using the standard UV-Vis spectrophotometric method with a paired t-test at 95% confidence level. [ABSTRACT FROM AUTHOR]

The electrocatalytic oxygen evolution reaction (OER) is an arduous step in water splitting due to its slow reaction rate and large overpotential. Herein, we synthesized glycerate-anion-intercalated nickel–iron glycerates (NiFeGs) using a one-step solvothermal reaction. We designed various NiFeGs by tuning the molar ratio between Ni and Fe to obtain Ni4Fe1G, Ni3Fe1G, Ni3Fe2G, and Ni1Fe1G, which we tested for their OER performance. We initially analyzed the catalytic performance of powder samples immobilized on glassy carbon electrodes using a binder. Ni3Fe2G outperformed the other NiFeG compositions, including NiFe layered double hydroxide (LDH). It exhibited an overpotential of 320 mV at a current density of 10 mA cm–2 in an electrolytic solution of pH 14. We then synthesized carbon paper (CP)-modified Ni3Fe2G as a self-supported electrode (Ni3Fe2G/CP), and it exhibited a high current density (100 mA cm−2) at a low overpotential of 300 mV. The redox peak analysis for the NiFeGs revealed that the initial step of the OER is the formation of γ-NiOOH, which was further confirmed by a post-Raman analysis. We extensively analyzed the catalyst's stability and lifetime, the nature of the active sites, and the role of the Fe content to enhance the OER performance. This work may provide the motivation to study metal-alkoxide-based efficient OER electrocatalysts that can be used for alkaline water electrolyzer applications. [ABSTRACT FROM AUTHOR]

Creatinine is one of the most important biomarkers to detect renal failures. The electrochemical detection of creatinine has been performed using complex enzymatic and non-enzymatic electrode arrays hindering their commercialization. In this work, a new and practical non-enzymatic electrochemical sensor was fabricated depositing copper on carbon paper electrodes by physical vapor deposition (namely Cu/CP). Surface and cross-sectional SEM images demonstrated the deposition of copper over the 3D structure of carbon paper. A thin film was found on the surface, while Cu nanowires with diameters of 180 ± 30 nm were found inside the 3D structure of CP. The thickness of the Cu film on the tubular structures of CP was of 390 ± 40 nm. High-resolution TEM images indicated that the Cu film was integrated by hierarchical structures containing terminal Cu hemispheres of 17.6 ± 2.2 nm. Additionally, interplanar distances from the selected-area electron diffraction pattern demonstrated the presence of Cu0, while Cu2O was also found. Creatinine concentrations in saliva between 16 and 400 µM indicate kidney failure. The Cu/CP electrochemical sensor detected creatinine with linear concentration ranges from 0 to 1000 µM with a r2 = 0.9936. Outstandingly, this sensor presented good reproducibility (RSD = 7.3%), and selectivity to detect creatinine in artificial saliva using interferents like urea, glucose, glycine, ascorbic and uric acids. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) have attracted much interest as an alternative energy conversion technology and as a system for recovering and treating wastewater. MFC is a powerful technique for generating energy from various sources, including natural organic matter and renewable biomass. It has several possible applications, including power generation for many small electronic devices, wastewater treatment, and biosensors. However, the restricted power output of MFCs is the most significant impediment to their widespread use and up-scaling in practical applications. The anode electrode is the most critical component of an MFC, where poor anode electrode performance leads to poor MFC efficiency. Therefore, efforts have been made to modify electrodes to improve their performance. While power density is an essential metric in determining MFC efficiency, other parameters such as Coulombic efficiency, current density, cell voltage, and the removal rate of chemical oxygen demand (COD) should also be considered to evaluate the performance of MFC. This study reviews the most recent electrode modification techniques through anode treatments with metal oxides, conductive polymers, carbon nanotubes, and other chemical compounds as well as through cathode modifications. Different modified MFCs are compared in terms of their power density and the type of bacteria and membrane used. [ABSTRACT FROM AUTHOR]

Waste wood, which has a large amount of cellulose fibers, should be transformed into useful materials for addressing environmental and resource problems. Thus, this study analyzed the application of waste wood as supercapacitor electrode material. First, cellulose fibers were extracted from waste wood and mixed with different contents of graphene nanoplatelets (GnPs) in water. Using a facile filtration method, cellulose papers with GnPs were prepared and converted into carbon papers through carbonization and then to porous activated carbon papers containing GnPs (ACP−GnP) through chemical activation processes. For the morphology of ACP−GnP, activated carbon fibers with abundant pores were formed. The increase in the amount of GnPs attached to the fiber surfaces decreased the number of pores. The Brunauer–Emmett–Teller surface areas and specific capacitance of the ACP−GnP electrodes decreased with an increase in the GnP content. However, the galvanostatic charge–discharge curves of ACPs with higher GnP contents gradually changed into triangular and linear shapes, which are associated with the capacitive performance. For example, ACP with 15 wt% GnP had a low mass transfer resistance and high charge delivery of ions, resulting in the specific capacitance value of 267 Fg−1 owing to micropore and mesopore formation during the activation of carbon paper. [ABSTRACT FROM AUTHOR]

The aim of this investigation is to offer a data-based scheme for predicting electrode wear in resistance spot welding. One of the major factors affecting the mechanical properties of spot welds and the variation in weld quality is electrode wear and alloying. In this study, Rogowski coils and twisted pairs attached to the top and bottom electrodes were used to obtain the welding current and the voltage between the electrodes in the welding process, thereby calculating the dynamic resistance value during the welding process. The electrode tip diameter was obtained from the pressure exerted by the upper and lower electrodes on the carbon paper when the current was cut off and was regarded as an indicator of electrode wear. By continuously welding 0.5 mm thick BH 340 steel plates until the electrode failed, the dynamic resistance signal was recorded in real time. Simultaneously, the electrode diameter after every several welds was also recorded. On this basis, the correlation between electrode tip diameter and dynamic resistance is studied. In order to quantitatively study the mapping relationship between dynamic resistance and electrode wear, 10 characteristic values were extracted from the dynamic resistance, and the stepwise regression method was used to obtain the regression formula between the characteristic values and the electrode tip diameter. Using new data to verify the effectiveness of the regression model, the acquired results display that the maximum error between the predicted value of the electrode tip diameter and the measured value obtained by the regression equation with the interactive quadratic term is 0.3 mm, and the corresponding relative error is 7.69%. When welding with a new pair of electrodes, the maximum absolute error was 0.72 mm, and the relative error of the model prediction is within 20% according to the linear regression model with interaction terms. This indicates that this regression model is barely satisfactory for monitoring electrode condition. [ABSTRACT FROM AUTHOR]

This work investigates the optimization of carbon-based electrodes employed in bio-electrochemical systems (BES) through the deposition of nanostructured layers of poly(3,4-ethylene-dioxy-thiophene) poly(styrene-sulfonate) (PEDOT:PSS) on commercial carbon paper electrodes via ultrasonic spray coating (USC). This innovative application of USC demonstrated that uniform and controlled depositions of PEDOT:PSS can be successfully performed on carbon-based electrodes. To this end, the morphology and spatial uniformity of depositions were verified via scanning electron microscopy and Raman spectroscopy. Electrochemical characterizations of fabricated electrodes demonstrated a more than two-fold increase in the electrochemical active surface area with respect to bare carbon paper. A lab-scale experiment on BES was performed, selecting microbial fuel cells (MFCs) as the reference devices. Devices featuring USC-deposited PEDOT:PSS electrodes showed a three-fold-higher energy recovery with respect to control cells, reaching a maximum value of (13 ± 2) J·m−3. Furthermore, the amount of PEDOT:PSS required to optimize MFCs' performance is in line with values reported in the literature for other deposition methods. In conclusion, this work demonstrates that USC is a promising technique for application in BES. [ABSTRACT FROM AUTHOR]

In this paper, a MnO2 nanowire (MnO2-NW) modified carbon paper electrode (CP) was developed as a novel electrochemical sensor for the sensitive determination of tetrabromobisphenol A (TBBPA). The MnO2 nanowire was prepared by a hydrothermal synthesis method, and the morphology and structure of MnO2 were characterized using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical performance of TBBPA on MnO2-NW/CP was investigated by cyclic voltammetry, and the result confirmed that MnO2-NW/CP exhibited excellent sensitivity for the determination of TBBPA due to the high specific surface area and good electrical conductivity of the nanowire-like MnO2. Moreover, the important electrochemical factors such as pH value, incubation time and modified material proportion were systematically studied to improve the determination sensitivity. The interferences from similar structure compounds on TBBPA have also been investigated. Under the optimal conditions, MnO2-NW/CP displayed a linear range of 70~500 nM for TBBPA with a detection limit of 3.1 nM. This was superior to some electrochemical methods in reference. The work presents a novel and simple method for the determination of TBBPA. [ABSTRACT FROM AUTHOR]

The use of enzyme-based biosensors for the detection and quantification of analytes of interest such as contaminants of emerging concern, including over-the-counter medication, provides an attractive alternative compared to more established techniques. However, their direct application to real environmental matrices is still under investigation due to the various drawbacks in their implementation. Here, we report the development of bioelectrodes using laccase enzymes immobilized onto carbon paper electrodes modified with nanostructured molybdenum disulfide (MoS2). The laccase enzymes were two isoforms (LacI and LacII) produced and purified from the fungus Pycnoporus sanguineus CS43 that is native to Mexico. A commercial purified enzyme from the fungus Trametes versicolor (TvL) was also evaluated to compare their performance. The developed bioelectrodes were used in the biosensing of acetaminophen, a drug widely used to relieve fever and pain, and of which there is recent concern about its effect on the environment after its final disposal. The use of MoS2 as a transducer modifier was evaluated, and it was found that the best detection was achieved using a concentration of 1 mg/mL. Moreover, it was found that the laccase with the best biosensing efficiency was LacII, which achieved an LOD of 0.2 µM and a sensitivity of 0.108 µA/µM cm2 in the buffer matrix. Moreover, the performance of the bioelectrodes in a composite groundwater sample from Northeast Mexico was analyzed, achieving an LOD of 0.5 µM and a sensitivity of 0.015 µA/µM cm2. The LOD values found are among the lowest reported for biosensors based on the use of oxidoreductase enzymes, while the sensitivity is the highest currently reported. [ABSTRACT FROM AUTHOR]

We report a series of structurally relevant copper phenanthroline complexes as pre-catalysts for highly selective electrocatalytic reduction of CO2 to C2 products using inexpensive carbon paper electrodes. The Cu complexes with non-substituted phenanthroline promote the production of ethylene with a high faradaic efficiency of 71.2%, while the one with pyridinium-functionalized ligands is more selective for ethanol. The C2 selectivity can be effectively tuned by increasing the number of coordinated phenanthrolines and remains high at a wide range of potentials. [ABSTRACT FROM AUTHOR]

Thermodynamically favorable selective electrooxidation reactions coupled with hydrogen evolution reaction (HER) is a promising strategy for simultaneous production of value-added chemicals and hydrogen. In this work, a binder-free gold nanoflowers electrode based on carbon paper is prepared and used as anode catalyst, which results in good charge transfer, high stability and superior catalytic activity for electrooxidation of glycerol. We develop an integrated system of glycerol electrooxidation with HER, and the effect of potential on the distribution of anodic electrooxidation products and cathodic hydrogen production are investigated. At 1.0 V, the overall reaction reaches 10 mA cm−2 and the selectivity of glyceric acid (GLA) reaches 97.2%. At 1.2 V, hydrogen production reaches the highest value of 960 μmol L−1 and the anode product consists of a mixture of glyceric acid, glycolic acid (GA) and formic acid (FA). At 1.3 V, the selectivity of FA reaches 87.3%. Operando technique in situ infrared spectroscopy is used to monitor the immediate evolution and study the pathway of controlled glycerol electrooxidation. This work demonstrates carbon paper is a promising substrate material of binder-free electrode applied in thermodynamically favorable electrocatalytic reactions boosting hydrogen evolution. [Display omitted] • A binder-free electrode based on carbon paper is developed. • Hydrogen production is increased by 24 times with the addition of glycerol. • The selectivity of glyceric acid on carbon paper supported gold nanoflowers is 97.2%. • In situ FTIR reveals the pathway for electrooxidation of glycerol. [ABSTRACT FROM AUTHOR]

Despite significant advancements in detecting Cd(II) using nanomaterials-modified sensitive interfaces, most detection methods rely solely on a single electrochemical stripping current to indicate concentration. This approach often overlooks potential inaccuracies caused by interference from coexisting ions. Therefore, establishing multi-dimensional signals that accurately reflect Cd(II) concentration in solution is crucial. In this study, we developed a system integrating concentration, electrochemical stripping current, and laser-induced breakdown spectroscopy (LIBS) characteristic peak intensity through in-situ laser-induced breakdown spectroscopy and electrochemical integrated devices. By simultaneously acquiring multi-dimensional signals to dynamically track the electrochemical deposition and stripping processes, we observed that replacement reactions occur between Cu(II) and Cd(II) on the surface of Ru-doped MoS 2 modified carbon paper electrodes (Ru-MoS 2 /CP). These reactions facilitate the oxidation of Cd(0) to Cd(II) during the stripping process, significantly increasing the currents of Cd(II). Remarkably, the ingenious design of the Ru-MoS 2 sensitive interface allowed for the undisturbed deposition of Cu(II) and Cd(II) during the electrochemical deposition process. Consequently, our in-situ integrated device achieved accurate detection of Cd(II) in complex environments, boasting a detection sensitivity of 8606.5 counts μM⁻1. By coupling multi-dimensional signals from stripping current and LIBS spectra, we revealed the interference process between Cu(II) and Cd(II), providing valuable insights for accurate electrochemical analysis of heavy metal ions in complex water environments. [Display omitted] • Multi-dimensional signals including concentration, stripping current, and laser-induced breakdown spectroscopy. • Multi-dimensional signals collected simultaneously enable dynamic track of deposition and stripping processes. • Replacement reactions occur between Cu(II) and Cd(II) on the surface of Ru doped MoS 2 modified carbon paper electrodes. • Accurate detection of Cd(II) in complex environments through multi-dimensional signals. [ABSTRACT FROM AUTHOR]

• 3D numerical study for elucidating performance of carbon-based electrodes in VRFB. • Graphite felt is the optimal electrode owing to its high electrocatalytic activity. • Graphite felt shows better performance, lower pressure drop, and lower cost. • Multi-layered carbon paper and cloth can match Graphite felt's performance. • It was shown that 5 carbon cloth layers / 9 carbon paper layers match Graphite felt. Electrode materials are critical in determining the performance of Vanadium redox flow batteries (VRFB). This work aims at elucidating the difference between carbon-based electrodes for VRFB. The electrodes considered for the present study are Graphite felt, Carbon felt, Carbon paper, and Carbon cloth. To study the characteristic behavior of different electrode materials, a 3D unit cell numerical model was developed by coupling electrolyte flow and electrochemical reactions and mass transfer module apart from considering the electrode structural and material information such as porosity, permeability, thickness, conductivity, and specific area. The simulation results of this study suggest that the Graphite felt is the optimum choice as an electrode material for VRFB as it offers higher electrocatalytic activity, lower pressure drop, better performance, and lower cost. The study is also extended to a multilayer configuration of Carbon Paper and Carbon Cloth. The performance of multi-layered electrodes by stacking single sheets of Carbon Paper and Carbon Cloth electrodes are matched to meet the performance obtained with the Graphite felt electrode. It has been shown with the help of polarization curve and the pressure drop study that the performance of five layers of carbon cloth and nine layers of carbon paper match the performance of Graphite felt, approximately. The present study provides practical guidance for the design and optimization of VRFB electrodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Modified carbon paper (CP) electrodes have been used for naproxen electrooxidation. • Reduced graphene oxide (RGO) improved Pt nanoparticles (Pt NPs) dispersion on CP. • RGO on CP reduced the size of Pt NPs, contributing to increase the electroactivity. • NaCl containing media accelerated the naproxen kinetics electrooxidation. This research study investigates the electrooxidation of naproxen (NPX), an anti-inflammatory pharmaceutical, on modified carbon paper (CP) electrodes. Electrochemical modification of CP electrodes was accomplished with Pt or reduced graphene oxide (RGO)-Pt coatings, resulting in the production of electroactive electrodes. RGO coatings synthesized by cyclic voltammetry (CV) for 10 scans provided the optimal coverage for the CP electrode surface. The deposition of Pt nanoparticles (Pt NPs) on the electrodes (CP or CP-RGO) by CV produced a good electrode surface coverage with 20 synthesis scans. The voltammetric analysis of the electrodes in 230 mg/L NPX solution showed oxidation peaks around 1.0 to 1.2 V. Moreover, the inclusion of RGO in the coating led to an increase in the current density of these oxidation peaks and a decrease of the electrode electron transfer resistance as measured by electrochemical impedance spectroscopy. The electrolysis of NPX in different electrolytes (Na 2 SO 4 and Na 2 SO 4 /NaCl) was conducted at 1.4 V, and the removal of NPX was analyzed using high-performance liquid chromatography. The CP-RGO-Pt electrode in Na 2 SO 4 /NaCl media showed the fastest NPX degradation kinetics, resulting in a 90 % degradation in only 90 min with low charge consumption (0.07 A·h·L-1). The smaller size of Pt NPs deposited on CP-RGO, as observed by field emission scanning electron microscopy and transmission electron microscopy, contributed to the higher electrochemical response in CV and a faster kinetic degradation of NPX. [ABSTRACT FROM AUTHOR]

A new N,O-rich covalent organic framework (COFDHNDA-BTH) was synthesized by an amine-aldehyde condensation reaction between 2,6-dialdehyde-1,5-dihydroxynaphthalene (DHNDA) and 1,3,5-phenyltriformylhydrazine (BTH) for carbaryl detection. The free NH, OH, and C=O groups of COFDHNDA-BTH not only covalently couples with acetylcholinesterase (AChE) into the pores of COFDHNDA-BTH, but also greatly improves the catalytic activity of AChE in the constrained environment of COFDHNDA-BTH's pore. Under the catalysis of AChE, the acetylthiocholine (ATCl) was decomposed into positively charged thiocholine (TCl), which was captured on the COFDHNDA-BTH modified electrode. The positive charges of TCl can attract anionic probe [Fe(CN)6]3−/4− on the COFDHNDA-BTH-modified electrode to show a good oxidation peak at 0.25 V (versus a saturated calomel electrode). The carbaryl detection can inhibit the activity of AChE, resulting in the decrease in the oxidation peak. Therefore, a turn-off electrochemical carbaryl biosensor based on a flexible carbon paper electrode loaded with COFDHNDA-BTH and AChE was constructed using the oxidation peak of an anionic probe [Fe(CN)6]3−/4− as the detection signal. The detection limit was 0.16 μM (S/N = 3), and the linear range was 0.48~35.0 μM. The sensor has good selectivity, repeatability, and stability, and has a good application prospect in pesticide detection. [ABSTRACT FROM AUTHOR]

The influence of the porous structure on the electrochemical characteristics of supercapacitors with nanocomposite paper electrodes based on carbon nanotubes and resorcinol–formaldehyde xerogel is studied. The porous structure and hydrophilic–hydrophobic properties of electrodes based on the carbon paper were studied by the method of standard contact porosimetry in the range of pore radii from ~1 to 105 nm. The specific surface area ranged from 780 to 960 m2/g. The samples contained both hydrophilic and hydrophobic pores. Cyclic capacitance–voltage curves and impedance spectra in 1 M H2SO4 solution showed practically solely the charging of the electrical double layer without a noticeable effect of the pseudocapacitance from Faraday reactions. When the voltage sweep rate was changed by a factor of 100, the values of the equilibrium specific capacitance changed insignificantly (by a factor of 1.25 to 1.36), which indicates the optimality of the porous structure and the dominant contribution of the electrical double layer capacitance to the total capacitance of the supercapacitor. The dependences of the specific volumetric capacitance of the electrode on the logarithm of the voltage sweep rate have a falling linear character for all studied electrodes. A proportionality between the specific capacitance and the electrode specific surface area is demonstrated. This is due to the high porosity of the electrodes (~80 vol %) and the regularity of their porous structure. In addition, according to estimates, from 87 to 89% of the surface was hydrophilic, i.e., can be attributed to functioning pores; only 13 to 11%, to hydrophobic pores. A very high value of the supercapacitor specific power (45.8 kW/kg) was achieved. This shows that the nanocomposite paper is promising for supercapacitors. [ABSTRACT FROM AUTHOR]

Successful practical implementation of bioelectrochemical systems (BES) requires developing affordable electrode structures that promote efficient electrical communication with microbes. Recent efforts have centered on immobilizing bacteria with organic semiconducting polymers on electrodes via electrochemical methods. This approach creates a fixed biocomposite that takes advantage of the increased electrode's electroactive surface area (EASA). Here, it is demonstrated that a biocomposite comprising the water‐soluble conjugated polyelectrolyte CPE‐K and electrogenic Shewanella oneidensis MR‐1 can self‐assemble with carbon paper electrodes, thereby increasing its biocurrent extraction by ≈6‐fold over control biofilms. A ≈1.5‐fold increment in biocurrent extraction is obtained for the biocomposite on carbon paper relative to the biocurrent extracted from gold‐coated counterparts. Electrochemical characterization revealed that the biocomposite stabilized with the carbon paper more quickly than atop flat gold electrodes. Cross‐sectional images show that the biocomposite infiltrates inhomogeneously into the porous carbon structure. Despite an incomplete penetration, the biocomposite can take advantage of the large EASA of the electrode via long‐range electron transport. These results show that previous success on gold electrode platforms can be improved when using more commercially viable and easily manipulated electrode materials. [ABSTRACT FROM AUTHOR]

A novel electrochemically assisted cycloaddition process is proposed, in which highly efficient coupling of CO2 with styrene oxide (SO) can be achieved to form styrene carbonate (SC) as a high‐value‐added product. A series of Cu catalysts with different morphologies and chemical states were fabricated on carbon paper (CP) by using in‐situ electrodeposition, and the sample with nano‐dendrimer structure was found to exhibit a relatively high activity of 74.8 % SC yield with 92.7 % SO conversion under gentle reaction conditions, thus showing its potential for practical applications. The relatively high electrochemically active surface area and charge transfer ability of dendrimer‐like Cu benefited the electrochemical reaction. In particular, the Cu2+ species that were formed in situ during the reaction played a vital role in enhancing the activity and selectivity of the proposed Cu/CP hybrid catalyst. Cu2+ atoms served as active sites that can not only electrochemically activate CO2 but also facilitate the ring opening of SO. Mechanistic analysis suggested that the reaction followed electrochemical and liquid‐phase heterogeneous paths, which provide a new green and sustainable route for efficient utilization of CO2 resources for fine chemical electrosynthesis. [ABSTRACT FROM AUTHOR]

Zinc‐air batteries (ZABs) have anodic challenges to overcome such as passivation, shape changes, and hydrogen evolution. In this work, zinc anodes were electrosynthesized on carbon paper electrodes using organic additives (Zn/CP) to investigate their viability as an alternative to benchmarked Zn foils. Additionally, the typical aqueous electrolyte (6 M KOH) was replaced by a gel polymer electrolyte (GPE) to assist Zn/CP to decrease anodic issues. In 6 M KOH, the current density of the ZAB with Zn/CP was 42 mA cm−2 @ 0.6 V vs. 28 mA cm−2 for Zn foil. However, chronopotentiometric tests demonstrated that the ZAB with Zn foil possessed a higher stability. SEM images after the stability tests and tests by linear‐sweep voltammetry revealed that Zn/CP suffers a higher formation of hydrogen gas, promoting such morphological changes, decreasing the number of active sites and, thus, stability. The aqueous media was then replaced by the GPE based on polyacrylic acid cross‐linked with potassium (PAAK). Tests revealed that the GPE at different compositions (from 3 to 10 wt.%) significantly decreased the Zn issues, where the GPE at 3 wt.% of PAAK was the most favorable composition, providing comparable current/power densities to the obtained at 6 M KOH (40 vs. 42 mA cm−2 and 25.2 vs. 26.8 mW cm−2). [ABSTRACT FROM AUTHOR]

Carbon nanofoam papers (CNFPs) serve as device-ready negative electrodes for nonaqueous sodium-ion (Na-ion) batteries, with fast and reversible Na+ storage at the aerogel-like, disordered carbon nanofoam. These binder-free, scalable electrode architectures are not only advantageous for the construction of practical, high-performance Na-ion cells, but are also effective platforms to analyze charge-storage mechanisms. We use in situ optical imaging at the outer surfaces of CNFPs in a Na half-cell to track the distinctive color changes that accompany the multi-stage Na+-storage processes on scanning these electrodes through their active voltage window (0–2 V vs Na∣Na+). We observe that electrochromic transitions ― black in the native (unsodiated) state→blue→red/gold ― occur primarily with deep levels of sodiation at <0.5 V vs Na∣Na+. In situ Raman scattering measurements in the same optical cell show that these color changes correlate with shifts in the characteristic G-band Raman peak that would indicate bulk Na+ insertion into nanoscopic graphitic domains within the aerogel-like carbon. The CNFPs also exhibit appreciable Na-ion storage at higher voltage (0.5–2 V vs Na∣Na+), which can be ascribed to surface-based mechanisms that are accompanied by shifts in the D-band Raman peak, but which do not induce appreciable color change [ABSTRACT FROM AUTHOR]

[Display omitted] The design and synthesis of advanced electrodes with high conductivity and flexibility are the key to the development of wearable energy storage devices. Herein, a strategy for preparing conductive carbon paper electrode for flexible supercapacitors is reported by vacuum filtration of a mixture of biomass hierarchical porous carbon materials (HPC), cellulose nanofibers (CNFs) from polysaccharide cellulose of plant origin and silver nanowire (AgNWs), in which CNFs serve as substrates for dispersion and crosslinking of HPC. The prepared self-supporting electrode showed multi-scale pore structure and excellent conductivity (14.1 S cm−1). The electrode exhibited the highest specific capacitance of 383 F g−1 at 0.5 A g−1. Even after 10,000 charge and discharge cycles, 95 % of the original capacitance was remained, which means excellent cyclic stability. High strength and flexibility of the as-assembled flexible supercapacitor make the electrochemical performance of this device remain unchanged when bent at any angle. The present research delineates a simple and convenient method to prepare green, efficient and low-cost flexible supercapacitor. [ABSTRACT FROM AUTHOR]

Paper mulberry fruit juice, as a sugar-based biomass waste product, was used to make porous carbon by hydrothermal treatment and KOH activation as supercapacitor electrodes. Under different hydrothermal conditions, we investigated the response of hydrochars and the performance of porous carbon as an electrode material. The results showed that the hydrochar obtained at low temperatures and a short duration retained more abundant oxygen-containing functional groups, and had a better surface morphology of well-dispersed carbon microspheres, which facilitated its activation. The maximum specific surface area of porous carbon (AHCT 8 C 180) obtained in this study was 3543.8 m2 g−1 under hydrothermal conditions of 180 °C for 8 h. The corresponding porous carbon, as the material of the electrode in the supercapacitor, achieved a good specific capacitance of 428 F g−1 at a current density of 0.5 A g−1. The symmetric supercapacitor fabricated using AHCT 8 C 180 achieved an energy density of 9.56 Wh kg−1 at a power density of 125 W kg−1, In summary, hydrothermal conditions can optimize the specific surface area (S BET) and pore structure of carbon biomass materials through modulating the structure of hydrochar and the construction of the precursor, guiding the preparation of porous carbon used as an electrode material with superior capacitance. [Display omitted] [ABSTRACT FROM AUTHOR]

• Preparation of ZIF-67/PEDOT/CP self-supporting electrodes using simple in situ hydrothermal. • The addition of PEDOT to ZIF-67 helps to achieve high electrical conductivity and large specific surface area. • The sensor has a high detection performance for CGA. • ZIF-67/PEDOT/CP provided a new sensor for the detection of CGA in real sample. The design of efficient electrocatalysts for the determination of chlorogenic acids (CGA) is crucial in the biological and medical fields. In this paper, ZIF-67/poly(3,4-ethylenedioxythiophene) (PEDOT) nanocomposites were synthesised. The introduction of PEDOT increased the electrical conductivity of the ZIF-67/PEDOT composites, inhibited the Co atom agglomeration, led to the exposure of more active sites and increased the transport channels. An ultrasensitive CGA sensor based on ZIF-67/PEDOT nanocomposite modified carbon paper (CP) electrode was developed. The nanomaterials were characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction spectroscopy (XRD). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study the electrochemical properties of the modified CP electrode. In addition, the effects of different experimental conditions such as pH, scan rate and concentration on the peak current of CGA were investigated. Under the optimised conditions, the linear range of ZIF-67/PEDOT/CP for the determination of CGA was 0.1 ∼ 40 μM, and the limit of detection (LOD) was as low as 0.003 μM (S/N = 3). Furthermore, the sensor was successfully used for the quantitative analysis of CGA in real samples. [ABSTRACT FROM AUTHOR]

• Carbon paper electrode shows poor mechanical stability, affecting the AORFB performance. • The mechanical robustness of carbon cloth electrode contributes to a reliable and durable AORFB performance. • Carbon cloth electrode showed high stability when used on quinone oxidation–reduction cycles. • Electrochemical active sites on the carbon cloth increase current densities and AORFB power density. • Carbon cloth electrode provides higher AORFB power density at high electrolyte flow rate. Aqueous organic redox flow batteries (AORFBs) are emerging as promising candidates for efficient energy storage in grid-scale applications. In this study, we present a comprehensive analysis comparing the performance of thermally treated carbon paper and chemically oxidized carbon cloth electrodes, which have been extensively examined for their potential suitability in AORFBs. Results indicate that carbon cloth electrodes exhibit a higher concentration of oxygenated functional groups, contributing to enhanced electrochemical kinetics and improved electrochemical stability. These attributes translate to an AORFB with 62 times higher power density when compared to paper-based electrodes used. Through repeated charge-discharge cycles utilizing the BQDS║AQS model as a representative AORFB prototype, superior performance in the carbon cloth electrodes is consistently observed. Our findings even suggest the potential for optimizing the flow rate of the electrolyte to further enhance performance. [ABSTRACT FROM AUTHOR]

Developing high-efficiency bifunctional materials for electro-catalysis and supercapacitors are urgently needed but challenging. Herein, we develop a self-supporting Co–Ni LDH electrode prepared by in-situ growing ZIF-L(Co)@ZIF-L(Co, Ni) on carbon paper followed by a pseudomorphic transformation. The optimized Co–Ni LDH/carbon paper electrodes (CN-2/CP) exhibit excellent electrochemical activity and stability in oxygen evolution reactions (OER) and supercapacitors. The CN-2/CP electrode displays a low overpotential of 230 mV at 10 mA cm−2 and superior stability at 40-h chronopotentiometry for OER. For supercapacitor, the CN-2/CP electrode delivers a high specific capacitance of 1346 F g−1 at 1 A g−1 and maintains a capacitance of 88.5% after 7000 charge/discharge cycles at 20 A g−1. Based on the physical and chemical characterization results, the high performance originates from the in-situ electrochemical conversion of metal hydroxide, improved conductivity, fast charge transfer at the interface and unique layered cross morphology providing more active sites. [Display omitted] • In-situ synthesis of Co–Ni LDH 3D porous array on carbon paper. • The self-supported electrode exhibits high OER performance and stability. • The large surface area and high porosity of CoNi LDH provide abundant active sites. [ABSTRACT FROM AUTHOR]

Here, polyaniline (PANI) is reported loaded on carbon paper to modify the carbon paper-PANI-Pt electrode surface, tailoring the electrocatalytic capability towards the hydrogen evolution reaction and ethanol oxidation reaction. The reasons for the enhancement by the PANI layer are attributed to the hydrophilic electrode surface, uniform dispersion of Pt, and large electrochemical active surface. [ABSTRACT FROM AUTHOR]

N‐isopropylacrylamide was polymerized on the surface of copper‐plated carbon paper electrode by a novel redox initiation system composed of persulfate and copper nanoparticles, and the PNIPAAm−Cu NPs@CP film electrode was obtained. Cyclic voltammetry (CV) results showed that the electrode exhibits a reversible temperature, pH and glucose switchable electrical signal response through the ferrocene carboxylic acid (Fc(COOH)). With this basis, a 4‐current output logic gate system consisting of 3‐response inputs of temperature, pH, and glucose was fabricated and a corresponding logic circuit for 3‐input/4‐output ports was established. This work might provide a new avenue for the development of multi‐valued biologic systems. [ABSTRACT FROM AUTHOR]

The surface coating of a gas reaction electrode with layered double hydroxides (LDHs) featuring various electrode catalyst activities was prepared via electrodeposition and the subsequent crystal growth of LDHs. LDH formation was confirmed by X-ray diffraction and Raman scattering measurements after subsequent crystal growth on respective electrodeposited precursor films in Ni-Fe and Zn-Al LDH systems. However, the crystal growth of LDHs in Ni-Mn and Cu-Mn systems was observed on the Mg-Al LDH-electrodeposited films. LDH films were also deposited on the surface of a carbon paper electrode with a rugged surface via electrodeposition and subsequent crystal growth. Using the prepared LDH-coated carbon paper electrodes, the electrode catalytic activity for the oxygen reduction reaction (ORR) was examined. For Ni-Mn, Ni-Al and Ni-Fe LDH-coated carbon paper electrodes, the threshold voltages of the ORR decreased. Hence, the LDHs electrodeposited on a gas reaction electrode have high electrochemical catalytic activity for the ORR. [ABSTRACT FROM AUTHOR]

BACKGROUND: Electrosorption efficiency for uranyl ion (UO22+) capture is low in acid solution due to the adverse effect caused by protons. This requires novel electrodes effective at acid conditions for UO22+ electrosorption in highly acidic industrial effluents such as spent nuclear fuel treatment. RESULTS: In the current study, UO22+ electrosorption was conducted using an amidoxime‐modified carbon paper (CP‐AO) electrode. The effects of voltage and frequency, pH, UO22+ initial concentration, and competing ions on UO22+ electrosorption were investigated. The reusability and electrochemical properties of the CP‐AO electrode were studied. The experimental results showed that the current CP‐AO electrode worked well in acidic conditiona (pH = 3) with a square wave periodic voltage (SWPV, −4 V, 1000 Hz), and outperformed a previously used carbon felt‐based electrode. The CP‐AO electrode showed considerable selectivity toward UO22+ in the presence of competitive ions. After seven rounds of continuous electrosorption–desorption, the CP‐AO electrode still showed good UO22+ uptake efficiency. The electrosorption mechanisms were studied in‐depth based on experimental and characterization results. The electrosorption of UO22+ by the CP‐AO electrode was due mainly to the electric field force moving UO22+ to the surface of the electrode, leading to electrodeposition of uranium compounds and the formation of electrically neutral substances. CONCLUSIONS: The results indicated that based on SWPV electrosorption the CP‐AO could be a desirable treatment approach for acidic uranium‐containing wastewater with promising practical applications. [ABSTRACT FROM AUTHOR]

Arsenic contamination is widespread in water bodies and poses a significant risk to human health, thus developing a rapid and inexpensive in situ method for the detection of arsenic is urgently needed. In this study, a chitosan-catechol carbon paper electrode was fabricated by electrodeposition of chitosan on a conductive carbon paper and subsequential electro-oxidative grafting of catechol. This chitosan-catechol modified electrode demonstrated good performance in detecting trace amounts of arsenic, which is mainly due to the significantly amplification of oxidation signals generated by ferrocene (Fc) on chitosan-catechol hydrogel. The interaction of As(III) with quinone and semiquinone radicals results in the decrease of electronic transmission nodes. The modified electrode exhibited a good detection capability of low concentration As(III) with a detection limit 0.82 ppb by differential pulse voltammetry (DPV). In addition, the chitosan-catechol modified sensor has the merits of high reproducibility, durability and strong resistance to ionic interference. Further successful detection of As(III) in actual rice and soil samples suggests its good potential in the field of in situ detection. [Display omitted] • Modified paper sensor was constructed by catechol grafting without gold modification. • The redox of catechol allows a significant amplification of oxdation signals. • Modified paper sensor achieves a LOD of 0.82 ppb for As(III) detection. • Actual rice and soil samples can be analyzed by the modified paper sensors. [ABSTRACT FROM AUTHOR]

Cubic MnxCo3−xO4 (x = 0–0.5) spinel nanocrystal thin films were fabricated on carbon fibre electrodes via one-step topotactic catalysis using Co(OH)2 nanosheets under aqueous and mild reaction conditions (<120 °C). The MnCo3O4 (Mn = 0.01)/CFP catalyst showed the best charge transport efficiency, exhibiting excellent OER activity and stability. [ABSTRACT FROM AUTHOR]

For the electro-reduction of CO 2 to syngas, the fabrication of electrodes with excellent and adjustable catalytic performance is a critical step. In this work, Ni particles encapsulated in N-doped carbon nanotubes on carbon paper (Ni@N-CNTs/CP) composites were designed and prepared via an in-situ chemical vapor deposition method. As confirmed by different characterization techniques, the Ni@N-CNTs are successfully synthesized, and the surface of the CP is evenly covered by the Ni@N-CNTs. The effects of Ni content and treating temperature on the textural properties of composites are carefully investigated. The Ni@N-CNTs/CP composites are directly employed as the electrode for electro-reduction of CO 2 , and the action mechanisms of the N species, Ni particles, and N-CNTs structure are explored as well. The electrode exhibits excellent catalytic activity and high stability, reaching a specific current of 10 mA cm−2. The H 2 /CO ratio in the achieved syngas can be tuned in the range of 5/1 to 1/1.5. Image 1 • A in-situ CVD method was employed to fabricate an electrode for electro-reduction of CO 2. • The as-synthesized Ni@N-CNTs evenly cover on the whole surface of CP. • The Ni@N-CNTs/CP electrode exhibits high CO 2 reduction activity and stability. • The ratio of H 2 /CO can be adjusted in the range of 5/1 to 1/1.5. • The action mechanism of different components are detailedly investigated. [ABSTRACT FROM AUTHOR]

A naturally occurring water‐soluble cobalt‐complex cyanocobalamin (Vitamin B12) has been identified as a new and efficient electrocatalyst for the CO2‐to‐CO reduction reaction in aqueous solution. Heterogeneous B12‐electrocatalysts prepared by a simple electrochemical immobilization technique on graphene‐oxide (GO)‐modified glassy carbon and carbon paper (CP) electrodes, without any non‐degradable polymer‐binders, showed a highly stable and well‐defined surface‐confined redox peak at E'=−0.138 V vs. RHE with a surface‐excess value, ΓB12=4.28 nmol cm−2. This new electrocatalyst exhibits 93 % Faradaic efficiency for CO2‐to‐CO conversion at an electrolysis potential, −0.882 V vs. RHE (an optimal condition) with a high current density, 29.4 mA cm−2 and turn‐over‐frequency value, 5.2 s−1, without any surface‐fouling problem, in 0.5 m KHCO3. In further, it follows an eco‐friendly, sustainable and water‐based approach with the involvement of biodegradable and non‐toxic chemicals/materials like B12, GO and CP. [ABSTRACT FROM AUTHOR]

As an alternative to noble metals, MoS2 has been recognized as promising active and earth abundant electrocatalyst for the hydrogen evolution reaction (HER). Here, we demonstrate novel 2H‐phase MoS2 nanoclusters as efficient electrocatalyst for HER, prepared via hydrothermal process without using additional reducing agents to precursors. The MoS2 nanoclusters coated carbon paper electrode shows Tafel slope of 103 mV dec−1 at voltage sweep rate of 2 mV s−1 for HER with onset potential and over‐potential (η10) of 0.132 and 0.212 V, respectively. The good catalytic performance can be attributed to large accessible electrochemically active surface area and sites along with easy transport of electrolyte due to hydrophilic nature of prepared MoS2 nanoclusters. [ABSTRACT FROM AUTHOR]

Herein, a three-dimensional graphene wall (GWs) and nano-Cu 2 O modified carbon fiber paper (CFP) electrode were used to develop a disposable and sensitive non-enzymatic glucose sensor. This sensing interface of GWs/Cu 2 O consists of an interlaced CFP on which intercrossed graphene walls (GWs) were vertically tethered in situ by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD), and Cu 2 O nanoparticles (NPs) were evenly grew on the 3D GWs layer and skeleton through the complete thermal decomposition of copper acetate (Cu (CH 3 COO) 2) at high temperature. The CFP/GWs/Cu 2 O shows a large specific surface area and rich solution diffusion channels, which can expose more catalytic active sites without Nafion fixation film, thus greatly improving the electrocatalytic performance of this glucose sensor. The CFP/GWs/Cu 2 O sensor shows excellent catalytic performance to glucose with a linear detection range of 0.5 μM–5166 μM, LOD of 0.21 μM, and response time <4 s. This kind of disposable and sensitive electrode can capable of controlling uniform growth and accurate quantification, and has great development potential in the field of medical detection and the commercialization of wearable sensors. Image 1 • A disposable and sensitive non enzyme glucose sensor was developed by using GWs and nano Cu 2 O modified CFP electrode. • The staggered GWs were fixed vertically on the 3-D interlaced CFP by RF-PECVD. • The CFP/GWs/Cu 2 O shows a large specific surface area and rich solution diffusion channels. • Compared with the commercial glucose biosensor, the CFP/GWs/Cu 2 O electrode has excellent catalytic performance. [ABSTRACT FROM AUTHOR]

Intensive attempts have been devoted to solving the inferior cycling stability of Si-based electrode induced by the large volume change of Si. However, the complex synthesis procedures make many strategies much low practical significances. Together with the inferior cycling stability, an easy and scalable fabrication strategy is still a great challenge for implementing Si anode in commercial batteries. This work uses a simple water steam selective etching method to simultaneously engineer the pores and the confinement of commercial Si/SiO x in carbon paper electrodes, leading to a significant improvement in electrode flexibility and cycle life. The as-prepared freestanding lotus-seed-pod-like steam-etched Si/SiO x @CNF electrode shows a high capacity retention of 137% after 1000 cycles at 3 A g−1. It also possesses outstanding electrochemical performance in a flexible lithium-ion full battery with LiCoO 2 /steam-etched CNF as the cathode, even under bended condition. This simple approach may offer a pathway for the application of Si-based anode in commercialization and/or flexible energy storage devices. Image 1 [ABSTRACT FROM AUTHOR]

Redox flow batteries represent a remarkable alternative for grid-scale energy storage. They commonly employ carbon felts or carbon papers, which suffer from low activity towards the redox reactions involved, leading to poor performance. Here we propose the use of electrospun freestanding carbon materials derived from lignin as alternative sustainable electrodes for all-vanadium flow batteries. The lignin-derived carbon electrospun mats exhibited a higher activity towards the VO 2 +/VO2+ reaction than commercial carbon papers when tested in a three-electrode electrochemical cell (or half-cell), which we attribute to the higher surface area and higher amount of oxygen functional groups at the surface. The electrospun carbon electrodes also showed performance comparable to commercial carbon papers, when tested in a full cell configuration. The modification of the surface chemistry with the addition of phosphorous produced different effect in both samples, which needs further investigation. This work demonstrates for the first time the application of sustainably produced electrospun lignin-derived carbon electrodes in a redox flow cell, with comparable performance to commercial materials and establishes the great potential of biomass-derived carbons in energy devices. Image 1 [ABSTRACT FROM AUTHOR]

The regenerative hydrogen/vanadium fuel cell (RHVFC) is investigated with Freudenberg carbon paper electrodes (CPs). Along with thermal treatment, the Freudenberg CPs are also treated with reduced graphene oxide (rGO) using electrophoretic deposition at 300 V. The rGO modified CP results in 25% higher power density than its untreated counterpart under the same operating conditions. In comparison to the first preliminary study, the power density reported herein is more than four times higher. Additionally, the Freudenberg CPs modified with heat treatment followed by rGO deposition facing the membrane (rGOHTFM) provide the best electrolyte discharge utilization (UE) of 99%, followed by untreated (98%) and heat treated samples (97%) at 50 mA cm−2. The rGOHTFM also record high charge and discharge energy efficiencies (η E) of 93% at the same current density, which is slightly higher than untreated CPs (η E = 91%). Cycling the system 10 times also results in higher η E and UE for rGOHTFM CP (η E = 92% and UE = 99% on average) in comparison to untreated electrodes (η E = 86% and UE = 97% on average). In comparison the widely investigated SGL 10AA CP has lower efficiencies and utilization as expected (η E = 74% and UE = 83% on average). Image 1 • Freudenberg carbon paper electrodes are studied in hydrogen/vanadium fuel cell. • Freudenberg electrodes give much better charge/discharge response to SGL 10AA. • Untreated samples have similar performance to rGO modified ones at 50 mA cm−2. • Reduced graphene oxide modification of heat treated samples gave best results. • High cycling efficiencies (92%) and electrolyte utilization (99%) are reported. [ABSTRACT FROM AUTHOR]

Abstract A stable and reproducible layer of Prussian blue (PB) modified with copper was electrodeposited on carbon paper electrodes for the multiple detection of ester flavorants with a bienzymatic biosensor. Carbon fiber composite paper was investigated as high-surface, low-cost substrate for biosensor development. The pre-activation of the electrode surface by cyclic voltammetry was necessary to improve the electrochemical properties before the electrochemical deposition of Prussian blue-copper film (PB-Cu). The stability and the reproducibility of the obtained PB-Cu carbon paper electrode was demonstrated at pH 7.4, optimum for biosensor development. The developed biosensor is based on the immobilization of two enzymes (carboxyl esterase and alcohol oxidase) by cross-linking with glutaraldehyde onto PB-Cu carbon paper electrode. A mixture of key aroma ester compounds (methyl butyrate, ethyl butyrate, methyl cinnamate and ethyl cinnamate) was detected in several food samples with low interferences. Graphical abstract fx1 Highlights • Prussian blue (PB) modified with copper with improved stability at neutral pH. • Carbon fiber composite paper is a high-surface, low-cost substrates excellent for biosensor manufacturing. • Total content of ester flavorants mixtures in foods detection. • Bienzymatic biosensor based on carboxyl esterase and alcohol oxidase. [ABSTRACT FROM AUTHOR]

Summary: Porous conducting carbon fiber‐based composite paper is used as an electrode backing in the fuel cell assembly. It not only acts as a channel through which the reactant and product gases pass to and from the bipolar plate and the catalyst site but also helps in the flow of electrons. In order to perform its role efficiently, it should have sufficient strength, high electrical conductivity, and ideal porous structure. Carbon paper has been fabricated, which builds up the required composite properties. Studies have been conducted to optimize the fiber/matrix ratio in the carbon paper, while ensuring the perfect combination of porosity, mechanical strength, and electrical conductivity for an electrode in a proton electrolyte membrane fuel cells. Detail physico‐mechanical and electrochemical characterizations further ascertain that the fiber/matrix ratio plays an important role in tuning the composite properties. The polarization curve of the unit proton exchange membrane (PEM) fuel cell (with an effective electrode area 4 cm2) shows a peak power density of 916 mW/cm2 for the sample with fiber/matrix ratio of 65:35, which is almost the same as the commercially available sigracet gas diffusion layer (SGL) carbon paper tested under similar conditions. Further, proportionally enlarging the electrode area to 100 cm2 shows that the carbon paper not only shows almost repeatable results in a given set up but also scales up. [ABSTRACT FROM AUTHOR]

• TiO 2 -20PANI/CP greatly improved power output of MFCs. • TiO 2 -20PANI/CP kept bio-affinity and enhanced electrochemical activities. • TiO 2 -20PANI/CP had larger transient charge storage capacity. • PANI modified TiO 2 -NSs enhanced bioelectricity generation. Composite materials can achieve synergistic effect through complementarity components, which are important for improving electrode performance. The co-modification of vertically oriented TiO 2 nanosheets (TiO 2 -NSs) and conductive polyaniline (PANI) are studied. PANI with different content is deposited onto TiO 2 -NSs/CP during electrochemical cyclic voltammetry (CV) with 5, 10, 15, 20 and 25 cycles. Bio-electrochemical experiments indicate that TiO 2 -20PANI/CP electrode with deposited PANI via 20 cycles of CV had the lowest charge transfer resistance (R ct) and the largest transient charge storage capacity (TCSC), which exhibit the best performance. The maximum output power density of PV-4 at TiO 2 -20PANI/CP anode (813 mW·m−2) is increased 63.6% more than that at TiO 2 -NSs/CP anode. The results give a guideline for designing high performance bio-electrode. Moreover, the method is simply and efficient, and could be extended to other nano-semiconductor modified electrodes for superior MFC anodes. [ABSTRACT FROM AUTHOR]

Abstract Understanding the role of defects is important due to its influence on electrical and optical properties of SnO 2. This study reports the role of oxygen defects in SnO 2 quantum dots decorated in carbon paper for an improved electron transfer process in electrochemical applications. A simple and cost-effective chemical route for preparation of a SnO 2 -decorated carbon paper electrode is described. The pseudo-capacitance property of SnO 2 nano-materials allowed strong improvement in capacitance value compared to pristine carbon paper. Transmission electron microscopy, Raman and photoluminescence studies reveal the presence of ultra-small SnO 2 nanoparticles with defects related to prevalent oxygen vacancies. Electron paramagnetic resonance measurement indicates presence of singly charged defect in diamagnetic SnO 2. Temperature-dependent photoluminescence, vibrational studies and electron energy loss spectroscopy provide further evidence for shallow in-plane oxygen defects in the SnO 2 quantum dots, while impedance measurement discloses their significance in the electrochemical hybrid structure. Highlights • Cost-effective synthesis of SnO 2 QDs for making hybrid capacitors. • Surface-enhanced Raman spectroscopy and TEM confirmed retention of SnO 2 QD properties. • Elucidated the significance of in-plane oxygen defects in the performance of hybrid capacitors. • Observed enhanced charge transfer in SnO 2 -QD-decorated carbon electrodes by impedance spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract With the legalization of recreational cannabis use, there is a need to develop a rapid and accurate roadside test that can be used to analyze human saliva samples for Δ9-tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis. Here we demonstrate a novel drug detection method where THC is infused into carbon paper electrodes followed by electrochemical detection in a pH 10 aqueous solution. This method produces a linear, sensitive (down to ∼ 1 pmol), dose-dependent change in the oxidation peak current that varies with THC surface densities. These results, as well as the peak charge per real carbon surface area and linear current/scan-rate dependence, support a model for the distribution of THC on the carbon surface in a thin-layer configuration, facilitating the oxidation of the deposited drug. We also demonstrate electro-oxidation of the two major metabolites of THC, the psychoactive 11-hydroxy-tetrahydrocannabinol (OH-THC), and the non-psychoactive 11-nor-9-carboxy-tetrahydrocannabinol (COOH-THC), that also produce linear, dose-dependent changes in peak charge. However, COOH-THC exhibits a much lower Faradaic efficiency than OH-THC and THC, suggesting that variations in the THC functional groups affect the electro-oxidation of the cannabinoids. Overall, this work illustrates a novel, reproducible, and sensitive method for the analysis of THC and oxidation properties of its common metabolites that could be adapted for use with human saliva samples in future work. [ABSTRACT FROM AUTHOR]

Abstract Developing cost-effective and environmental-friend electrode material is critical to accelerate the large-scale commercialization of the all-vanadium redox flow batteries. Herein, we propose and develop a twin-cocoon-derived self-standing carbon material by a green and safe preparation method. This facile degumming and carbonization process allows the twin-cocoon-derived monolithic carbon material to be decorated with nitrogen defects and oxygen functional groups. It has been demonstrated that this nitrogen-oxygen-rich monolithic carbon electrode material yields a promoted electrochemical activity for both V2+/V3+ and VO2+/VO 2 + couples, causing a 50% decrease in redox potential difference and a 192% increase in diffusion slope as compared with the commercial carbon paper, thereby improving the electrochemical reversibility and enhancing the mass transfer kinetics. It is also found that the flow battery using nitrogen-oxygen-rich monolithic carbon electrode material shows 83% higher average discharge capacity and 20% higher energy efficiency than that with carbon paper at the current density of 100 mA cm−2, promising a high-performance and low-cost all-vanadium redox flow battery. This work opens a new way to developing monolithic carbon electrode material that possesses great potential applications in flow battery and other electrochemical energy conversion and storage systems. Graphical abstract Image 1 Highlights • Twin-cocoon-derived self-standing monolithic carbon catalyst material was proposed. • Nitrogen-doped monolithic carbon contains oxygen-rich functional groups. • NO-MC carbon catalyst material promises a high-performance and low-cost VRFB. • NO-MC carbon catalyst material yields a 50% decrease in redox potential difference. [ABSTRACT FROM AUTHOR]

• A bottom-to-up strategy is adopted to design, fabricate and test the electrode. • Increasing O-functional groups enhances the numbers and activity of active sites. • All the experimental results are consistent with the computational predictions. • The battery delivers an EE of 80.1% and EU of 69.8% at 320 mA cm−2. • The high-performance is related to the good transport properties of carbon cloth. In this work, a bottom-to-up strategy is adopted to design, fabricate and test a uniformly distributed bismuth nanoparticle-modified carbon cloth electrode for vanadium redox flow batteries (VRFBs). The first-principles study reveals that increasing the number of oxygen-functional groups on the surface of carbon fibers can promote the uniform distribution of electrodeposited bismuth nanoparticles, which increases the effective surface areas and active sites. Results also show that the oxygen-functional groups and bismuth exhibit a synergistically catalytic effect, which enhances the kinetics of redox reactions. Therefore, carbon cloth substrate with a high content of oxygen-functional groups is fabricated and tested. The material and electrochemical characterizations, including scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), verify the predictions of the first-principles study. Battery tests show that the VRFBs with the prepared electrode enables an energy efficiency of 88.4% at 160 mA cm−2, 19.6% higher than that with the original electrode. Additionally, the battery is capable of delivering an energy efficiency of 80.1% at a high current density of 320 mA cm−2, which are among the highest performances in the open literature. Finally, it is also proved that the prepared bismuth nanoparticle-modified carbon cloth electrode outperforms the bismuth nanoparticle-modified carbon paper electrode, ascribed to the excellent ion/mass transport properties of carbon cloth. [ABSTRACT FROM AUTHOR]