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To optimize the imbalance between the interfacial bonding and porosity properties of carbon paper (CP) caused by phenol formaldehyde resin (PF) impregnation, and therefore improve the performance of proton exchange membrane fuel cells (PEMFCs), a new approach through cellulose nanofibers grafted with methyl methacrylate (CNFM) as a modified reinforcement and pore-forming agent for PF is investigated. Through suppressing the methylene backbone fracture of CNFM-modified PF during its thermal depolymerization, the interfacial bonding between PF matrix carbon and carbon fibers is enhanced. Compared with unmodified CP, the in-plane resistivity of CNFM-modified CP is reduced by 35.78 %, while the connected porosity increases to 82.26 %, and more homogeneous pore size distribution (PSD) in the range of 20-40 μm is obtained for CNFM-modified CP. Besides, the tensile strength, flexural strength, and air permeability of CNFM-modified CP increase by 72.78 %, 298.4 %, and 103.97 %, respectively. In addition, CNFM-modified CP achieves the peak power density of PEMFCs to 701.81 mW·cm -2 , exhibiting 10.98 % improvement compared with commercial CP (632.39 mW·cm -2 ), evidently achieving an integral promotion of CP and comprehensive performance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Herein, an ultrasensitive electrochemical biosensor for microRNA-155 (miR-155) detection based on the powerful catalytic and continuous walking signal amplification capability of 3D DNAzyme walker and the gold nanoparticles/graphene aerogels carbon fiber paper-based (AuNPs/GAs/CFP) flexible sensing electrode with excellent electrochemical performance was successfully constructed. In a proof-of-concept experiment, in the presence of miR-155, the DNAzyme strands anchored on the streptavidin-modified magnetic beads (MBs) silenced by locked strands can be activated, thus generating the walking arm of the 3D DNAzyme walker. Meanwhile, the substrate strands modified with Fe-MOF-NH 2 nanoparticles were evenly distributed on the surface of MBs and served as tracks of the 3D DNAzyme walker. Once the DNAzyme strand was activated, the catalytic site in the substrate strand can be cleaved in the presence of Mn 2+ , and a large number of stumps modified with Fe-MOF-NH 2 nanoparticles (output@Fe-MOF-NH 2 ) will be generated during the continuous and efficient walking cleavage of the DNAzyme walker, driving the recognition-catalysis-release cycle process for signal amplification. Immediately afterwards, the signal was read out through the base complementary pairing of capture probe (PS) immobilized on the surface of the paper-based flexible sensing electrode AuNPs/GAs/CFP and signal probes output@Fe-MOF-NH 2 , thus achieving the quantitative detection of miR-155. Under optimal experimental conditions, the designed 3D DNAzyme walker-based biosensor exhibited a relatively lower limit of detection (LOD) of 56.23 aM, with a linear range of 100 aM to 100 nM. Overall, the proposed 3D DNAzyme walker biosensor exhibited good interference and reproducibility, demonstrating a promising future in the field of clinical disease diagnosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Lithium sulfur batteries are suitable for drones due to their high gravimetric energy density (2600 Wh/kg of sulfur). However, on the cathode side, high specific capacity with high sulfur loading (high areal capacity) is challenging due to the poor conductivity of sulfur. Shuttling of Li-sulfide species between the sulfur cathode and lithium anode also limits specific capacity. Sulfur-carbon composite active materials with encapsulated sulfur address both issues but require expensive processing and have low sulfur content with limited areal capacity. Proper encapsulation of sulfur in carbonaceous structures along with active additives in solution may largely mitigate shuttling, resulting in cells with improved energy density at relatively low cost. Here, composite current collectors, selected binders, and carbonaceous matrices impregnated with an active mass were used to award stable sulfur cathodes with high areal specific capacity. All three components are necessary to reach a high sulfur loading of 3.8 mg/cm 2 with a specific/areal capacity of 805 mAh/g/2.2 mAh/cm 2 . Good adhesion between the carbon-coated Al foil current collectors and the composite sulfur impregnated carbon matrices is mandatory for stable electrodes. Swelling of the binders influenced cycling retention as electroconductivity dominated the cycling performance of the Li-S cells comprising cathodes with high sulfur loading. Composite electrodes based on carbonaceous matrices in which sulfur is impregnated at high specific loading and non-swelling binders that maintain the integrated structure of the composite electrodes are important for strong performance. This basic design can be mass produced and optimized to yield practical devices.

The increase in anthropogenic pollution raises serious concerns regarding contamination of water bodies and aquatic species with potential implications on human health. Pharmaceutical compounds are a type of contaminants of emerging concern that are increasingly consumed and, thus, being frequently found in the aquatic environment. In this sense, an electrochemical sensor based on an unmodified and untreated carbon fiber paper (CPS-carbon paper sensor) was simply employed for the analysis of trimethoprim antibiotic in fish samples. First, the analytical conditions were thoroughly optimized in order for the CPS to achieve maximum performance in trimethoprim determination. Therefore, an electrolyte (0.1 M Britton-Robinson buffer) pH of 7 was selected and for square wave voltammetry parameters, optimum values of amplitude, frequency and step potential corresponded to 0.02 V, 50 Hz, and 0.015 V, respectively, whereas the deposition of analyte occurred at +0.7 V for 60 s. In these optimum conditions, the obtained liner range (0.05 to 2 µM), sensitivity (48.8 µA µM -1 cm -2 ), and LOD (0.065 µM) competes favorably with the commonly used GCE-based sensors or BDD electrodes that employ nanostructuration or are more expensive. The CPS was then applied for trimethoprim determination in fish samples after employing a solid phase extraction procedure based on QuEChERS salts, resulting in recoveries of 105.9 ± 1.8% by the standard addition method.

A portable device is conducive to the on-site detection of heavy metal ions at trace level in food and the prevention of related food safety issues. In this work, an electrochemical device stacked up with flat electrodes was developed for the detection of Pb 2+ and Cd 2+ . The top layer of the device is a carbon paper as working electrode, which is modified with amino functionalized cobalt-based metal-organic framework and gold nanoparticles. The bottom layer was constructed with the carbon counter electrode and Ag/AgCl reference electrode, and a punched sample cell (Φ = 8 mm) was in the middle. The proposed method could simultaneously determinate Pb 2+ and Cd 2+ via anodic stripping voltammetry with the detection limit of 7.0 × 10 -2 ng mL -1 and 1.1 × 10 -2 ng mL -1 , and was applied in real food samples (drinking water, juice, tea, grain, fruits, vegetables, liver and aquatic products) with the recovery of 91.2-105.4 % and 90.2-111.2 %, respectively., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The remarkable features of a carbon fiber paper sensor (CP) were employed for detection of the estrogenic hormone 17α-ethinylestradiol (EE2), considered a contaminant of emerging concern due to its potential ecotoxicity and widespread in the aquatic ecosystems. In this work, an unpreceded CP pre-treatment study was conducted with the (Il)-hexacyanoferrate(III) ion pair, however a bare sensor without pre-treatment revealed higher efficiency on the oxidation of EE2 compared to a chemical and electrochemical pre-treated CP and a gold nanoparticles modified CP, being thus selected for EE2 determinations. The analytical conditions were thoroughly optimized in terms of electrolyte pH (pH 7), differential pulse voltammetry parameters (modulation time 0.003 s, amplitude 0.09 V, interval time 0.1 s and step potential 0.01 V), and analyte preconcentration potential (0.4 V) and time (180 s). The hormone can be determined by the CP in a wide linear range from 0.1 to 1000 nM, achieving a detection limit of 0.14 ± 0.005 nM and an outstanding sensitivity of 1636 ± 232 μA μM -1  cm -2 in the lowest linear zone (0.1-1 nM). The sensor was validated in river water and fish reaching good recoveries (91.2 ± 4.6 to 109.0 ± 7.1%), reproducibility and repeatability. Moreover, the sensor showed high selectivity to EE2 in the presence of several potential interfering compounds and frequently prescribed drugs, though it could not discriminate the similar hormone, 17β-estradiol, being the total concentration obtained in this case. CP-based sensors emerge as efficient electroanalytical tools, suggesting that modification of the surface may not always be beneficial in terms of sensitivity., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

The paper describes the development of an electrochemical sensor to be used for the determination of synthetic food colorants such as Sunset Yellow FCF (SY) and Tartrazine (TZ). The sensor is a carbon paper (CP) electrode, manufactured by using hot lamination technology and volume modified with fine-grained graphite powder (GrP). The sensor (GrP/CP) was characterized by scanning electron microscopy, energy dispersive spectrometry, electrochemical impedance analysis, cyclic, linear sweep and differential pulse voltammetry. The mechanism of SY and TZ electrochemical oxidation on GrP/CP was studied. The developed sensor has good electron transfer characteristics and low electron resistance, high sensitivity and selectivity. Applying the differential pulse mode, linear dynamic ranges of 0.005-1.0 μM and 0.02-7.5 μM with limits of detection of 0.78 nM and 8.2 nM for SY and TZ, respectively, were obtained. The sensor was used to detect SY and TZ in non-alcoholic and alcoholic drinks. The results obtained from drink analysis prove good reproducibility (RSD ≤ 0.072) and accuracy (recovery 96-104%).

The paper describes the development of a carbon veil-based electrode (CVE) for determining uric acid (UA) in saliva. The electrode was manufactured by lamination technology, electrochemically activated and used as a highly sensitive voltammetric sensor (CVE act ). Potentiostatic polarization of the electrode at 2.0 V in H 2 SO 4 solution resulted in a higher number of oxygen and nitrogen-containing groups on the electrode surface; lower charge transfer resistance; a 1.5 times increase in the effective surface area and a decrease in the UA oxidation potential by over 0.4 V, compared with the non-activated CVE, which was confirmed by energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, chronoamperometry and linear sweep voltammetry. The developed sensor is characterized by a low detection limit of 0.05 µM and a wide linear range (0.09-700 µM). The results suggest that the sensor has perspective applications for quick determination of UA in artificial and human saliva. RSD does not exceed 3.9%, and recovery is 96-105%. UA makes a significant contribution to the antioxidant activity (AOA) of saliva (≈60%). In addition to its high analytical characteristics, the important advantages of the proposed CVE act are the simple, scalable, and cost-effective manufacturing technology and the absence of additional complex and time-consuming modification operations.

In the present work, the exceptional electrochemical properties of carbon paper were characterized and explored in the development of a sensor for the anti-inflammatory drug, ketoprofen. An initial electrochemical characterization of the carbon paper with a redox indicator revealed much higher voltammetric peaks in comparison with other carbon-based electrodes, namely, screen-printed carbon electrode, boron-doped diamond electrode, glassy carbon electrode, pyrolytic graphite electrode, and pencil graphite electrode, predicting a good sensing performance. Ketoprofen showed a pronounced cathodic peak around -1.1 V vs Ag/AgCl (KCl, 3 M) at pH 5 in Britton-Robinson buffer, presenting a diffusion-controlled process. An optimized differential pulse voltammetry procedure was employed for ketoprofen determination achieving a limit of detection of 0.11 ± 0.01 μM, a linearity up to 6.02 μM, and a high sensitivity of 24 ± 4 or 35 ± 3 μA μM -1  cm -2 (depending on the calibration range: 0.088-1.96 μM or 1.96-6.02 μM, respectively) with acceptable (6-15% relative standard deviation) reproducibility and repeatability considering the challenging conditions of its detection in aqueous solutions. The sensor revealed to be highly selective in the presence of common interferents and other widely consumed anti-inflammatory drugs. Moreover, the developed sensor reached good accuracy in wastewater and fish samples with recoveries varying from 82.3 ± 4.4 to 88.6 ± 4.5%., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Pt-SnO 2 @C-ordered flake array was developed on carbon paper (CP) as an integrated cathode for proton exchange membrane fuel cell through a facile hydrothermal method. In the integrated cathode, Pt nanoparticles were deposited uniformly with a small particle size on the SnO 2 @C/CP support. Electrochemical impedance spectroscopy analysis revealed lower impedance in a potential range of 0.3-0.5 V for the ordered electrode structure. An electrochemically active surface area and oxygen reduction peak potential determined by cyclic voltammetry measurement verified the synergistic effect between Pt and SnO 2 , which enhanced the electrochemical catalytic activity. Besides, compared with the commercial carbon-supported Pt catalyst, the as-developed SnO 2 @C/CP-supported Pt catalyst demonstrated better stability, most likely due to the positive interaction between SnO 2 and the carbon coating layer.

Aggregation of reduced graphene oxide (RGO) due to π-π stacking is a recurrent problem in graphene-based electrochemistry, decreasing the effective working area and therefore the performance of the RGO electrodes. Dispersing RGO on three-dimensional (3D) carbon paper electrodes is one strategy towards overcoming this challenge, with partial relief aggregation. In this report, we describe the grafting of negatively charged 4-aminobenzoic acid (4-ABA) onto a graphene functionalized carbon paper electrode surface. 4-ABA functionalization induces separation of the RGO layers, at the same time leading to favorable orientation of the blue multi-copper enzyme Myrothecium verrucaria bilirubin oxidase (MvBOD) for direct electron transfer (DET) in the dioxygen reduction reaction (ORR) at neutral pH. Simultaneous electroreduction of graphene oxide to RGO and covalent attachment of 4-ABA are achieved by applying alternating cathodic and anodic electrochemical potential pulses, leading to a high catalytic current density (Δj cat :193 ± 4 μA cm -2 ) under static conditions. Electrochemically grafted 4-ABA not only leads to a favorable orientation of BOD as validated by fitting a kinetic model to the electrocatalytic data, but also acts to alleviate RGO aggregation as disclosed by scanning electron microscopy, most likely due to the electrostatic repulsion between 4-ABA-grafted graphene layers. With a half-lifetime of 55 h, the bioelectrode also shows the highest operational stability for DET-type MvBOD-based bioelectrodes reported to date. The bioelectrode was finally shown to work well as a biocathode of a membrane-less glucose/O 2 enzymatic biofuel cell with a maximum power density of 22 μW cm -2 and an open circuit voltage of 0.51 V., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The research in electrochemical reduction of CO 2 is shifting towards the discovery of new and novel materials. This study shows a new class of material, that of Ge-S-In chalcogenide glass, to be active for reduction of CO 2 in aqueous solutions. Experiments were conducted with bulk and particle form of the material, yielding different product for each structural form. Faradaic efficiency of upto 15% was observed in bulk form for CO production while formic acid with up to 26.1 % faradaic efficiency was measured in powder form. Chalcogenide studies have focused primarily on the photoelectrochemical reduction however these results provide a strong merit for introducing metal in chalcogenide glass structures for electrochemical reduction of CO 2 . The activity for CO 2 reduction and the change in product selectivity reflects that further efforts to improve the glass structures can be undertaken in order to increase the faradaic efficiency and selectivity of the products., (© 2020 Published by Elsevier Ltd.)

Current collectors are an important component of electrodes, functioning as conductive media by collecting currents from active materials and then exporting them to the external circuit. Common current collectors for graphene hydrogel (GH)-based supercapacitors are nickel foams or metal foils (platinum, gold, and aluminium, etc.). Here, hydrothermally synthesized GH was directly pressed on carbon paper and used as electrodes (denoted as GHE) for supercapacitors. With a mass loading of 2.7 mg·cm -2 at an active area of 0.64 cm 2 , the GHE-based supercapacitors revealed a high gravimetric capacitance of 294 F·g -1 at a current density of 1.18 A·g -1 . When increasing the current density to 28.24 A·g -1 , 66% (193 F·g -1 ) of the initial capacitance was maintained for the GHE-based supercapacitors. High performance for GHE-based supercapacitors was attributed to large specific surface area and good electrical conductivity of GH, and its intimate contact with carbon paper.

Ultra-high exfoliation in water of a nanosized graphite (HSAG) was obtained thanks to the synergy between a graphene layer edge functionalized with hydroxy groups and a polymer such as chitosan (CS). The edge functionalization of graphene layers was performed with a serinol derivative containing a pyrrole ring, serinol pyrrole (SP). The adduct between CS and HSAG functionalized with SP was formed simply with a mortar and pestle, then preparing water dispersions stable for months in the presence of acetic acid. Simple casting of such dispersions on a glass support led to carbon papers. Aerogels were prepared through the freeze-dry procedure. Exfoliation was observed in both these families of composites and ultra-high exfoliation was documented in aerogels swollen in water. Carbon papers and aerogels were stable for months in solvents in a wide range of solubility parameter and in a pretty wide range of pH. By considering that a moderately functionalized nanographite was straightforwardly exfoliated in water in the presence of one of the most abundant biobased polymers, the obtained results pave the way for the simple and sustainable preparation of graphene-based nanocomposites. HSAG-SP/CS adducts were characterized by wide angle X-ray diffraction (WAXD), scanning and transmission electron microscopy (SEM, TEM and HRTEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Thermal stability of the composites was studied by thermogravimetric analysis (TGA) and their direct electrical conductivity with the four-point probe method.

Hard carbon is regarded as a promising anode material for sodium-ion batteries (SIBs). However, it usually suffers from the issues of low initial Coulombic efficiency (ICE) and poor rate performance, severely hindering its practical application. Herein, a flexible, self-supporting, and scalable hard carbon paper (HCP) derived from scalable and renewable tissue is rationally designed and prepared as practical additive-free anode for room/low-temperature SIBs with high ICE. In ether electrolyte, such HCP achieves an ICE of up to 91.2% with superior high-rate capability, ultralong cycle life (e.g., 93% capacity retention over 1000 cycles at 200 mA g -1 ) and outstanding low-temperature performance. Working mechanism analyses reveal that the plateau region is the rate-determining step for HCP with a lower electrochemical reaction kinetics, which can be significantly improved in ether electrolyte., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Graphene/carbon paper is prepared by pyrolyzing graphene modified cellulose filter paper and directly used as a binder-free electrode to assemble a supercapacitor (SC) with a redox active electrolyte, containing a Fe 3+ /Fe 2+ additive. By the graphene incorporation and the carbonization of the cellulose fibers, both the microstructure and the electrical conductivity of the carbon paper are promoted greatly. The filter paper derived carbon (FPC) electrode exhibits a specific capacitance ( C s ) of 2832 F·g -1 in a 1 M H 2 SO 4 + 0.5 M Fe 3+ /Fe 2+ electrolyte at 1 A·g -1 , which is about 81 times that in a normal H 2 SO 4 electrolyte. With the modification of graphene, the capacitive performance of the SC is enhanced further and a remarkable C s of 3396 F·g -1 at 1 A·g -1 is achieved for a graphene modified filter paper carbon (GFPC) electrode, which remains at ~632 F·g -1 at 10 A·g -1 . The free standing GFPC electrode also exhibits good cycling stability (93.8% of capacitance retention after 2000 cycles) and an energy density of 118 Wh·kg -1 at a power density of 500.35 W·kg -1 , all of which are much higher than those of FPC. These encouraging results suggest that the graphene modification of electrode materials combined with a Fe 3+ /Fe 2+ redox active electrolyte is a prospective measure to fabricate SC with an ultrahigh performance.

Freestanding electrodes composed of 2D materials are highly attractive for many applications such as batteries, membranes, actuators, optical devices, and other energy-related devices owing to their low price, unique structure, high specific surface area, and excellent mechanical and electrical properties. Here, we report the facile large-scale fabrication of freestanding hierarchical carbon nitride/carbon electrodes (CN/C) by the in situ crystallization of CN precursors on conductive carbon paper, followed by thermal annealing. The resulting CN exhibits a vertically aligned morphology with a homogeneous layer distribution, improved crystallinity, and excellent contact with the carbon paper. The freestanding electrodes exhibit high electrical conductivity and good photoelectrochemical activity as anodes in water splitting photoelectrochemical cells. Furthermore, we show here as a proof-of-concept that the freestanding CN/C electrodes can be used as photoelectrocatalysts for the oxidative degradation of organic compounds in water, with enhanced activity compared to photocatalytic and electrocatalytic degradation, while the extracted electrons can be used for the simultaneous production of hydrogen at the cathode.

Sluggish vanadium reaction rates on the porous carbon electrodes typically used in redox flow batteries have prompted research into pretreatment strategies, most notably thermal oxidation, to improve performance. While effective, these approaches have nuanced and complex effects on electrode characteristics hampering the development of explicit structure-function relations that enable quantitative correlation between specific properties and overall electrochemical performance. Here, we seek to resolve these relationships through rigorous analysis of thermally pretreated SGL 29AA carbon paper electrodes using a suite of electrochemical, microscopic, and spectroscopic techniques and culminating in full cell testing. We systematically vary pretreatment temperature, from 400 to 500 °C, while holding pretreatment time constant at 30 h, and evaluate changes in the physical, chemical, and electrochemical properties of the electrodes. We find that several different parameters contribute to observed performance, including hydrophilicity, microstructure, electrochemical surface area, and surface chemistry, and it is important to note that not all of these properties improve with increasing pretreatment temperature. Consequently, while the best overall performance is achieved with a 475 °C pretreatment, this enhancement is achieved from a balance, rather than a maximization, of critical properties. A deeper understanding of the role each property plays in battery performance is the first step toward developing targeted pretreatment strategies that may enable transformative performance improvements.

The conventional gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells incorporates a carbon-based substrate, which suffers from electrochemical oxidation as well as mechanical degradation, resulting in reduced durability and performance. In addition, it involves a complex manufacturing process to produce it. The proposed technique aims to resolve both these issues by an advanced 3D printing technique, namely selective laser sintering (SLS). In the proposed work, polyamide (PA) is used as the base powder and titanium metal powder is added at an optimised level to enhance the electrical conductivity, thermal, and mechanical properties. The application of selective laser sintering to fabricate a robust gas diffusion substrate for PEM fuel cell applications is quite novel and is attempted here for the first time., Competing Interests: The authors declare no conflict of interest.

Ideally, if the corrosion resistance coating on carbon paper (CP) can be endowed with the self-healing property, the service life and the reliability of the carbon paper will be greatly increased as the gas diffusion layer. In this paper, different cycles of s branched poly (ethyleneimine) (bPEI) and poly (acrylic acid) (PAA) were modified on the surface of the carbon paper via layer-by-layer (LbL) self-assembly technology. The prepared polyelectrolyte multilayered coatings can not only protect the carbon fiber from corrosion, but also take advantages of the surrounding water to quickly repair themselves after damaged. The effects of the assembly cycles on morphology, resistance, air permeability and the contact angle of carbon papers were investigated, then the differences of the carbon papers in electrolysis process were explored. The results reveal that all the prepared coatings can protect carbon papers from corrosion, while when the assembly cycles was 10, the coatings are most efficient., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Vanadium flow batteries (VFBs) have received high attention for large-scale energy storage due to their advantages of flexibility design, long cycle life, high efficiency, and high safety. However, commercial progress of VFBs has so far been limited by its high cost induced by its low power density. Ultrathin carbon paper is believed to be a very promising electrode for VFB because it illustrates super-low ohmic polarization, however, is limited by its low electrocatalytic activity. In this paper, a kind of carbon paper (CP) with super-high electrocatalytic activity was fabricated via a universal and simple CO 2 activation method. The porosity and oxygen functional groups can be easily tuned via this method. The charge transfer resistance (denoting the electrochemical polarization) of a VFB with CP electrode after CO 2 activation decreased dramatically from 970 to 120 mΩcm 2 . Accordingly, the energy efficiency of a VFB with activated carbon paper as the electrode increased by 13% as compared to one without activation and reaches nearly 80% when the current density is 140 mAcm -2 . This paper provides an effective way to prepare high-performance porous carbon electrodes for VFBs and even for other battery systems.

The influence of electrode surface chemistry over biofilm growth was evaluated for photo-bioelectrocatalytic fuel cell. A consortium of photosynthetic bacteria was grown onto different electrodes designed with polyethylenimine (PEI) and multiwall carbon nanotubes as hydrophilic and hydrophobic modifier, respectively. The designed electrodes were loaded with 0.08, 0.17, and 0.33 μg/cm 2 of PEI to change the hydrophilicity. However, 0.56, 0.72, and 0.83 mg/cm 2 of multiwall carbon nanotubes were used to alter the hydrophobicity of the electrodes. The surface chemistry of electrode and bio-interaction was evaluated as a function of contact angle and biofilm formation. The results were compared with those obtained with a carbon paper electrode. The contact angle on the untreated electrode (carbon paper) was 118°, whereas for hydrophobic and hydrophilic electrodes, the maximum and minimum contact angles were 170° and 0°, respectively. Interestingly, the maximum biofilm growth (0.2275 g, wet basis) was observed on highly hydrophobic surface; however, the maximum electrochemical performance (246 mV) was shown by the most hydrophilic electrode surface. PEI-based electrode with good biofilm formation showed comparatively higher electrogenic activity., (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lithium sulfide (Li2S) with a high theoretical capacity of 1166 mAh g(-1) is a promising cathode material for Li-S batteries as it allows for the use of lithium-free anodes. However, a large overpotential (~1 V) is usually needed to activate microsized Li2S particles due to their low electronic and ionic conductivities. Here, nano-Li2S/carbon paper electrodes are developed via a simple Li2S solution filtration method. Li2S nanocrystals with a size less than 10 nm are formed uniformly in the pores of carbon paper network. These electrodes show an unprecedented low potential difference (0.1 V) in the first and following charges, also show high discharge capacities, good rate capability, and excellent cycling performance. More specifically, the nano-Li2S/carbon nanotube paper electrodes show a reversible capacity of 634 mAh g(-1) with a capacity retention of 92.4% at 1C rate from the 4th to 100th cycle, corresponding to a low capacity fading rate of 0.078% per cycle. These results demonstrate a facile and scalable electrode fabrication process for making high performance nano-Li2S/carbon paper electrodes, and the superior performance makes them promising for use with lithium metal-free anodes in rechargeable Li-S batteries for practical applications.

Lithium-sulfur (Li-S) batteries are considered to be the next-generation rechargeable systems due to their high energy densities and low cost. However, significant capacity decay over cycling is a major impediment for their practical applications. Polysulfides Li2Sx (390% over 50 cycles at C/10 rate. With LiNO3 additive in the electrolyte, the cell shows a reversible capacity of >1000 mAh g(-1) and a capacity retention of >80% over 100 cycles at C/5 rate.

Although much progress has been made to develop high-performance lithium-sulfur batteries (LSBs), the reported physical or chemical routes to sulfur cathode materials are often multistep/complex and even involve environmentally hazardous reagents, and hence are infeasible for mass production. Here, we report a simple ball-milling technique to combine both the physical and chemical routes into a one-step process for low-cost, scalable, and eco-friendly production of graphene nanoplatelets (GnPs) edge-functionalized with sulfur (S-GnPs) as highly efficient LSB cathode materials of practical significance. LSBs based on the S-GnP cathode materials, produced by ball-milling 70 wt % sulfur and 30 wt % graphite, delivered a high initial reversible capacity of 1265.3 mAh g(-1) at 0.1 C in the voltage range of 1.5-3.0 V with an excellent rate capability, followed by a high reversible capacity of 966.1 mAh g(-1) at 2 C with a low capacity decay rate of 0.099% per cycle over 500 cycles, outperformed the current state-of-the-art cathode materials for LSBs. The observed excellent electrochemical performance can be attributed to a 3D "sandwich-like" structure of S-GnPs with an enhanced ionic conductivity and lithium insertion/extraction capacity during the discharge-charge process. Furthermore, a low-cost porous carbon paper pyrolyzed from common filter paper was inserted between the 0.7S-0.3GnP electrode and porous polypropylene film separator to reduce/eliminate the dissolution of physically adsorbed polysulfide into the electrolyte and subsequent cross-deposition on the anode, leading to further improved capacity and cycling stability.