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Improving the reaction interface is imperative for increasing catalyst utilization and enhancing overall cell performance in proton exchange membrane electrolyzer cells (PEMECs). Herein, a thin Nafion-carbon-mixed microporous layer coated carbon paper (Nafion-C MPL/CP) is first developed as an efficient cathode liquid/gas diffusion layer for PEMECs. With the Nafion-C MPL/CP, low cell voltages of 1.64, 1.74 and 1.84 V are delivered, which are 50, 80 and 140 mV lower than those of the conventional bare carbon paper at 2, 4 and 6 A/cm2, respectively, achieving about 3-fold higher catalyst utilization. Meanwhile, superior performance is also demonstrated compared to the commercial PTFE-C MPL/CP. The remarkable performance of the Nafion-C MPL/CP should be attributed to the enhanced reaction interface, which not only provides rich active sites with abundant electron and proton transport pathways for the electrochemical reaction but also reduces the interfacial contact resistance and mass transport losses. Moreover, excellent stability of the Nafion-C MPL/CP is demonstrated at a current density of 1.8 A/cm2 with no performance degradation during over 100-h operation. Due to the enhanced reaction interface with significantly improved catalyst utilization, the developed Nafion-C MPL/CP shows great potential to reduce the hydrogen production cost and accelerate PEMEC commercialization. [ABSTRACT FROM AUTHOR]

In the quest for more sustainable chemical processes, we devised a technique using electro-organocatalysis to synthesize bis- β -diketone compounds via Knoevenagel condensation of benzaldehyde and dimedone. Our approach involves a modified electrode fabricated via anchoring L-proline onto a carbon fiber paper electrode supported by poly-3,4-diaminobenzoic acid (PDABA), which enhances efficiency in addition to the simple catalyst separation from the reaction mixture in heterogeneous catalysis. The electrochemical and surface topographical studies for the fabricated electrode were carried out, revealing high efficiency in comparison to the bare carbon fiber paper electrode. This electrochemical reaction operates under mild conditions utilizing lithium perchlorate and acetonitrile, yielding high amounts of the desired product. This study showcases a promising pathway for producing valuable organic compounds in an environmentally friendly manner, marking a significant stride forward in sustainable synthesis practices. [Display omitted] [ABSTRACT FROM AUTHOR]

• A bifunctional catalyst is synthesized by one-step thermal exfoliation. • The best catalyst shows overpotential of 254 mV at 10 mA/cm2 in alkaline seawater. • It exhibits excellent selectivity towards OER over hypochlorite formation. • The seawater electrolyzer shows a stability of 210 h at 20 mA/cm2. • A zero-gap electrolyzer is fabricated and performance is demonstrated. Developing bifunctional, non-precious catalysts for seawater electrolysis is pivotal yet remains challenging due to sluggish oxygen and hydrogen evolution reactions (OER and HER) and chlorine corrosion. Herein, Ni-NiFe 2 O 4 /rGO (NFO1/erGO) obtained by a one-step exfoliation is reported as a bifunctional catalyst for seawater electrolysis. The NFO1/erGO (85.3 % NiFe 2 O 4 , 14.7 % Ni) exhibits outstanding OER and HER activities in seawater. The NFO1/erGO/Carbon paper(CP)||NFO1/erGO/CP electrolyzer demonstrates low overall seawater splitting voltages of 1.74 V and 1.98 V to achieve 10 mA/cm2 and 100 mA/cm2, respectively. Electronic charge modulation across the metal centres, enhanced conductivity, optimum binding strength of reaction intermediates, and corrosion resistance ensure excellent stability and electrocatalytic activity. Interestingly, NFO1/erGO maintains its original phase even after seawater electrolysis, suggesting its exceptional structural durability. Finally, a membrane-less zero-gap seawater electrolyzer is fabricated, demonstrating an H 2 production rate of 0.36 L/h. These observations boost the practical realization of seawater electrolyzers based on non-precious catalysts. [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]

To further enhance the long-term durability of the cost-effective Ir-based catalysts, some acid-stable oxides are used as supports for acidic OER catalysts. Herein, taking carbon paper (CP) as the substrate, we prepared a self-standing IrW/WO 3-x @NC/CP electrode via a layer-by-layer modified method. Among it, N-doped porous C framework not only provides a large specific surface for the attachment of WO 3-x , but also makes up for the lack of conductivity of WO 3-x and accelerates the electron transport process. The interaction between Ir and W sites in the form of IrW alloy which has generated during the high-temperature calcination and the dispersed Ir in WO 3-x matrix improve the intrinsic catalytic activity. And due to the Pt-like effect of W and the tuning role of the electronic structure by the IrW alloy, IrW/WO 3-x @NC/CP with an Ir content of only 19.1 µg cm−2 exhibits excellent bifunctional activity in acidic media. To obtain 10 mA cm−2, IrW/WO 3-x @NC/CP just needs overpotential of 22 mV (for HER) and 206 mV (for OER) respectively with a mass specific activity of 4.008 A mg Ir −1 at 1.55 V. For the whole water splitting, it only requires 1.52 V and 1.70 V to reach 10 mA cm−2 and 100 mA cm−2 respectively, and can operate continuously for over 40 h. [ABSTRACT FROM AUTHOR]

• Development of a dual-templated molecularly imprinted electrochemical sensor for the simultaneous analysis of brilliant blue FCF and tartrazine. • MIP film was generated by electro-polymerization of 3-aminophenyl boronic acid with brilliant blue and tartrazine as templates. • High surface area modification enables the formation of complementary binding sites for both analytes on the MIP sensor surface during fabrication. • Successful application of the developed sensor in real food samples. In this study, a dual-templated molecularly imprinted polymer-based electrochemical sensor was developed for the simultaneous analysis of two food additive dyes, brilliant blue FCF and tartrazine. Using a 3-aminophenyl boronic acid (3-APBA) monomer and the dual templates of brilliant blue FCF (BB) and tartrazine (TZ), the molecularly imprinted polymer (MIP) layer was electropolymerized on the carbon fibre paper (CFP) electrode. By using BB and TZ as template molecules along the electro-polymerization of 3-APBA, then removing both template molecules, the MIP film was generated on the surface of the CFP electrode. Due to the high surface area provided by modification, several complementary binding sites for template molecules are formed on the surface of the MIP sensor during this process of sensor fabrication. On the MIP/CFP electrode, the electrochemical behavior of BB and TZ was assessed. The monomer/template ratio, pH values, and influencing parameters like the electro-polymerization scanning cycles were all optimized. This sensor was applied to detect brilliant blue FCF and tartrazine in beverage and food samples using MIPAPBA/CFP electrode. [Display omitted] Graphical representation of the sensor fabrication process [ABSTRACT FROM AUTHOR]

Due to the shuttle effect brought by polysulfides, the commercialization of lithium-sulfur batteries still faces significant difficulties. Carbon interlayer is introduced to enhance the electrochemical performance of lithium-sulfur batteries, while the drawback that the interlayer will reversely affect the performance of the current collector was ignored. The current collector has a significant influence and contribution to the cycle stability of lithium-sulfur batteries. In this study, we looked into the electrochemical stability and corrosion situation of standard aluminum foil collectors in lithium-sulfur batteries with carbon interlayer. The results show that the introduction of carbon interlayer into the lithium-sulfur batteries will make aluminum foil and carbon paper form an electronic conduction path and galvanic corrosion occurs, accelerating the corrosion of aluminum foil. Therefore, we propose a new corrosion model. During the cycle, the surface of the aluminum collector becomes a non-dense passivation film and lithium polysulfide terminal (S T −1). Then, under the action of the carbon interlayer, the passivation film peels off and the oxide film is attacked by the electrolyte, thiosulfate and polythionate, resulting in pitting holes and ultimately accelerating the corrosion of the aluminum foil collector. This research has some guiding significance for the commercial application of lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS 2) can effectively improve the efficiency of hydrogen evolution reaction (HER) and reduce the cost of hydrogen production. However, MoS 2 is kinetically sluggish in alkaline media, which makes it difficult to apply directly to HER. In order to improve the applicability of MoS 2 in HER, this paper designs a hierarchical NiFe-LDH/MoS 2 nanosheet with a heterogeneous interface anchored on carbon fiber paper (CFP) to optimize the performance of MoS 2. The experimental results show that the NiFe-LDH/MoS 2 /CFP electrode in 1.0 M KOH exhibits excellent HER activity with only 88.5 mV overpotential at 10 mA cm−2. The good performance is attributed to numerous active sites on the NiFe-LDH/MoS 2 heterogeneous surface, the good electrical conductivity of MoS 2 and CFP, as well as the pores distributed on NiFe-LDH/MoS 2 that facilitate mass transfer. It is also found that the catalyst exhibits outstanding stability (24 h) in alkaline media. This work opens up new prospects for the development of high-performance electrocatalysts in alkaline media. [ABSTRACT FROM AUTHOR]

Synthesis of affordable electrocatalysts with high efficiency at low cost is crucial for large-scale water splitting. Molybdenum carbide (Mo 2 C) has been suggested to be a promising alternative to noble metal based electrocatalysts for water splitting. In this paper, we fabricated a nanotextured coating of wrinkled Ni-doped Mo 2 C on carbon fiber paper (CFP) from Ni, Mo and carbon black (CB) via a molten salt method. Such a novel electrocatalyst, denoted as Ni-Mo 2 C CB /CFP, shows an overpotential of 121.4, 209.3 and 426.4 mV to achieve a current density of 10, 20 and 50 mA cm−2 respectively in acidic medium. The hydrogen evolution reaction (HER) performance of other as-prepared CFP based electrodes (bare CFP, Mo 2 C/CFP, Mo 2 C CB /CFP, Ni-Mo 2 C/CFP and NiC x /CFP) also tested. We found that the addition of carbon black and the doping of Ni could significantly improve the electrocatalytic performance of Mo 2 C/CFP in terms of overpotential, Tafel slope and exchange current density. This work demonstrates a facile and scalable route using molten salt method for the synthesis of high-performance electrocatalysts from non-precious compounds on carbon materials. Image 1 • Carbon fiber paper (CFP) was employed as a carbon source and substrate of Mo 2 C. • The addition of carbon black (CB) contributes to the refinement of Mo 2 C particles. • Ni-Mo 2 C/CFP composite was prepared from Ni, Mo, CFP and CB by a molten salt method. • The Ni-Mo 2 C/CFP electrocatalyst exhibits excellent catalytic performance for HER. [ABSTRACT FROM AUTHOR]

Development of high energy density supercapacitor has stimulated a great deal of research over the past decade. The electrochemical performance of a hybrid supercapacitor is strongly affected by the structural morphology and the surface area of its electrode material. Herein, we report mesoporous nanosheet structures composed of copper sulfide which are synthesized by an instant and simple microwave-assisted method. The electrode material based on CuS nanosheets consist of mesoporous structures (pore diameter < 25 nm) and a large surface area (∼169 m 2 g−1). This high surface area nanosheets structure provides more active sites for electrochemical reactions and short ion/electron diffusion path for excellent super-capacitive performance. The mesoporous CuS nanosheets electrode exhibits a high specific capacitance of 2535 Fg−1 at a current density of 1 Ag−1 in an aqueous electrolyte (2MKOH) with excellent rate capability. The fabricated device for practical application possesses an excellent energy density of 63.2 Whkg−1 at a high power density of 400W kg−1, the good specific capacitance of 177 Fg−1 at 0.5A g−1 and high cycling stability at 10 Ag−1 (88% retention after 10000 cycles). This work not only demonstrates the promising potential of the mesoporous CuS electrodes for application in the high-performance hybrid asymmetric capacitor but also shows a path to synthesize different transition metal sulfide architecture by using microwave radiation method. Image 1 • Fast and easy, microwave assisted one step method to prepare CuS nanosheets. • A very high surface area of ∼169 m 2 g−1 and mesoporous nanostructure (pore diameter < 25 nm). • Excellent specific capacitance of 2535 Fg−1 at 1Ag−1 inert carbon fibre paper current collector. • Assembled hybrid asymmetric capacitor delivers a high energy density of 63.2 Whkg−1. • Excellent cyclic performance (88% retention after 10000 cycles). [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 Two-dimensional graphene-based materials are of great interest in electrochemical energy storage devices owing to their high theoretical specific capacitance; however, it is a big challenge to approach the theoretical limit. Here, we report a facile strategy for the selective production of N -doped graphene nanosheets (NGNS) in quasi-closed montmorillonite (MMT), which act as a nanoreactor and open only along the perimeter to enable the entrance of aniline (AN) monomer. As a proof of concept applications, as-synthesized NGNS are used as the electrode material for a symmetric supercapacitor (SSC). The NGNS supported on carbon paper (NGNS@CP) exhibits excellent capacitive performance in an aqueous neutral electrolyte (LiCl) by achieving a high capacitance of 480 and 472 F g−1 at 1 A g−1 for negative and positive electrodes, respectively. The NGNS@CP electrode also shown outstanding rate capabilities and cycling stabilities in positive and negative voltage windows by retaining the 98.07, and 99.44 % of the original value, respectively. Moreover, the assembled flexible symmetric supercapacitor (NGNS@CP//NGNS@CP) using LiCl/PVA hydro-gel electrolyte can operate at high voltage window of 0.0–2.0 V and achieved an ultra-high energy density of 82.72 Wh kg−1 at a moderate power density of 425.68 W kg−1 with remarkable cycling stability of 96.91 % over 10000 charge/discharge cycles. Furthermore, the NGNS@CP//NGNS@CP demonstrates excellent flexibility and one device can power the two light-emitting diodes brightly. The achieved energy density of the NGNS@CP//NGNS@CP is much superior to the previous graphene-based SSCs and suggests a new generation of ultra-fast symmetric supercapacitor as novel high-performance energy storage devices. Graphical abstract The defective N -doped graphene nanosheets supported on carbon paper exhibit superior electrochemical performance as positive and negative electrodes for SC. The as-fabricated NGNS@CP//NGNS@CP SC demonstrates excellent flexible performance as well as outstanding energy density. Image 1 Highlights • The highly defective N -doped graphene nanosheets (NGNS) are synthesized in a quasi-closed MMT nanoreactor. • NGNS supported on carbon paper exhibit superior electrochemical performance as positive and negative electrodes. • NGNS@CP//NGNS@CP symmetric SC demonstrates excellent flexible performance. • NGNS@CP//NGNS@CP symmetric SC displays outstanding energy storage capability. [ABSTRACT FROM AUTHOR]

Abstract New multi-metallic materials have been synthesized to be used as active anodes in direct alcohol fuel cells. However, the separate steps of synthesis, characterization and preparation of the catalyst layer prior to their use are costly and time-consuming. Here, we propose a sustainable new method to in situ decorate catalysts with ad-atoms in flow-through porous electrode configuration. The ad-atoms are electrodeposited in a microfluidic fuel cell by driving the metallic precursor through the electrode under applied potential while blank electrolyte feeds the other half-cell porous electrode. Pt/C-modified carbon paper is decorated with Fe, which is subsequently used as an anode during operating the cell as a microfluidic direct glycerol fuel cell. The ultralow mass of Fe is calculated by integrating the reduction charge, in which the high residence time under controlled flow conditions increases the amount of Fe on Pt/C. The decoration can also be controlled by changing the concentration of the precursor, which is limited by the availability of Pt active sites. The power density of the obtained cell in flow-through porous electrode configuration is enhanced by 36% using the Fe-decorated anode, reaching ∼54 mW cm−2 at ∼0.7 V under mixed media conditions. Hence, the proposed method provides an effective means to modify, analyze and use bimetallic anodes at the same instrument and can be applied post-fabrication in any fuel cell or other flow cells with porous electrodes. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract Developing efficient bifunctional electrocatalysts and gaining fundamental understanding of reaction mechanisms are crucial for practical water splitting. Herein, a bifunctional NiSe 2 nanoparticles/carbon fiber paper (NSN/CFP) electrode is fabricated by the pyrolysis of Ni(NO 3) 2 on CFP, followed by a selenization step. The as-prepared electrocatalysts exhibit superior overall water splitting behavior in 1 M KOH with low overpotentials of 145 mV and 280 mV at current densities of 10 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) respectively, comparable to the performance of 20% Pt/C and RuO 2. Detailed compositional and morphological studies reveal that the NiSe 2 gradually transforms into an amorphous Ni(OH) 2 /NiOOH heterojunction during both HER and OER in alkaline medium. Based on these experimental results, an oxidation-induced self-reconstruction mechanism is proposed. Owing to the highly-oxidized Ni(OH) 2 /NiOOH active species, the self-reconstructed structure enhances the water splitting under fixed potentials for a prolonged time of 96 h with negligible current degradation. This work not only provides a facile route to fabricate efficient and stable electrocatalysts for large-scale water splitting but also reveals an underlying structural evolution mechanism, which guides the rational design of heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Abstract In this paper, carbon paper (CP) was modified by three-dimensional reduced graphene oxide (3DrGO/CP) and binders. Based on physical (field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Raman spectroscopy) and electrochemical tests (cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charging/discharging curves), the physical and chemical properties of 3GrGO/CP electrode were investigated. The physical characterization and electrochemical performance analysis indicated that the different binders significantly influenced the hydrophilicity and the wet surface area of electrode. Nitrogen doping three-dimensional reduced graphene oxide facilitates the electron transfer on electrode/electrolyte interface for both oxidation and reduction processes of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (4-HO-TEMPO), provides more reaction area and reduces concentration polarization. Therefore, the modified carbon paper electrode exhibits better electrochemical activity and reversibility compared with the pristine carbon paper electrode in a methyl viologen (MV)/4-HO-TEMPO redox flow battery (RFB). Graphical abstract Image 1 Highlights • N doping 3DrGO facilitates the electron transfer on electrode/electrolyte interface for 4-HO-TEMPO redox reactions. • The different binders significantly influenced the hydrophilicity and the wet surface area of electrode. • This simple modification method can effectively improve the performance of the RFB. [ABSTRACT FROM AUTHOR]

Abstract The structural design and synthesis of sulfur-carbon composite materials with high performance is still a major challenge for rechargeable lithium-sulfur batteries. Interconnected three-dimensional frameworks comprising multi-walled carbon nanotubes, graphene, or carbon particles offer a combination of constituent advantages and can thus be used to achieve superior energy conversion and storage properties. Herein, we designed and prepared free-standing three-dimensional sulfur papers containing interconnected highly conductive carbon materials, which enable to be flexible binder-free cathodes for Li-S batteries. The resultant sulfur-carbon composite paper cathode exhibited high reversible specific capacity of 1386 mAhg−1, good rate capability up to 5C, and excellent cycling performance (a capacity retention 68% after 400 cycles), all of which are significantly improved from those of bare sulfur cathode or sulfur-GO composite only. Rational design of cathode composition, structure, and a simple fabrication process can give insight into the development of various advanced cathode materials for high-performance Li-S batteries. Graphical abstract Image 1 Highlights • The composition of in-situ formed sulfur particles on the surface of GO with conductive carbons was designed and prepared. • Highly flexible and conductive S-GO/SP and S-GO/MWCNT papers were used the cathode for Li-S battery. • The use of composite papers allowed high reversible capacity and stable cycling performance. • The use of S-GO/MWCNT composite papers improved the rate capability. • The interconnected 3D framework was able to suppress the migration of polysulfides and irreversible agglomeration/deposition. [ABSTRACT FROM AUTHOR]

One of the major challenges towards the development of the conventional alkaline Zn-air battery is its spontaneous discharge caused by the unstability of the anode Zn in concentrated alkaline electrolyte. Utilization of a neutral electrolyte as the alternative to alkaline electrolyte is likely to be a promising strategy to overcome this issue because of much high stability of anode Zn in neutral solution. To realize the normal operation of the neutral Zn-air battery however, a crucial issue is how to ensure that the cathodic catalyst can efficiently electro-catalyze oxygen reduction reaction (ORR) in neutral solution. Herein, we report a facile preparation of Ni/Co-doped C-N nano-composite catalysts (NiCo/C-N) from direct pyrolysis of Ni/Co salt, polyaniline (PANI), carbon nanotube (CNT) and dicyandiamide. Among the as-synthesized catalysts, Ni 1 Co 3 /CN-3 presents high and stable ORR current density of 5.27 mA cm −2 in 0.5 mol L −1 KNO 3 solution at 2000 rpm. Electron transfer number of ORR on Ni 1 Co 3 /CN-3 catalyst is 3.78, showing a nearly completed reduction of O 2 to H 2 O. A neutral Zn-air battery with the prepared NiCo/C-N composite coated on carbon paper as the air electrode catalyst and metal Zn as the anode was constructed in 0.5 mol L −1 KNO 3 solution. For the catalyst Ni 1 Co 3 /CN-3, the open circuit voltage of the neutral Zn-air battery is 1.16 V, and the maximum power density is 38.5 mW cm −2 . The galvanostatic discharge time is 345.7, 160.6, 18.1 and 1.3 h as the discharge current density keeps 10, 50, 100 and 150 mA cm −2 respectively. A stable voltage plateau arises at various discharge current densities. The neutral Zn-air battery can repeatedly discharge after the zinc anode has been replaced, indicating that the synthesized ORR catalyst is an excellent cathode material for the neutral Zn-air battery. This kind of neutral Zn-air battery has a wide application prospect as mobile power supply. [ABSTRACT FROM AUTHOR]

In this work, we report an environmentally friendly and low-cost approach to synthesize an all biomass-derived electrode from cotton through a pyrolysis process and apply this novel electrode to a VRFB for the first time. It is demonstrated that this carbonized cotton (CC) electrode presents a higher BET surface area, a larger number of oxygen-containing functional groups, a better wettability and higher catalytic activity for vanadium reactions than commercial carbon papers (CPs) do. As a result, the CC electrode improves the reversibility toward VO 2+ /VO 2 + by 100 mV lower peak separation as compared with commercial CPs. Moreover, the VRFB assembled with the prepared electrodes delivers a high voltage efficiency of 75.4% at a current density of 100 mA cm −2 , outperforming the oxidized CPs (68.3%), and a better rate performance during the charge-discharge test at various current densities. These results suggest that the carbonized cotton electrode offers a great promise for the large-scale application in VRFBs. [ABSTRACT FROM AUTHOR]

In this paper, we synthesize a new type of Ni-Co selenides (Ni 0.34 Co 0.66 Se 2 nanorod) on carbon fiber paper (CFP) as flexible electrode for supercapacitor. Comparing with NiCo 2 O 4 and NiCo 2 S 4 , the Ni 0.34 Co 0.66 Se 2 exhibits superior capacitive performance including high areal capacitance (2.61 F cm −2 at 4 mA cm −2 ), good rate capability (75% of retention from 4 to 20 mA cm −2 ) and excellent long-term cycling stability (only 7.4% of loss after 6000 cycles). When assembled into a symmetric supercapacitor, the as-obtained, Ni 0.34 Co 0.66 Se 2 based device possesses a volumetric capacitance of 14.55 F cm −3 at 1 mA cm −2 , and a volumetric energy density of 0.47 mWh cm −3 at 10 mA cm −2 , which are superior to most of the symmetric supercapacitors reported previously. Then we explore the energy storage mechanism of Ni 0.34 Co 0.66 Se 2 by monitoring the changes in component, morphology, electroactive surface area (ESA) and electron transport characteristics. It is found that the Ni 0.34 Co 0.66 Se 2 species suffer from serious Se loss and transform into Ni x Co 1-x O gradully during charge/discharge cycles, but the ESA increases significantly in this process. In addition, the Ni 0.34 Co 0.66 Se 2 electrode possesses lower internal resistance, indicating its good electron transfer properties. Both these factors will compensate the performance degradation from Se loss, resulted in better rate capability and cycling stability for Ni 0.34 Co 0.66 Se 2 electrode. Therefore, it is believed that the proposed 3D Ni 0.34 Co 0.66 Se 2 nanorod array modified CFP with optimizational component and structual design opens a new horizen in the development of high-performance flexible supercapacitor electrode with new charge storage mechanism. [ABSTRACT FROM AUTHOR]

Water splitting associated with the conversion and storage of renewable energy is considered to be the most significant strategy to create hydrogen. Herein, an efficient self-supported electrode was developed by in-situ growth of interlayer expanded lamellar cobalt diselenide (CoSe 2 ) nanosheets (NS) on carbon paper (CP) substrate (CoSe 2 NS@CP). The analyses of TEM, SEM and XRD confirmed that the CP is homogeneously coated by few stacking layers of interlayer expanded lamellar structured CoSe 2 . This rationally designed nanostructure can provide more active sites for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The bifunctional electrode exhibits high electrocatalytic performance with −128 mV vs. RHE onset potential for the HER in 0.5 mol dm −3 H 2 SO 4 and +1521 mV vs. RHE for the OER in 1.0 mol dm −3 KOH. Besides, small electrolysis potentials of −201.1 mV vs. RHE and +1636 mV vs. RHE are needed to drive the HER and OER at current density of 100 mA cm −2 . Finally, a small overall cell voltage ( ca. +1.75 V) was used to drive the water splitting reaction in 1.0 mol dm −3 KOH. The CoSe 2 NS@CP electrode showed both excellent catalytic activity with overall current density of 100 mA cm −2 at 2.13 V and tremendous durability with negligible decrease in potential at a constant current of 20 mA cm −2 for more than 30 hours. Thus this rationally designed electrode material can be readily applied for large-scale water splitting process. [ABSTRACT FROM AUTHOR]

• Enzymatic bioelectrode characterized for energy generation and biosensing purposes. • Bilirubin oxidase immobilized on carbon paper using PBSE as bifunctional crosslinker. • Biobattery successfully applied in powering a digital watch for over 2 h. • Biosensor revealed high sensitivity (606 μA mM−1 cm−2) and low LOD (1.3 μM) for O 2. • Response maintained (88%) for 34 days through constant bioelectrode reutilization. Biological systems can be envisaged as energy-sustainable solutions for both microenergy production to power small electronics and sensing purposes. In the present work, an enzymatic bioelectrode was characterized as biocathode in the fabrication of a biobattery and as biosensor for dioxygen detection. Carbon fibre paper was selected as transducer given its unique tailoring and electrocatalytic characteristics, being modified with carbon nanotubes for subsequent attachment of bilirubin oxidase enzyme. The immobilization process was based on a simple but effective method using the crosslinker 1-pyrenebutanoic acid N-hydroxysuccinimide ester, which creates stable bonds by maintaining a good response (88%) for over 34 days. The biobattery, that consisted of a zinc anode coupled with the developed biocathode, produced an open circuit potential of 1.69 V and maximum power of 40 μW, being capable of powering a digital watch for over 2 h. When applied as a dioxygen biosensor, the biocathode revealed high sensitivity of 606 ± 22 μA mM−1 cm−2 and low limit of detection of 1.3 ± 0.2 μM in chronoamperometric measurements at +0.4 V. The application of bilirubin oxidase in the fabrication of biobatteries is scarcely studied even given its advantages over other dioxygen reduction enzymes. Likewise, the use of the remarkable features of CP in dioxygen biosensing is yet to be explored. Therefore, this work stands as an interesting opportunity in the development of relatively simple and affordable bioelectrodes viably intended for energy and biosensing applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Cathodes consisting of carbon paper, electrode, and electrolyte are reconstructed. • An improved LBM model is developed for modeling the discharge process. • Time-dependent local porosity of cathode is considered by the proposed model. • The spatial distribution of electrode on O 2 diffusion and discharge are studied. The discharge process of lithium–oxygen battery (LOB) is a highly complicated multi-physics coupling phenomenon. Moreover, the cathode morphology presents a complex multi-scale structure with pore size ranging from nanometers to micronmeters, and plays a crucial role in determining the discharge performance. In this work, the cathodes consisting of carbon paper, electrode material, and electrolyte are first numerically reconstructed using a two-step reconstruction method considering the multi-scale morphology. A lattice Boltzmann model with an improved partial bounce-back scheme is proposed for modeling the discharge process given that the electrode porosity changes with the progress of discharge. The effects of micron-scale electrode spatial distribution on the O 2 diffusion and LOB discharge performance are investigated. Results show that the increment of the electrode dispersion degree increases the O 2 diffusion resistance due to the increase of electrolyte-electrode specific interface area. A large local electrode load near O 2 inlet leads to a high O 2 diffusion resistance and low O 2 concentration owing to the large specific interface area and electrode volume. Cathodes with the minimum electrode load and maximum electrode dispersion degree present the optimal specific capacity of LOB. However, the specific capacity first increases significantly and then slightly decreases with the increase of local electrode load. [ABSTRACT FROM AUTHOR]

Dealloyed ternary Cu@Pt-Ru core-shell electrocatalysts supported on carbon paper (CP) are fabricated by cyclic-co-electrodeposition and selective copper dealloying (CCED-SCuD). The physical properties of this catalyst such as surface and bulk compositions, electronic structure modification, phase structure, crystallite size, compressive lattice strain, and morphology were characterized by X-ray photoemission (XPS), inductive-coupling plasma atomic spectroscopy (ICP-AES), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscope, and transmission electron microscope (TEM). The best catalyst is Cu@Pt-Ru/CP, having core-shell structure with a Cu rich core and a Pt-Ru rich shell with grain size around 100 nm. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) reveal that ternary Cu@Pt-Ru/CP gives significantly low onset potential and high activity towards methanol electrooxidation reaction (MOR), achieving specific peak current at 265 mA.mg Pt −1 , which is significantly higher than that of dealloyed binary Cu@Pt/CP (211 mA.mg Pt −1 ) and pure Pt/CP (170 mA.mg Pt −1 ). The highest current stability is found for the ternary Cu@Pt-Ru/CP with decay rate at 2.3 × 10 −3 mA.mg Pt −1 .s −1 . The enhancements of both activity and stability of the Cu@Pt-Ru/CP from the higher electrochemical surface area (ECSA) are major reason, which originates from the higher exposed surface of Pt, while the higher compressive lattice strain, electronic structure modification, and bi-functional mechanism are minor reason. However, the lower current density (J P ) of the ternary Cu@Pt-Ru/CP suggests lower intrinsic reactivity. [ABSTRACT FROM AUTHOR]

A facile and sustainable electrochemical synthetic strategy for phenyl benzimidazoles has been developed using a ferrocene-based electrocatalyst anchored on Toray carbon paper (TCP) coated with conducting polymeric film. The developed electrode was used for the electrochemical dehydrogenative cyclization reaction of o -phenylene diamine and benzaldehyde using lithium perchlorate/acetonitrile as electrolyte. The surface characteristic properties of the developed electrode were characterized by FESEM, Optical profilometer and X-ray photoelectron spectroscopy. Electron transfer mechanism of the anchored ferrocene-based electrocatalyst was thoroughly studied. To determine the efficacy of the catalyst, the electron transfer coefficient (0.5) and apparent rate constant 41.4 s−1 were determined. The cyclic voltammetry studies reveal that the electrochemical oxidation peak for the synthesis of benzimidazole occurs at 0.48 V. The formation of the product was confirmed by Gas chromatography and Nuclear Magnetic Resonance spectroscopy. A comparison chart is presented for the green metrics and sustainability of the present strategy with other electrochemical approach. [Display omitted] [ABSTRACT FROM AUTHOR]

• A columnar liquid-crystalline triazine-based dendrimer has been incorporated as Li-ion battery anode. • The additional 1% carbon filler (CNT paper) in the triazine-based anode successfully boost the battery performance. • Systematical spectroscopic studies reveal that Li+ insertion in triazine and piperazine functional groups plays an important role in the Li+ storage mechanism. • The charge storage evaluation and kinetical studies unleashed the role of carbon filler on boosting capacitive contribution and accelerating Li+ transport. Owing to their highly tunable molecular structure and chemical stability, dendrimers consisting of triazine and piperazine moieties have been investigated. The present work describes the electrochemical performance of a columnar liquid-crystalline triazine-based dendrimer containing the linker with diaminopropane (DAP) as a lithium-ion battery anode. To elucidate the impact of conductive carbon filler in the electrode, a tiny amount of carbon nanotube (CNT) paper has been incorporated in the DAP anode. The battery performance revealed that the DAP anode has shown a high specific capacity of up to 444 mA h g−1 at 0.5 A g−1 after 200 cycles. Surprisingly, with an additional 1% CNT, the Li+ storage capacity of the dendrimer-based composite anode (DAP/CNT1%) significantly enhanced up to 656 mA h g−1. To the best of our knowledge, this is the first time that a triazine-based dendrimer has been utilized as an anode material in conjunction with a small amount of CNT to further boost its energy-storing capabilities through a synergy of capacitive storage mechanisms and improve Li+ transport. The efficient lithium storage of DAP/CNT composite further shows its amenability as organic electrode material for next-generation organic Li-ion batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

Porous 3-D current collectors have been shown to be the primary choice in replacing classical 2D aluminum foil in applicable developments, especially those using carbon-based current collectors. In this study, we investigated the impact of using a non-woven carbon (NWC) based current collector for sulfur electrodes, in terms of performance and practical use in a commercial battery, keeping in mind the simplicity of electrode preparation method. The benefits of using NWC as a 3D current collector include high sulfur utilization for even highly loaded electrodes, lower polarization, and the provision of an efficient electrolyte reservoir. High discharge capacities up to ∼1200 mAh g −1 can be obtained at moderate C-rates, with relatively good capacity retention (<1% loss per cycle) and practical loadings as high as 8 mAh cm −2 . [ABSTRACT FROM AUTHOR]

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

Highly uniform sputtered nanostructured silver (Nano-Ag) film on the conductive carbon paper (CP) substrate (Nano-Ag/CP) was applied as a novel approach for thiourea (TU) measurement in copper electrorefining bath. Nano-Ag film was achieved by direct current (DC) magnetron sputtering system at the optimized instrumental deposition conditions. Characterization of the surface structure of Nano-Ag film by field emission-scanning electron microscopy (FE-SEM), exhibits uniform Nano-Ag film as an effective transducer for TU sensing. Step by step monitoring of Nano-Ag/CP electrode fabrication were performed using electrochemical methods such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. Fabricated Nano-Ag/CP electrode was used for TU determination using EIS assessment. The impedimetric results show high sensitivity for TU sensing within 2.0–250 ppm. [ABSTRACT FROM AUTHOR]

• Variation of Young's modulus of Ga in the process of discharge (lithiation) was measured. • Self-healing ability of EGaIn to automatic repair the cracks resulted from charge/discharge. • The CNF/CNT@EGaIn NPs anode is free-standing, flexible and binder-free. Gallium-based liquid metals are considered as potential anode materials for lithium-ion batteries owing to their self-healing, non-poisonous advantages, as well as high theoretical capacity. However, due to the alloying/dealloying reaction mechanism to store lithium, Gallium-based alloys face huge volume change resulted in poor cycle life. Furthermore, the poor wettability of liquid metals on many kinds of substrates (carbon materials, stainless steel, etc.) and their strong ability to form alloys with many metallic current collectors (Cu, Al foil) make them hard to be designed into electrode with excellent electrochemical performance. One objective of this paper is to investigate Young's modulus of Ga discharged to different cut-off potentials, in order to gain a further understanding of mechanical property attenuation of Ga in the process of lithiation. Moreover, a three-dimensional (3D) free-standing electrode is fabricated by confining Ga-based liquid metal, EGaIn, in the matrix of carbon nanofibers/carbon nanotubes paper (CNF/CNT@EGaIn NPs). The network structure provides effective pathways for electrons and ions, as well as enough space to contain the volume expansion of EGaIn. The dense CNT layer plays a further role on preventing EGaIn from shedding of the conductive substrates. Obtained CNF/CNT@EGaIn NPs exhibits a good ionic/electronic conductivity and mechanical stability, delivers capacity of 351 mAh g−1 at 1.6 A g−1 and remains a reversible capacity of ∼420 mAh g−1 after 100 cycles at 800 mA g−1. This work could provide valuable insights into the development of Ga-based liquid metal anodes. [ABSTRACT FROM AUTHOR]

• Self-supporting x Ni-WC@CFP catalysts with fold-like structure were prepared through one-step molten salt method. • 4M Ni-WC@CFP showed excellent HER activity in 0.5 M H 2 SO 4 (overpotential of 73 mV at 10 mA cm−2 and Tafel slope of 66.4 mV dec−1). • The increasing concentration of Ni(NO 3) 2 promoted first and then inhibited the catalytic performance of x Ni-WC@CFP electrocatalysts, resulting from the synergistic effect of Ni and W on hydrogen adsorption energy. Exploring high-performance and inexpensive electrocatalysts for hydrogen evolution reaction to substitute Pt-based compounds is important to sustain hydrogen production. Herein, WC based self-supported catalysts doped with different concentration of nickel nitrate solution (Ni(NO 3) 2) were synthesized on carbon fiber paper (CFP) by one-step molten salt method (abbreviated as x Ni-WC@CFP). With the increasing of Ni(NO 3) 2 concentration, fold-like structures were formed on the catalysts, which was conducive to active sites exposure. As Ni(NO 3) 2 concentration increased from 1M to 5M, the catalytic performance of the electrocatalyst showed a trend of increasing first and then decreasing. The optimal 4M Ni-WC@CFP showed comparable catalytic ability in 0.5M H 2 SO 4 with a low overpotential of 73 mV at 10 mA cm−2 and Tafel slope of 66.4 mV dec−1. However, excessive nickel doping would inhibit HER performance. The density functional theory calculation further verified the experimental results. The adsorption energy of hydrogen showed a decreasing trend with the rising amount of Ni doped in, while the W-H binding energy would change in an opposite direction as over doped Ni. This work provided an insight for the preparation of high-efficiency self-supported W-based electrocatalysts and expounded the influence trend of Ni doping concentration on the performance of electrocatalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, Pt-Pd alloy catalyst was fabricated on carbon papers via electro-deposition as an alternative catalyst for oxygen reduction in air-cathode Microbial Fuel Cells (MFCs). Effects of electro-deposition cycles and supporting materials (graphene and carbon nanotubes (CNTs)) on oxygen reduction reaction (ORR) activity of the Pt-Pd electrode and power generation in MFCs were investigated. The structural and electrochemical properties of the Pt-Pd catalyst were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Results showed that the Pt-Pd electrode showed a good ORR activity. A MFC with a Pt-Pd cathode of 15 deposition cycles produced a maximum power density of 1274 mWm −2 , comparable to that with a conventional Pt/C cathode (0.5 mg Pt cm −2 ). CNT as the supporting material further increased ORR activity of the Pt-Pd electrode and power generation capacity in MFCs, while graphene as the supporting material did not produce positive effects. XRD results confirmed the presence of Pt/Pd elements on the electrode. SEM results showed that decoration using CNT reduced Pt-Pd particle size and promoted them even dispersion on the carbon paper. The Pt-Pd electrode attained a comparable performance to the Pt/C electrode when controlling an optimum deposition cycles and using CNT as the supporting materials, which demonstrates the potential of replacing Pt as an oxygen reduction catalyst in MFCs due to high oxygen reduction activity and relatively low cost. [ABSTRACT FROM AUTHOR]

The voltammetric behavior of the Ce(III)/(IV) half-cell reaction in various electrolytes containing 0.6 M Ce was investigated on both pristine and metal-modified carbon paper (CP) electrodes at three different temperatures (25, 40 and 55 °C) in order to find the most favorable electrochemical conditions. The pristine CP displayed robust electrochemical performance for up to 200 repetitive CV cycles while the Pt loaded electrode’s performance was stable for only 70 cycles, even though the latter exhibited a more reversible behavior, moving from a quasi-reversible to a reversible system ( D ox. = 4.0 × 10 −6 cm 2 s −1 and D red. = 2.5 × 10 −6 cm 2 s −1 ). The In and La metal modified electrodes did not show any improvement with regard to the kinetics or reversibility of the reaction. The addition of 1 M H 2 SO 4 to the base electrolyte enhanced the cerium reduction reaction by a factor of 3, ( −7.2 × 10 −3 A cm −2 ). The highest exchange current densities (j o ) were achieved at 40 °C for the CP-Pt (1 × 10 −3 A cm −2 ) attributable to the presence of the catalytic Pt. Elevated temperatures (40 and 55 °C) improved D and ΔE p. while also the mass transport parameters a) dynamic viscosity (∼1.5 mPa·s) and b) electrolytic conductivity (∼265 mS cm −1 ) of the Ce(III)/(IV) half-cell reaction. Overall, pristine CP and to a lesser extent CP-Pt demonstrated good stability with prolonged cycling and kinetics comparable with the ones of Pt and Pt based electrodes. [ABSTRACT FROM AUTHOR]

Conventional platinum (Pt) or emerging materials for the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs) have been fabricated on a fluorine-doped tin oxide (FTO) substrate. In this study, carbon paper with three-dimensional (3D) carbon fiber networks, which is highly porous, but has sufficient space for efficient transportation of electrolytes, is used in replace of the conventional heavy, rigid and expensive FTO/glass substrate in DSSC CEs. To prove the advantages of these highly conductive carbon paper electrodes, a thin poly(3,4-ethylenedioxythiophene) (PEDOT) film is uniformly coated on the surface of 3D carbon paper via a chemical polymerization method. The catalytic properties of the PEDOT/carbon paper as the CE in a DSSC are studied using cyclic voltammetry,J-V, and IPCE measurements. Interestingly, the PEDOT/carbon paper CE exhibits better functionality as a CE for tri-iodide reduction as compared to conventional Pt/FTO-based CEs. The controlled DSSC with a PEDOT/carbon paper CE exhibits a power conversion efficiency of 8.05% under 100 mW·cm-2illumination, which is higher than that of conventional DSSCs with standard Pt/FTO CEs (7.41%). [ABSTRACT FROM AUTHOR]

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

Abstract: Pd nanostructured catalysts were electrodeposited by surface-limited redox replacement reactions using the electrochemical atomic layer deposition technique. Carbon paper and Ni foam were used as substrates for the electrodeposition of the metal. Supported nanostructured Pd electrodes were characterized using electrochemical methods and scanning electron microscopy. Carbon paper and Ni foam produced good quality deposits with some agglomeration on Ni foam. The EDX profiles confirmed the presence of Pd particles. Cyclic voltammograms of the electrodeposited Pd on substrates showed features characteristic of polycrystalline Pd electrodes. In the acidic electrolyte a very weak oxygen reduction reaction (ORR) activity was observed on Pd/Carbon paper electrode when compared to Pd/Ni foam electrode. The Pd/Ni foam electrode showed improved ORR activity in alkaline medium. [Copyright &y& Elsevier]

Highlights: [•] Bubble formation is dependent on pore size and the receding contact angle of the GDL. [•] Larger bubbles form on carbon cloth than carbon paper GDL due to different wettability. [•] Gas flows laterally through the porous GDL to existing large bubbles. [•] Fuel cell performance is reduced by large bubbles in the flow channel. [•] Gas may be collected in dedicated channels creating a ‘bubble-free’ flow field design. [ABSTRACT FROM AUTHOR]

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

• The desired N(CH3)4V8O20 material, N(CH3)4+ of which exclusively acts as structural pillar, was firstly synthesized by facile one-step hydrothermal method and applied in AZIBs. • The N(CH3)4+ as structural pillar not only amplifies the interlayer spacing of 11.5 Å but also enhances structure stability, which actually optimizes the electrochemical performance overall. • The hierarchy distributive Zn anode grown on carbon paper with 3D braid architecture has proved effective. • It delivers a high capacity of 360 mAh g − 1 at 0.5 A g − 1 and capacity retention 97% after 5000 cycles at 50 A g − 1 with capacity of 105 mAh g − 1. Vanadate based cathode materials have been enormously investigated into aqueous zinc-ion batteries (AZIBs) in current research due to high specific capacity and large layer spacing that can accommodate sufficient ions. However, bulk vanadate based cathode materials suffer from a rapid capacity decaying as a result of low electronic conductivity, inferior ion diffusion kinetics and unstable structure during the zinc ion de/intercalation. Meanwhile, the inescapable zinc dendrite formation and reactive irreversibility during long cyclic testing also lead to growing polarization and poor cyclic performance. Herein, we put forward a strategy of structural design by synergistically introducing quaternary ammonium cation within vanadium bronze structure. The desired N(CH 3) 4 V 8 O 20 material, pure monomorph phase, was firstly synthesized by facile one-step hydrothermal method, which owns lattice spacing of 11.5 Å and stable crystalline structure for faster kinetics, higher capacity and better cyclic stability. Combined with the optimized 3D braid architecture of Zn@carbon paper anode, the as-obtained AZIBs exhibit a high capacity of 360 mAh g −1 at 0.5 A g −1. While the current density raises to 100 folds from 0.5 A g −1 to 50 A g −1, appreciable capacity of 105 mAh g −1 and outstanding stability of ultra-long lifespan with capacity retention 97% after 5000 cycles are achieved. Combining the sound investigations of experimental practices and computational research, mechanism of rapid and stable Zn2+ storage was systemically demonstrated. The optimized electrochemical performance could be attributed to highly reversible ion de/intercalation, superior ion diffusion kinetics and no side reactions. This work leads to a new strategy of the design for cathodes in AZIBs and unfolds a new path for the actualization of high-up vanadate based materials. [Display omitted] [ABSTRACT FROM AUTHOR]

• An all-solid-state thin-layer laminated cell realized calibration-free coulometric determination of K+ ions. • The cell achieved complete mass transport of the target ion from a 1 mm3 drop of the aqueous sample. • An originally prepared conducting-polymer-dispersed ink was cast on the carbon electrode. • The cell allows the calibration-free determination of K+ ions in a 1 mm3 drop of ten-fold-diluted serum. Calibration-free coulometric determination of K+ ions was realized using an all-solid-state thin-layer laminated cell with a simple laminate structure. The fabricated cell consists of a Ag/AgCl electrode, a plastic spacer for positioning the aqueous sample solution, an organic ion-selective membrane, and a conducting polymer/carbon electrode. An originally prepared conducting-polymer-dispersed ink was cast on a conductive carbon sheet (a screen-printed graphite electrode or carbon paper) to fabricate the conducting polymer/carbon electrode. The cell achieved complete mass transport of the target ion from a 1 mm3 drop of the aqueous sample to the organic ion-selective membrane under a constant potential between the Ag/AgCl electrode and the conducting polymer/carbon electrode, which generated electrical current for enabling the ion transfer. The electric charge obtained by integrating the electric current was used to estimate the molar amount of the target ion in the sample drop. For tetraethylammonium cations (TEA+; 20–200 μmol dm−3), the evaluated molar amounts corresponded to 92%–94% of the initial mole amounts. The repeatability estimated using the same cell was ±4%–6%, and the device-to-device reproducibility was ±4% for five cells. In terms of K+-ion detection (0.1–0.8 mmol dm−3) in sample drops containing NaCl (14 mmol dm−3), the evaluated molar amounts corresponded to 86%–92% of the initial molar amounts, indicating the promise of the all-solid-state thin-layer laminated cell for achieving the calibration-free determination of K+ ions in a 1 mm3 drop of ten-fold-diluted serum. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Multi-walled carbon nanotubes grown on the carbon paper substrate are prepared by in situ growth in a chemical vapor deposition system. Co(OH)2 is deposited on carbon nanotubes/carbon paper by electrodeposition methods. SEM images show that the successful growth of nanometer-sized Co(OH)2 nanosheets on the surface of carbon nanotubes/carbon paper substrate. The electrodes of Co(OH)2/carbon nanotubes/carbon paper composite are investigated for their use in supercapacitors with cyclic voltammograms, chronopotentiometric measurements and electrochemical impedance spectroscopy. The composite electrode shows the largest specific capacitance of 1083Fg−1 at a current density of 0.83Ag−1 in 6M KOH electrolyte. Furthermore, this composite exhibits good cycling stability and lifetime. The implanted CNTs between carbon paper and Co(OH)2 act as a good conductive medium for electrodes in supercapacitors, and the interconnected nanosheets of the Co(OH)2 can facilitate the contact of the electrolyte with active materials, and thus increase the capacitance. [Copyright &y& Elsevier]

Abstract: The surface structure of the commercial carbon paper (CP) has been modified through thermal treatment, and then MnO2 was electrodeposited on the thermally-treated carbon paper (TTCP) by cyclic voltammetry (CV) method in the phosphate buffer solution (PBS, pH 9.18) containing KMnO4. The obtained samples were characterized by X-ray diffraction (XRD), X-ray photoelectron energy spectroscopy (XPS) and scanning electron microscopy (SEM). The results showed that the phase of the obtained MnO2 was amorphous, and that the morphology of the MnO2 deposited on the substrates was influenced strongly by the substrates. The capacitive properties of MnO2 deposited on the carbon substrates were investigated by CV, galvanostatic charge/discharge, electrochemical impedance spectroscopy technique. It was found that the specific capacitance of MnO2 deposited on the optimum TTCP can reach to 749Fg−1 based on the charge/discharge measurement, which was far larger than that on the CP (345Fg−1). [Copyright &y& Elsevier]

Abstract: Carbon-supported PdP nanocatalysts, with 15at.% P, were directly deposited onto a gas diffusion layer (carbon paper with Teflon) by electroless deposition. The electrochemical activity of the catalysts was determined in sulfuric acid solution with and without methanol. PdP alloys show a higher oxygen reduction reaction (ORR) activity than Pd, but comparable to that of Pt. Additionally, PdP catalysts have significantly higher catalytic activity for the ORR at high concentration of methanol. Rotating disk electrode (RDE) analysis revealed that the ORR on PdP catalyst follows the four-electron pathway. The catalysts were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. [Copyright &y& Elsevier]

Abstract: Accuracy in the effective diffusion coefficient of the gas diffusion layer (GDL)/microporous layer (MPL) is important to accurately predict the mass transport limitations for high current density operation of polymer electrolyte membrane (PEM) fuel cells. All the previous studies regarding mass transport limitations were limited to pure GDLs, and experimental analysis of the impact of the MPL on the overall diffusion in the porous GDL is still lacking. A modified Loschmidt cell with an oxygen–nitrogen mixture is used in this work to determine the effect of MPL on the effective diffusion coefficients. It is found that Knudsen effects play a dominant role in the diffusion through the MPL where pore diameters are less than 1μm. Experimental results show that the effective diffusion coefficient of the MPL is only about 21% that of its GDL substrate and Knudsen diffusion accounts for 80% of the effective diffusion coefficient of the GDL with MPL measured in this study. No existing correlations can correlate the effective diffusion coefficient with significant Knudsen contribution. [Copyright &y& Elsevier]

Abstract: The electrochemical removal of bromate ions was performed with BDD electrodes in a two-compartment electrolytic reactor. Bromate ions removal and the production of Br− were observed and determined. The removal of bromate ions occurred at an applied bias potential of −0.45V (vs. SCE). And, the removal rate increased with the applied bias potential. Within 2h, nearly 90% of bromate ions were removed with the applied bias potential of −1.0V (vs. SCE). Effect of pH on bromate ions removal was slight. SO4 2− and Cl− ions inhibit the electrochemical reduction of bromate ions, which can be explained by the competitive adsorption of coexisting anions at the electrode surface with the bromate ions. In comparison, the graphite and carbon paper electrode exhibit low catalytic activities toward reduction removal of bromate ions under the same experimental conditions. A possible reason was proposed. [Copyright &y& Elsevier]

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

Abstract: Gaseous oxidation of carbon papers (CPs) decorated with carbon nanotubes (CNTs) with varying degrees of oxidation was conducted to investigate the influence of surface oxides on the performance of electrochemical capacitors fabricated with oxidized CNT/CP composites. The oxidation period was found to significantly enhance the O/C atomic ratio on the composites, and the increase in oxygen content upon oxidation is mainly contributed by the formation of Cx2013;O groups. The electrochemical behavior of the capacitors was tested in 1M H2SO4 within a potential of 0 and 1V vs. Ag/AgCl. Both superhydrophilicity and specific capacitance of the oxidized CNT/CP composites were found to increase upon oxidation treatment. A linearity increase of capacitance with O/C ratio can be attributed to the increase of the population of surface oxides on CNTs, which imparts excess sites for redox reaction (pseudocapacitance) and for the formation of double-layer (double-layer capacitance). The technique of ac impedance combined with equivalent circuit clearly showed that oxidized CNT/CP capacitor imparts not only enhanced capacitance but also a low equivalent series resistance. [Copyright &y& Elsevier]

Abstract: Gas diffusion layers (GDLs) were fabricated using non-woven carbon paper substrates with various thicknesses developed by Hollingsworth & Vose Co. Highly consistent carbon slurry containing Pureblack carbon and vapor grown carbon fiber (3:1 ratio) with 25wt.% Teflon was prepared by using a dispersion agent, Novec-7300 in isopropyl alcohol. Micro-porous layer was coated by using a fully automated Coatema coating tool with a uniform carbon loading of 2.6–3mgcm−2 using carbon slurry. The surface morphology, contact angle and pore size distribution of the GDLs were examined using SEM, Goniometer and Hg Porosimeter, respectively. Various cathode GDLs assembled into MEAs were evaluated in a single cell PEMFC under various operating relative humidity (RH) conditions using H2/O2 and H2/air as reactants. The peak power density of the single cell using the optimum carbon paper substrate thickness was about 1400 and 700mWcm−2 with H2/O2 and H2/air at 60% RH, respectively. It was found that the pore diameter as well as the corresponding pore volumes of the GDLs played a key role in exhibiting the optimum fuel cell performance. [Copyright &y& Elsevier]

• 3D integrated Sn/CNT@N C gas diffusion electrode is proposed by phase inversion. • CNT@N C has integrated sponge-like microporous and finger-like macroporous layers. • The co-catalysis of N improves electron-proton-gas transfer for high performance. • Faraday efficiency of formate and CO is improved compared with Sn/carbon paper. A 3D integrated hierarchical porous N-doped Sn/CNT@N C gas diffusion electrode is proposed via phase inversion to synergistically improve electron-proton-gas transfer and efficiency of CO 2 reduction reaction (CO2RR). Hierarchical porous structure is tuned by the carbon nanotube additive during phase inversion, which integrates microporous layer and diffusion layer to decrease mass transfer resistance comparing with the 2D layer structure of commercial carbon paper. XPS results show that Sn/CNT@N C 800 contains pyridinic nitrogen and pyrrolic nitrogen with catalytic activity. EIS and LSV curves show that Sn/CNT@N C 800 is beneficial to reduce mass transfer resistance and increase current density after twice hydrophobic treatments. As a result, Sn/CNT@N C 800 shows higher CO 2 RR electrocatalytic activity. The reaction rate and Faraday efficiency of CO at 12 mA cm−2 increase by 40.2% and 40.6%, respectively compared with Sn/carbon paper. The reaction rate and Faraday efficiency of formate are also slightly higher than those of Sn/carbon paper. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel hydrogen ion supercapattery was assembled. • N and P co-doped carbon paper was effectively acted as the cathode substrate. • The cyclic stability could be improved by modifying the cathode with Nafion. Hydrogen ion battery is a promising energy storage device due to its advantages of non-pollution, excellent rate capability and feasibility at low temperature. Herein, we assemble a novel rechargeable hydrogen ion supercapattery with the iodine-absorbed carbon paper doped with N and P (I 2 -NP-CP) as the cathode electrode and molybdenum trioxide as the anode electrode. Typically, the I 2 -NP-CP electrode shows the superior rate capability from 1 A g−1 (174.7 mAh g−1, 483.8 F g−1) to 20 A g−1 (111.1 mAh g−1, 307.7 F g−1), mainly ascribed to the strong interaction between iodine and the NP-CP substrate. Furthermore, electrochemical measurement of the I 2 -NP-CP@Nafion//MoO 3 supercapattery manifests that the electrodes exhibit excellent cycling stability, retaining 124.3 mAh g−1 after 500 cycles at 15 A g−1, accounting for 93.2 % of the initial capacity. Although some IO 3 − dissolves in the electrolyte due to the weak chemical interaction between IO 3 − and NP-CP, and cannot be completely reduced to I− during discharge process, it can be improved by modification of electrode with Nafion resin to further better the cycling stability. The excellent electrochemical properties in this study show the possibility for the development of novel rechargeable hydrogen ion supercapattery system. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Porous conducting carbon paper with its unique combination of properties acts as the backing material of electrode in a fuel cell. It not only assists in the flow of electrons and reactant gases but also acts as an effective support for the electrolyte and the catalyst layer. The electrically conducting porous carbon paper was prepared by adopting a modified process of preparation which involves molding together several carbon fiber preforms in the form of laminates rather than a single preform. The method was found to influence the characteristics of the paper significantly and resulted in improved performance of the unit fuel cell employing the laminated paper as electrode. The I–V performance of the fuel cell using carbon paper formed by molding single ply showed a peak power density of 573mW/cm2 as compared to that of 722mW/cm2 for three ply laminates, a value very close to that of achieved by using Toray (Japan) carbon paper (782mW/cm2) under identical operating conditions. [Copyright &y& Elsevier]