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This research introduces the design of a gas-diffusional cathode employing bilirubin oxidase (BOx) immobilized on a complex matrix composed of carbon nanotube (CNT) modified Toray paper (TP) and, encapsulated in silica-gel. The developed enzymatic cathode consists of two layers. One is the hydrophobic gas-diffusional layer (GDL) and the other a hydrophilic catalytic layer (CL) which were combined by pressing at 1000 psi for five minutes. The GDL (35% weight teflonized Vulcan carbon powder (XC35)) that is exposed to air has hydrophobic and porous properties that facilitate oxygen diffusion. The CL consists of a thin, high surface area, 3D CNT/silica-gel matrix where the 3D-enzymatic structure is immobilized and preserved. The nanostructured architecture of the CL was designed to improve conductivity and surface area. Such a design was achieved by modifying the TP surface with CNTs. CNTs are grown on TP by chemical vapor deposition which is possible by electrodepositing Ni seeds via pulse chronoamperometry. Entrapment of BOx was achieved by using tetramethyl orthosilicate (TMOS), a highly volatile compound that results in a polymeric condensation reaction with H2O at room temperature. TMOS polymerization of the cathode surface was performed in a chemical vapor deposition process to form a silica-gel matrix. The gas diffusional cathode was assembled to a capillary driven microfluidic system to be electrochemically characterized. The characterization was performed from electrolyte pH 5 to pH 8 with increments 0.5 in pH. The best performance was observed at pH 5.5 showing a current output of 655.07 ± 146.18 µA.cm-2 and 345.36 ± 30.04 µA.cm-2 at 0 V and 0.3 V, respectively. At a pH of 7.5 the current generated was 287.05 ± 20.37 µA.cm-2 and 205.37 ± 1.57 µA.cm-2 at 0 V and 0.3 V, respectively. The results show the stability of the enzymatic structure, subject to various pH, is maintained within the 3D-CNT silica-gel matrix for pH lower than 8. Future work will focus on storage life and stability over time. [ABSTRACT FROM AUTHOR]

This paper describes the design and testing of a microfluidic biofuel cell that uses a flow-through bioanode and an air-breathing cathode. The bioanode is Toray carbon paper with glucose dehydrogenase (GDH), multi-walled carbon nanotubes (MWCNTs), and methylene green immobilized within a hydrogel. The cathode consists of a commercially available air-breathing platinum cathode hot pressed to a Nafion membrane. All remaining biofuel cell components were laser-cut from poly(methyl methacrylate) (PMMA) and silicone sheets. Half-cell experiments indicate that cathode variability limits the biofuel cell. An examination of flow rate effects on the biofuel cell showed that the current density increased sharply up to about 1 mL/min. Tested at this flow rate, the flow-through biofuel cell achieved a maximum current and power density of 705 µA/cm² and 146 µW/cm². This was a 6% and 29% improvement in the current and power density, respectively, compared to the previously demonstrated bioanode without flow. Fuel utilization was calculated based on the measured current and by measuring UV-Vis absorbance of the reduced form of hydroxybenzhydrazide. The maximum fuel utilization was 5.8% at a flow rate of 0.05 mL/min. Finally, a numerical model of the biofuel cell was designed and its results compare favorably to actual data. [ABSTRACT FROM AUTHOR]

Abstract Aiming to advance the technical maturity of CO2 electrolysis to formic acid, various gas diffusion layers (GDLs) are investigated for their suitability as carbon‐based substrate for gas diffusion electrodes (GDEs) and their effect on the electroreduction of CO2 to formate. Particular attention lies on the elucidation for the effect of the GDL thickness, hydrophobic treatment, and presence of a microporous layer (MPL) on the GDE performance in terms of Faradaic efficiency. Based on the investigation it is found that the GDL thickness has no discernible influence on the Faradaic efficiency, while a GDE with a hydrophobic treatment of 10 % PTFE outperforms a GDE based on a GDL with 30 % PTFE. Furthermore, the presence of a MPL is found to be of marked importance to achieve relevant current densities given its effect on the focus of the catalyst layer on the GDE surface after spray coating, the wetting, and the electrical conductivity.

Ammonia (NH3) is one of the most used chemicals. Industrially, ammonia is produced by hydrogenation of N2 through the Haber–Bosch process, a process in which enormous amounts of CO2 are released and requires a huge energy consumption (~ 2% of the total global energy). Therefore, it is of paramount importance to explore more sustainable and environmentally friendly routes to produce NH3. The electrochemical nitrogen reduction reaction (NRR) to ammonia represents a promising alternative that is receiving great attention but still needs to be significantly improved to be economically competitive. In this work, the NRR is studied on Pt–Rh nanoparticle–based electrodes. Carbon-supported Pt–Rh nanoparticles (2–4 nm) with different Pt:Rh atomic compositions were synthesized and subsequently airbrushed onto carbon Toray paper to fabricate electrodes. The electrochemical NRR experiments were performed in a H-cell in 0.1 M Na2SO4 solution. The results obtained show interesting faradaic efficiencies (FE) towards NH3 which range between 5 and 23% and reasonable and reliable NH3 yield values of about 4.5 µg h−1 mgcat−1, depending on the atomic composition of the electrocatalysts and the metal loading. The electrodes also showed good stability and recyclability (constant FE and NH3 yield in five consecutive experiments). Pt–Rh nanoparticle–based electrodes were employed for the NRR to NH3 in 0.1 M Na2SO4. Interesting FE towards NH3 and reasonable and reliable NH3 yield values were observed depending on atomic composition and metal loading. Good stability and recyclability (constant FE and NH3 yield in five consecutive experiments) were also observed. [ABSTRACT FROM AUTHOR]

Biological compounds like Dopamine (D), Xanthine (X), Ascorbic acid (AA) and Uric acid (UA) play a vital role in food, clinical and human metabolism. Since these compounds are present in biological fluids and have close standard potentials values, it is imperative to choose a method to sense these fluids without any electrochemical interference. Toray paper, with a porous gas diffusion layer imbibed with denser carbon fibers, is an excellent option that can be utilized as a working electrode for such sensing applications. Herein, the electroactivity of these compounds was tested using cyclic voltammetry and square wave voltammetry without any interference. The linear ranges for the compounds (D, X, AA, UA) are 10- $1000~\mu \text{M}$ , 7- $300~\mu \text{M}$ , 100- $1000~\mu \text{M}$ and 30- $1000~\mu \text{M}$ respectively, while the limits of detection are $9.67~\mu \text{M}$ , $6.54~\mu \text{M}$ , $97.12~\mu \text{M}$ and $28.74~\mu \text{M}$ respectively with S/N ratio of 1.5. Finally, the electrode was tested with human serum samples for the identification of D, X, AA and UA manifesting exceptional reproducibility. [ABSTRACT FROM AUTHOR]

Abstract  Biofuel cells have a tremendous opportunity to provide much higher energy densities and smaller footprints than batteries for powering implantable medical devices, leading to less intrusive implantable devices with longer lifetimes. This paper introduces biofuel cell anode and cathode designs based on mediated glucose oxidation by glucose oxidase and oxygen reduction by bilirubin oxidase, respectively. We report here the progress toward the development of components for biofuel cells working in physiological conditions. We have investigated enzymatic electrode formulations that have the potential to achieve higher current densities and longer stability of the electrodes: (a) high surface area by the use of multiscale carbon materials, (b) immobilization of redox mediator on the electrode surface, and (c) use of a protective biocompatible polymer coating. [ABSTRACT FROM AUTHOR]

An efficient immobilization of Glucose oxidase (GOx) on an appropriate substrate is one of the main challenges of developing fuel cells that allow energy to be obtained from renewable substrates such as carbohydrates in physiological environments. The research importance of biofuel cells relies on their experimental robustness and high compatibility with biological organisms such as tissues or the bloodstream with the aim of obtaining electrical energy even from living systems. In this work, we report the use of 5,10,15,20 tetrakis (1-methyl-4-pyridinium) porphyrin and glutathione capped CdTe Quantum dots (GSH-CdTeQD) as a support matrix for the immobilization of GOx on carbon surfaces. Fluorescent GSH-CdTeQD particles were synthesized and their characterization by UV-Vis spectrophotometry showed a particle size between 5–7 nm, which was confirmed by DLS and TEM measurements. Graphite and Toray paper electrodes were modified by a drop coating of porphyrin, GSH-CdTeQD and GOx, and their electrochemical activity toward glucose oxidation was evaluated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Additionally, GOx modified electrode activity was explored by scanning electrochemical microscopy, finding that near to 70% of the surface was covered with active enzyme. The modified electrodes showed a glucose sensitivity of 0.58 ± 0.01 μA/mM and an apparent Michaelis constant of 7.8 mM. The addition of BSA blocking protein maintained the current response of common interferent molecules such as ascorbic acid (AA) with less than a 5% of interference percentage. Finally, the complex electrodes were employed as anodes in a microfluidic biofuel cell (μBFC) in order to evaluate the performance in energy production. The enzymatic anodes used in the μBFC allowed us to obtain a current density of 7.53 mAcm−2 at the maximum power density of 2.30 mWcm−2; an open circuit potential of 0.57 V was observed in the biofuel cell. The results obtained suggest that the support matrix porphyrin and GSH-CdTeQD is appropriate to immobilize GOx while preserving the enzyme's catalytic activity. The reported electrode arrangement is a viable option for bioenergy production and/or glucose quantification. [ABSTRACT FROM AUTHOR]

Electron mediation between NAD-dependent enzymes using quinone moieties typically requires the use of a diaphorase as an intermediary enzyme. The ability for a naphthoquinone redox polymer to independently oxidize enzymatically-generated NADH is demonstrated for application to glucose/O2 enzymatic fuel cells. [ABSTRACT FROM AUTHOR]

This work presents the construction and evaluation of a membraneless nanofluidic fuel cell made with fiberglass using flow-through porous electrodes based on Toray paper, coupled with a microelectronic interface to supply energy to low-power demand applications. The device performance is optimized for different operating conditions related with flow rate, stoichiometry and concentration and employing formic acid as fuel. Evaluation tests were performed with a homemade testing station using a commercial varying resistance. [ABSTRACT FROM AUTHOR]

The pressing demand for more sustainable energy provision and the ongoing transition toward renewable resources underline the critical need for effective energy storage solutions. To address this challenge, scientists persistently explore new compounds and hybrids and, in such a dynamic research field, 2D materials, particularly transition metal di‐chalcogenides (TMDCs), show great potential for electrochemical energy storage uses. Simultaneously, also conductive polymers (CPs) are interesting and versatile supercapacitor materials, especially polyaniline (PANI), which is extensively studied for this purpose. In this work, a powerful method to combine TMDCs and PANI into covalently grafted hybrids starting from aniline functionalized few‐layers 1T‐MoS2, attained by a facile direct arylation with iodoaniline, is presented. The hybrids provide circa 70 F g−1 specific capacitance in a pseudo device setup, coupled with a robust capacitance retention of well over 80% for up to 5000 cycles. These findings demonstrate the potential of similar covalent composites to work as active components for novel, innovative energy storage technologies. At the same time, the successful synthesis marks the efficacy of direct covalent grafting of conductive polymer on the surface of 2D TMDCs for stable functional materials. [ABSTRACT FROM AUTHOR]

Impaired power quality is known to increase the power consumption of water electrolysis cells without affecting the hydrogen production rate. Owing to a lack of large‐signal dynamic water electrolyzer models, simulations on the topic often consider only the static polarization curve omitting actual cell dynamics. This article aims to bridge the gap by experimentally studying the dynamic phenomena leading to additional power consumption of a polymer electrolyte membrane water electrolyzer cell using sinusoidal current ripple. The effect of ripple amplitude is analyzed with high‐speed current and voltage waveform measurements, and the frequency dependence is determined using electrochemical impedance spectroscopy. The complex cell impedance is found to be the only parameter needed for determining the additional power consumption at frequencies above 30Hz$30 \,\mathrm{Hz}$. This finding enables a simple prediction of additional power consumption for arbitrary current waveforms at frequencies relevant for water electrolyzer rectifiers. At frequencies below 30Hz$30 \,\mathrm{Hz}$, the static polarization curve begins to influence the voltage waveform of the specific cell, thereby reducing the predictive power of the impedance model. The results prove the use of the static polarization curve is generally inaccurate for modeling water electrolysis power consumption with ripple current. [ABSTRACT FROM AUTHOR]

3D printing technology based electrochemical device can provide ease of fabrication, cost effectiveness, rapid detection and lower limit of detection. Herein, a novel, customized, portable and inexpensive 3D printed electrochemical device, has been presented. Fibrous carbon Toray paper, deposited with gold nanoparticles through electrodeposition, used as a working electrode which Further device was tested with 1 mM sodium hypochlorite using cyclic voltammetry (CV) and square wave voltammetry (SWV) in 0.1 M PBS. Hypochlorite has a pivotal role in supporting the growing chemical and paper industries and finds diverse uses in several clinical applications. It is primarily used for disinfecting food, water and surfaces. The scan rate study was carried out from 20 mVs−1 to 250 mVs−1 using cyclic voltammetry technique. The diffusion coefficient obtained from scan rate effect was 1.39 × 10−6 cm2s−1. The concentration range was evaluated with SWV technique, in a linear range of 0.6 μM–40 μM, with a detection limit of 0.7 μM. The device was further analyzed to ensure non-interference from co-existing chemicals like sodium chloride, potassium nitrate, sodium carbonate, sodium nitrite. Real sample analysis was done with sea, artificial sea and tap water with impressive recovery values. In summary, the developed working electrode can be customized and modified based on testing analyte; thus, the proposed device can be used for various other biochemical analytes. [Display omitted] • Miniaturized 3D printed electroanalytical device was fabricated. • Gold nanoparticles were electrodeposited on Toray paper used as working electrode. • 1 mL of the sample was used throughout all analysis. • Lower limit of detection 0.07 μM was obtained using the device. • Hypochlorite detection in sea, artificial sea and tap water samples was carried out. [ABSTRACT FROM AUTHOR]

The microporous layer (MPL) and the gas diffusion layer (GDL) in a polymer electrolyte membrane (PEM) fuel cell assembly are often treated as separate layers in the literature. However, there exists a considerable third region where the two different materials merge in the coating process. This region has properties that differ from either of the materials that it consists of. Through-plane thermal conductivity and thickness variation under different compaction pressures were measured for such a composite region of two different commercial GDLs, Freudenberg H1410 and Toray Paper TGP-H-030, each treated with a custom-made MPL ink. Thermal conductivity at 15 bar compaction pressure for untreated Freudenberg H1410 GDL is 0.124 ± 0.009 W K-1 m-1 and for the custom-MPL-coated Freudenberg H1410 materials it was increased by the treatment to 0.141 ± 0.004 W K-1 m-1 and 0.145±0.004WK-1 m-1 for 9.9 wt% and 11.9 wt% ink, respectively. For Toray paper TGP-H-030 the thermal conductivity at 15 bar compaction pressure for GDL only is 0.449 ± 0.009WK-1 m-1 and for the custom-MPL-coated Toray TGP-H-030 materials it was decreased by the treatment to 0.39 ± 0.05 W K-1 m-1 and 0.39 ± 0.00 W K-1 m-1 for 9.9 wt% and 11.9 wt% ink, respectively. [ABSTRACT FROM AUTHOR]

Carbon Papers (CPs) have been widely used as a Gas Diffusion Layer (GDL) for high performance fuel cells. Herein we report a novel method for production of GDL, without the need to carbonization and graphitization steps that is common steps in GDL production. CP is provided by a dry-laying of carbon fibers (CFs) and expanded graphite (EG) in the phenolic resin and the composites are compared with carbon paper of Toray Co., Ltd. The effect of paper thickness, aspect ratio of CF and EG value of the composite are investigated. The characterizations are performed by scanning electron microscope, maximum pore size, mean pore size, permeability, electrical conductivity, flexibility, and performance (I-V) curve. The results shown that in the optimized state of the composition in the manufactured composite, the values of mean pore size, permeability, electrical conductivity, and performance curve is reasonable and near the Toray paper, however the manufactured composite show a much higher flexibility than that of Toray paper in a qualitative test. In addition, due to removing the graphitization and carbonization steps for production of carbon paper, the produced carbon paper costs are much lower than Toray paper. [ABSTRACT FROM AUTHOR]

The increasing demand in healthcare for accessible and cost-effective analytical tools is driving the development of reliable platforms to the customization of therapy according to individual patient drug serum levels, e.g. of anti-psychotics in schizophrenia. A modifier-free microfluidic paper-based electroanalytical device (μPED) holds promise as a portable, sensitive, and affordable solution. While many studies focus on the working electrode catalysts, improvements by engineering aspects e.g. of the electrode arrangement are less reported. In our study, we demonstrate the enhanced capabilities of the 3D electrode layout of μPED compared to 2D μPED arrangements. We especially show that screen printing can be employed to prepare 3D μPEDs. We conducted a comparison of different 2D and 3D electrode arrangements utilizing cyclic voltammetry in [Fe(CN)6]3−/4−, along with square-wave voltammetry for clozapine (CLZ) sensing. Our findings reveal that the utilization of the 3D μPED leads to an increase in both the electrochemically active surface area and the electron transfer rate. Consequently, this enhancement contributes to improve sensitivity in the CLZ sensing. The 3D μPED clearly outperforms the 2D μPED arrangement in terms of signal strength. With the 3D μPED under the optimized conditions, a linear dose–response for a concentration range from 7.0 to 100 μM was achieved. The limit of detection and sensitivity was determined to be 1.47 μM and 1.69 μA μM−1 cm−2, respectively. This evaluation is conducted in the context of detection and determination of CLZ in a human blood serum sample. These findings underscore the potential of the 3D μPED for future applications in pharmacokinetic analyses and clinical tests to personalize the management of schizophrenia. [ABSTRACT FROM AUTHOR]

Significant research endeavors have been dedicated to the search for highly efficient and cost-effective hydrogen evolution reaction (HER) electrocatalysts. Due to their unique chemical structure and physical properties, bulk tungsten disulfide (WS2) and its nanostructures are renowned electrocatalysts. This study reports a new modification method for the WS2 nanotubes (NTs) surface through cold radiofrequency plasma. The effect of two plasmatic ions, i.e., D2 and Ar, on WS2 NTs has been investigated. When applied separately, both Ar and D2 plasma-treated WS2 nanotubes improved their electrocatalytic performances, yielding overpotentials of 348 and 343 mV at −10 mA cm−2, respectively, compared to 567 mV of the untreated WS2 nanotubes. Furthermore, combined plasma treatment by using Ar and D2 plasma notably decreased the overpotential to 264 mV. The phenomenology behind inducing the surface conditions of the synergetic plasma treatment is discussed in the paper. [ABSTRACT FROM AUTHOR]

This work presents the integration of a paper-based microfluidic fuel cell inside a lateral flow assay-human immunodeficiency virus (HIV) test. To modify the HIV test, a bioanode that oxidizes the glucose present in a serum or blood sample and a cathode that reduces the oxygen delivered from air were stacked on the bottom and top, respectively, of a paper-strip test. A mixture of glucose oxidase enzyme, Nafion ® , glutaraldehyde, deionized water and tetrabutylammonium bromide were deposited on a methylene blue electro-polymerized Toray ® paper and used as the bioanode. Meanwhile, Pt/C (Vulcan XC-72) on Toray ® paper was used as an air-breathing cathode. The GOx enzyme anchored on the carbon-based surface was examined by scanning electron microscopy. The electrochemical response of the bioanode array demonstrated the oxidation of 0.1 M glucose, leading to a current density increase due to FAD + /FADH reactions. The above procedure was corroborated through scanning electrochemical microscopy, which showed an increase in the current (400 pA) in the presence of glucose on the bioanode. The paper-based microfluidic fuel cell performance showed power densities of 0.16 and 0.12 mW cm −2 using human serum and blood samples, respectively. Furthermore, the stability of the device was measured in terms of the recovery after obtaining four polarization curves that lasted 30 min, after which the sample dried out. This work represents a great advancement in the integration of a paper-based microfluidic fuel cell towards autonomous lateral flow assays. [ABSTRACT FROM AUTHOR]

A wide range of carbon nanofiber (CNF) mats with controlled properties of fiber diameter, surface area, porosity, and conductivity were fabricated via a facile and economical electrospinning method. CNFs are used as supports for bioelectrodes to enhance enzyme utilization. This study employed glucose oxidase (GOx) in a redox hydrogel system, which mediates electron transfer via osmium metal center, to create a glucose bioelectrode. CNFs reduces the hydrogel thickness and enhances the electron transport. CNFs exhibit promising glucose oxidation current density reaching 10 mA cm that is higher than those of commercial carbon materials such as multiwalled carbon nanotubes (MWCNT), Bucky paper, Pyrograf, and Toray paper. [ABSTRACT FROM AUTHOR]

Twenty two carbon materials of different origins (e.g., graphite, graphene, carbon black, hydrochars, activated carbons, carbon nanotubes and nanofibers) and with varied physicochemical characteristics (e.g., electrical conductivity, structural order, surface functionalization, porosity) were investigated as cathodes in the electrochemical production of hydrogen peroxide. A screening of the electrocatalytic performance was carried out in 0.2 cm2 (inks casted on a glassy carbon) and 4 cm2 electrodes (Toray paper). The highest H 2 O 2 production yields were obtained for carbon nanotubes and carbon nanofibers, outperforming common carbon benchmarks for this application -i.e., carbon black, carbon felt-. Furthermore, a good catalytic activity was obtained with low-cost and disordered carbon cathodes with moderate electrical conductivity and density of structural defects (e.g., nanoporous carbons), both in terms of overall production rate, selectivity and energy consumption. Data also revealed that the H 2 O 2 production yield and the faradaic efficiency are closely related to the structural parameters of the carbon materials (i.e., density of structural defects), rather than to the electrical conductivity, composition or porous features. An A D /A G threshold value of 1.5 can be used to discriminate the electrocatalytic activity of carbon cathodes for the production of H 2 O 2 through a 2e-ORR, in terms of high production rates and good faradaic efficiencies. [Display omitted] [ABSTRACT FROM AUTHOR]

The direct electrochemical reduction of nicotinamide adenine dinucleotide (NAD+) results in various products, complicating the regeneration of the crucial 1,4‐NADH cofactor for enzymatic reactions. Previous research primarily focused on steady–state polarization to examine potential impacts on product selectivity. However, this study explores the influence of dynamic conditions on the selectivity of NAD+ reduction products by comparing two dynamic profiles with steady‐state conditions. Our findings reveal that the main products, including 1,4‐NADH, several dimers, and ADP‐ribose, remained consistent across all conditions. A minor by–product, 1,6‐NADH, was also identified. The product distribution varied depending on the experimental conditions (steady state vs. dynamic) and the concentration of NAD+, with higher concentrations and overpotentials promoting dimerization. The optimal yield of 1,4‐NADH was achieved under steady–state conditions with low overpotential and NAD+ concentrations. While dynamic conditions enhanced the 1,4‐NADH yield at shorter reaction times, they also resulted in a significant amount of unidentified products. Furthermore, this study assessed the potential of using pulsed electrochemical regeneration of 1,4‐NADH with enoate reductase (XenB) for cyclohexenone reduction. [ABSTRACT FROM AUTHOR]

In the present investigation, Cu2O-based composites were successfully prepared through a multistep method where cubic Cu2O nanoparticles (CU Cu2O) have been grown on Reduced Graphene Oxide (RGO) nanosheets. The structural and morphological properties of the materials have been studied through a comprehensive characterization, confirming the coexistence of crystalline Cu2O and RGO. Microscopical imaging revealed the intimate contact between the two materials, affecting the size and the distribution of Cu2O nanoparticles on the support. The features of the improved morphology strongly affected the electrochemical behavior of the composites, increasing the activity and the faradaic efficiencies towards the electrochemical CO2 reduction reaction process. CU Cu2O/RGO 2:1 composite displayed selective CO formation over H2, with higher currents compared to pristine Cu2O (−0.34 mA/cm2 for Cu2O and −0.64 mA/cm2 for CU Cu2O/RGO 2:1 at the voltage of −0.8 vs. RHE and in a CO2 atmosphere) and a faradaic efficiency of 50% at −0.9 V vs. RHE. This composition exhibited significantly higher CO production compared to the pristine materials, indicating a favorable *CO intermediate pathway even at lower voltages. The systematic investigation on the effects of nanostructuration on composition, morphology and catalytic behavior is a valuable solution for the formation of effective interphases for the promotion of catalytic properties providing crucial insights for future catalysts design and applications. [ABSTRACT FROM AUTHOR]

In this report, we elucidated the hydrogen evolution reaction (HER) catalytic activity of different metal-azaphthalocyanine unimolecular layer (AZUL) catalysts and compared the overpotentials in alkaline electrolyte membrane water electrolysis (AEMWE). While the overpotentials are bit higher compared to Pt/C, the system utilizing the FeAzPc-4N with Sustainion® showed a low overpotential of 2.02 V at 1.0 A/cm2 and faraday efficiency of 96.3% even among the previous alternative catalysts. It is noteworthy that the AZUL catalysts are not using precious metals and even comparing with other transition metal electrocatalysts, metal atom usage is much lower because only the single transition metal atom in the azapthalocyanine macrocycle works as a catalytic site. [ABSTRACT FROM AUTHOR]

Several commonly known physiological analytes, such as ascorbic acid (AA), dopamine (D), uric acid (UA), and xanthine (X), are known to have significant impact on human metabolism. Therefore, it is quite imperative to develop a miniaturized, multiplexed, noninterfering, and inexpensive sensing platform to monitor these compounds. Reminiscing this, herein, a miniaturized electrochemical sensing platform over a poly methyl methacrylate substrate has been depicted for specific and selective sensing of AA, D, UA, and X. First, to create three electrode zones for electrochemical sensing, three microchannels were engraved on a PMMA sheet by CO2 laser ablation process. Subsequently, these microchannels were filled with suitable electrode materials leading to a miniaturized electrochemical sensing platform. In the present article, the Toray carbon gas diffusion layer was the working electrode (WE), while screen-printed conductive carbon paste and silver chloride (Ag/AgCl) ink served as the counter electrode and the reference electrode, respectively. The electrocatalytic oxidation of these analytes exhibits an excellent electro-catalytic oxidation behavior. The effect of variable concentrations and interference from the coexisting analytes was also examined. The linear concentration ranges for these compounds (AA, D, UA, and X) under the optimized parameters were 100–1000, 40–1000, 20–1000, and 10– 100 μM, respectively, while the detection limits were 89.65, 38.94, 18.71, and 9.01 μM}correspondingly. The platform was also tested with real human serum samples. Such a multiplexed and miniaturized electrochemical sensing platform can be used in point-of-care devices for simultaneous sensing of multiple analytes. [ABSTRACT FROM AUTHOR]

Compared with previous decades, healthcare has emerged as a key global concern in light of the recurrent outbreak of pandemics. The initial stage in the provision of healthcare involves the process of diagnosis. Countries worldwide advocate for healthcare research due to its efficacy and capacity to assist diverse populations. Enhanced levels of healthcare management can be attained by the implementation of rapid diagnostic procedures and cognitive data analysis. Therefore, there is a constant need for smart therapeutics, analytical tools, and diagnostic systems to improve health and well-being. The past decade witnessed enormous growth in the sensing detection systems integrated into smartphones with printed electrodes and wearable patches for the screening of various healthcare diagnostics biomarkers and therapeutic drugs. This review focuses on the expansion of point-of-care technologies and their incorporation into a broader array of portable devices, a critical aspect in the context of decentralized societies and their healthcare systems. Discussions are broadly focused on the different sensing platforms such as solid electrodes, screen-printed electrodes, and paper-based sensing strategies for the detection of various biomarkers and therapeutic drugs. We also discuss the next-generation healthcare wearable sensing device importance and future research possibilities. Finally, the portable electrochemical sensing devices and their future perspective developments towards healthcare diagnosis are critically summarized., Competing Interests: Declarations. Ethical approval: The results/data/figures in this manuscript have been reproduced with the appropriate permissions from the publishers. Competing interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The combination of compositional versatility and topological diversity for the integration of electroactive species into high-porosity molecular architectures is perhaps one of the main appeals of metal–organic frameworks (MOFs) in the field of electrocatalysis. This premise has attracted much interest in recent years, and the results generated have also revealed one of the main limitations of molecular materials in this context: low stability under electrocatalytic conditions. Using zirconium MOFs as a starting point, in this work, we use this stability as a variable to discriminate between the most suitable electrocatalytic reaction and specific topologies within this family. Our results revealed that the PCN-224 family is particularly suitable for the electroreduction of molecular nitrogen for the formation of ammonia with faradaic efficiencies above 30% in the presence of Ni2+ sites, an activity that improves most of the catalysts described. We also introduce the fluorination of porphyrin at the meso position as a good alternative to improve both the activity and stability of this material under electrocatalytic conditions. [ABSTRACT FROM AUTHOR]

Photoelectrochemistry is used to develop solar energy technologies for fuel production and chemical transformations. Semiconductor materials such as TiO2, WO3, BiVO4, Fe2O3, and Cu2O are often investigated in devices designed to convert light energy into chemical energy, including for the production of hydrogen by photoelectrochemical (PEC) water splitting. The oxide electrodes are of significant interest due to their potential for efficient PEC reactions with high durability and their relatively low costs compared to other semiconductor materials. This review highlights the roles played by macroporous photoelectrodes in the development of highly efficient photoelectrodes and advanced PEC systems using polymer electrolytes. Three‐dimensional conductive fiber substrates, such as titanium felt and carbon paper, outperform their two‐dimensional counterparts owing to their larger interfacial areas that enhance PEC properties. The macroporous structures facilitate mass‐transport‐limited reactions when integrated with polymer electrolytes in membrane electrode assemblies. Such configurations are promising for PEC splitting of pure water, and for transforming gaseous molecules such as water vapor, volatile organic compounds, and methane. Optimizing the configuration, including electrode materials selection and ionomer‐coating treatment, can potentially improve the performance of polymer electrolyte membrane PEC cells. Porous transport photoelectrodes integrated with proton/anion‐exchange membranes offer significant opportunities for advanced PEC applications. [ABSTRACT FROM AUTHOR]

Grid-scale energy storage solutions are necessary for using renewable energy sources efficiently. A supercapattery (supercapacitor + battery) has recently been introduced as a new variety of hybrid devices that engage both capacitive and faradaic charge storage processes. Nano-chain architectures of Ni0.5Co0.5S electrode materials consisting of interconnected nano-spheres are rationally constructed by tailoring the surface structure. Nano-chains of the bimetallic sulfide Ni0.5Co0.5S are presented to have a superior charge storage capacity. The Ni0.5Co0.5S nano-chain electrode presents a capacitance of 2001.6 F g−1 at 1 mV s−1, with a specific capacity of 267 mA h g−1 (1920 F g−1) at 1 A g−1 in 4 M KOH aqueous electrolyte through the galvanostatic charge–discharge (GCD) method. The reason behind the high charge storage capacity of the materials is the predominant redox-mediated diffusion-controlled pseudocapacitive mechanism coupled with surface capacitance (electrosorption), as the surface (outer) and intercalative (inner) charges stored by the Ni0.5Co0.5S electrodes are close to 46.0% and 54.0%, respectively. Additionally, a Ni0.5Co0.5S//AC two electrode full cell operating in asymmetric supercapacitor cell (ASCs) mode in 4 M KOH electrolyte exhibits an impressive energy density equivalent to 257 W h kg−1 and a power density of 0.73 kW kg−1 at a current rate of 1 A g−1. [ABSTRACT FROM AUTHOR]

Acetogenic bacteria produce CO2‐based chemicals in aqueous media by hydrogenotrophic conversion of CO2, but CO is the preferred carbon and electron source. Consequently, coupling CO2 electrolysis with bacterial fermentation within an integrated bio‐electrocatalytical system (BES) is promising, if CO2 reduction catalysts are available for the generation of CO in the complex biotic electrolyte. A standard stirred‐tank bioreactor was coupled to a zero‐gap PEM electrolysis cell for CO2 conversion, allowing voltage control and separation of the anode in one single cell. The cathodic CO2 reduction and the competing hydrogen evolution enabled in‐situ feeding of C. ragsdalei with CO and H2. Proof‐of‐concept was demonstrated in first batch processes with continuous CO2 gassing, as autotrophic growth and acetate formation was observed in the stirred BES in a voltage range of −2.4 to −3.0 V. The setup is suitable also for other bioelectrocatalytic reactions. Increased currents and lower overvoltages are however required. Atomically‐dispersed M−N−C catalysts show promise, if degradation throughout autoclaving can be omitted. The development of selective and autoclavable catalysts resistant to contamination and electrode design for the complex electrolyte will enable efficient bioelectrocatalytic power‐to‐X systems based on the introduced BES. [ABSTRACT FROM AUTHOR]

Abstract: In-plane permeability of gas diffusion backing (GDB) of proton exchange membrane fuel cells (PEMFCs) was investigated experimentally. Toray-paper and SGL-paper were selected as GDB test samples. Several Toray-papers were treated in-house with polytetrafluoroethylene (PTFE) using the immersion technique, dried either under atmospheric or vacuum pressure, and then sintered. The dependence of PTFE distribution in the through-plane direction on the PTFE drying conditions was examined using scanning electron microscopy (SEM)-based energy dispersive X-ray spectroscopy (EDS) imaging. The EDS image maps revealed that the PTFE distribution strongly depended on the drying condition, and PTFE drying under vacuum pressure yielded a relatively uniform PTFE distribution. The measured in-plane permeability suggests that the homogeneous distribution of PTFE achieved by the vacuum drying produces a porosity-leveling effect. In addition, the relationship between the in-plane permeability and porosity of the Toray-paper samples followed the Kozeny–Carman relation, whereas due to non-fibrous solids such as binder, that of the SGL-paper samples did not. [Copyright &y& Elsevier]

Abstract: We present an efficient, easy to construct, air-breathing biocathode for dioxygen reduction using the enzyme bilirubin oxidase encapsulated in a silicate gel film on Toray paper. Functionalised single-walled carbon nanotubes were used for improving electron transfer between the enzyme and the Toray paper. A current density of 1.2 mA cm−2 was measured under air without any mediators. The biocathode was connected with a Nafion-covered Zn-anode to form a zinc–oxygen battery. The biobattery has an open circuit voltage of 1.75 V and gives a maximum power density of 5.25 mW cm−2 at ca 0.4 V, which is the best result published so far for such a device. The device was used to power a two-LED bicycle lamp. [Copyright &y& Elsevier]

Abstract: This work investigates the degradation of an individual gas diffusion layer (GDL) by repeated freezing cycles. The pore size distribution, gas permeability, surface structure, and contact angle on the surface of the GDL were measured in four different types of GDL: SGL paper with a microporous layer (MPL); SGL paper with 5wt% of polytetrafluoroethylene (PTFE) loading; Toray paper without PTFE loading; and Toray paper with 20wt% of PTFE loading. After repeated freezing cycles, the porosity of the GDL without PTFE was reduced by 27.2% due to the volumetric expansion of the GDL. The peak of the log differential intrusion moved toward a smaller pore diameter slightly because of the repeated freezing process. The crack of the MPL increased in its width and length after repeated freezing cycles. The through-plane gas permeability of the GDL with the MPL doubled after repeated freezing cycles due to the growth of the crack in the MPL, but was very small for the GDLs with Toray paper. Besides, the GDLs with PTFE loading showed a relatively larger decrease in the contact angle on the surface than the GDL without PTFE loading due to the separation of PTFE from the carbon fiber during the repeated freezing process. [Copyright &y& Elsevier]

The increasing concentration of CO2 in the atmosphere and its impact on the climate are matters of significant concern. Extensive research is being conducted on molecular catalysts to electrochemically reduce CO2 into valuable products to disrupt the unidirectional carbon flow. This study compares two manganese bipyridine catalysts, tailored with four or two benzylic diethylamine groups in the secondary coordination sphere. Either of these amine‐bearing scaffolds positioned close to the Mn center serves as effective proton relays to facilitate the formation of the corresponding Mn hydride intermediate. Alongside competitive H2 evolution, the reaction of this crucial intermediate with CO2 leads to formate. Our findings underscore the pronounced influence of external Brønsted acids on product selectivity. Notably, when employing the catalyst bearing four amine groups, the HCOO−/H2 ratio varies from 81 : 3 with 1.0 M iPrOH to 16 : 64 with 1.0 M PhOH, while the Mn complex adorned with two amine pendant groups consistently favors HCOO−, irrespective of the utilized proton sources. Infrared spectroelectrochemistry and density‐functional theory calculations unveil distinct disparities in the reactivity of the Mn hydrides toward CO2 due to the change of ligand bulkiness in the two cases. This work substantiates the importance of modulating spatial accessibility while modifying the second sphere encompassing molecular catalysts. [ABSTRACT FROM AUTHOR]

The simultaneous upcycling of all components in lignocellulosic biomass and the greenhouse gas CO2 presents an attractive opportunity to synthesise sustainable and valuable chemicals. However, this approach is challenging to realise due to the difficulty of implementing a solution process to convert a robust and complex solid (lignocellulose) together with a barely soluble and stable gas (CO2). Herein, we present the complete oxidative valorisation of lignocellulose coupled to the reduction of low concentration CO2 through a three-stage fractionation–photocatalysis–electrolysis process. Lignocellulose from white birch wood was first pre-treated using an acidic solution to generate predominantly cellulosic- and lignin-based fractions. The solid cellulosic-based fraction was solubilised using cellulase (a cellulose depolymerising enzyme), followed by photocatalytic oxidation to formate with concomitant reduction of CO2 to syngas (a gas mixture of CO and H2) using a phosphonate-containing cobalt(II) bis(terpyridine) catalyst immobilised onto TiO2 nanoparticles. Photocatalysis generated 27.9 ± 2.0 μmolCO gTiO2−1 (TONCO = 2.8 ± 0.2; 16% CO selectivity) and 147.7 ± 12.0 μmolformate gTiO2−1 after 24 h solar light irradiation under 20 vol% CO2 in N2. The soluble lignin-based fraction was oxidised in an electrolyser to the value-added chemicals vanillin (0.62 g kglignin−1) and syringaldehyde (1.65 g kglignin−1) at the anode, while diluted CO2 (20 vol%) was converted to CO (20.5 ± 0.2 μmolCO cm−2 in 4 h) at a Co(II) porphyrin catalyst modified cathode (TONCO = 707 ± 7; 78% CO selectivity) at an applied voltage of −3 V. We thus demonstrate the complete valorisation of solid and a gaseous waste stream in a liquid phase process by combining fractioning, photo- and electrocatalysis using molecular hybrid nanomaterials assembled from earth abundant elements. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of carbon dioxide to formic acid is a promising pathway to improve CO2 utilization and has potential applications as a hydrogen storage medium. In this work, a zero-gap membrane electrode assembly architecture is developed for the direct electrochemical synthesis of formic acid from carbon dioxide. The key technological advancement is a perforated cation exchange membrane, which, when utilized in a forward bias bipolar membrane configuration, allows formic acid generated at the membrane interface to exit through the anode flow field at concentrations up to 0.25 M. Having no additional interlayer components between the anode and cathode this concept is positioned to leverage currently available materials and stack designs ubiquitous in fuel cell and H2 electrolysis, enabling a more rapid transition to scale and commercialization. The perforated cation exchange membrane configuration can achieve >75% Faradaic efficiency to formic acid at <2 V and 300 mA/cm2 in a 25 cm2 cell. More critically, a 55-hour stability test at 200 mA/cm2 shows stable Faradaic efficiency and cell voltage. Technoeconomic analysis is utilized to illustrate a path towards achieving cost parity with current formic acid production methods. Electrochemical reduction of CO2 to formic acid is a promising and sustainable pathway for valuable chemical generation. However, direct production of formic acid rather than formate is challenging. Herein the authors report a zero-gap membrane electrode assembly architecture with perforated cation exchange membrane for the direct electrochemical synthesis of formic acid from CO2. [ABSTRACT FROM AUTHOR]

The electroreduction of CO2 has been abundantly studied, but little attention has been given to the reaction occurring at the anode of this electrolyzer. Herein, we report one of the rare attempts to investigate the anode and potential reactions that could occur on this electrode during CO2 electrolysis. The electrooxidation of several aqueous pollutants, sulfamethazine (SMT), carbamazepine (CMP), ketamine and acetaminophen (ACE) was investigated at the anode of a CO2 electrolysis cell. Pulsed laser ablation in liquid (PLAL) was used to prepare the catalysts. PLAL is a versatile, environmentally safe technique used to create nanoparticles for electrocatalysis. Herein, bismuth nanoparticles were prepared as the CO2 reduction catalyst, as previously reported. Nickel nanoparticles were used for both the oxygen evolution reaction (OER) and the oxidation of the aqueous pollutants. Transmission electron microscopy (TEM) of the nickel nanoparticles indicates the production of monodisperse nanoparticles, with a 7.8 ± 2.8 nm average diameter. After evaluating the stability of the targeted pollutants, we focused on sulfamethazine, carbamazepine and acetaminophen due to their stability in aqueous environment. Among the various anode catalysts tested, nickel nanoparticles were the most versatile in degrading these pollutants; thus, further measurements were taken with this catalyst. A brief optimization of the degradation conditions (pH and potential) was also done, showing most efficient degradation at pH = 9 and 1.4 V vs Ag/AgCl. Once completed, CO2 reduction was coupled with the oxidation of a matrix of all three pollutants. The results show that the efficiency of the CO2 reduction was mostly unaffected by the combined presence of the pollutants at the anode. Oxidation of the target pharmaceuticals was also comparable to previous tests, reaching 62% for CMP, 53% for SMT and 33% for ACE within 20 min. [ABSTRACT FROM AUTHOR]