Journal of The Electrochemical Society

The sensitive detection of down-regulator of transcription 1 (DR1) provides important information for early noninvasive diagnosis and treatment of Hashimoto thyroiditis (HT). In this study, a label-free electrochemical biosensor for DR1 detection was constructed based on electrodeposited gold nanoparticles (AuNPs) and poly(lactic-co-glycolic acid) (PLGA). The AuNPs were first modified to the electrode surface by electrodeposition to increase the specific surface area of the electrode, thus loading more target molecules to increase the sensitivity of the sensor. Then, a sandwich structure was formed on the electrode surface based on the specific recognition of antigen and antibody. PLGA was fixed on the electrode surface by binding with antibody 2 (Ab2) through amide bond to further improve the sensitivity of the sensor. Induced by the dual signal amplification, the sensor has a linear detection range of 50 fg·mL-1 to 50 ng·mL-1, with a detection limit as low as 19.4 fg·mL-1. Moreover, the sensor has good selectivity, specificity, and anti-interference capability, which holds great potential for the early diagnosis of HT and analysis of other disease markers.

Molecularly imprinted polymer (MIP) based electrochemical sensors have been generally exploited for the electrodes’ modification by virtue of their inherent specificity for the intrinsic template molecules. The purpose of the present research is to develop a MIP sensor via electrochemical polymerization for sensitive and selective determination of Nelarabine (NEL), a water-soluble prodrug of 9-β-d-arabinofuranosylguanine (ara-G). For the design of the MIP-based electrochemical sensor (MIP/PoPD/GCE), o-phenylenediamine (oPD) was chosen as the functional monomer. Electrochemical characterization of the MIP/PoPD/GCE sensor was carried out using electrochemical impedance spectroscopy and cyclic voltammetry, and surface characterization by scanning electron microscopy. Under the selected optimum experimental conditions, the dynamic linear reply range for NEL concentrations by the designed MIP sensor was between from 10.0 fM to 250.0 fM with limit of detection as 3.2 fM, demonstrating a good sensitivity as 1.0 × 10¹⁵ μA M⁻¹ for NEL detection based on measurements performed by differential pulse voltammetry. Electroanalytical implementations of the proposed MIP/PoPD/GCE sensor were studied employing pharmaceutical dosage forms and human serum samples.

A sewage sludge-derived biocarbon (SSB) was produced using biomass from a water treatment plant in Saltillo, Mexico. Its specific surface area was 412.0 m² g⁻¹, with an average pore diameter of 4.4 nm. Evaluation in an SSB||SSB symmetrical supercapacitor showed a high performance in several electrolytes (6 M KOH, 0.5 M Na2SO4, and 1 M NaClO4). The supercapacitor in KOH exhibited the highest specific capacitance (Csp) of 144.80 F g⁻¹ at 1 mV s⁻¹. Nevertheless, the widest operating voltage window of 2.5 V was attained in NaClO4. This enhanced behavior led to achieving energy density (ED) and power density (PD) values of 22.52 Wh kg⁻¹ and 508.0 W kg⁻¹, respectively, in the organic electrolyte. Moreover, rotating ring-disc electrode tests in 0.1 M KOH showed that SSB catalyzes the oxygen reduction reaction, with a low percentage of perhydroxyl ion produced ( %HO2− ) of 7.41% and a high electron transfer number (n) of 3.85 before an accelerated degradation test of 3000 cycles, sustaining a high stability after the cycling. This study provided evidence that high-performance active catalytic materials for symmetric supercapacitors and cathodes for anion exchange membrane fuel cells can be produced from Earth-abundant sewage sludge biomass.

In typical solid-contact potentiometric sensing, ion selective membranes (ISMs) play the role of recognizing the target analytes. A variety of solid-contact materials have been utilized to realize the ion-to-electron transduction. However, the ISMs show some drawbacks during practical application. Recent research efforts have been devoted to developing ISM-free potentiometric sensing. In this work, an ion-imprinted conducting poly (pyrrole-co-pyrrole-3-carboxylic acid) copolymer was investigated to achieve the ISM-free potentiometric sensing toward nitrate, an important anion to monitor in the environment. The copolymer-based electrochemical sensor afforded good potentiometric responses toward nitrate in a Nernstian manner, exhibiting superior or comparable sensing performances with existing ISM-based potentiometric sensors. Compared with polypyrrole homopolymer, the introduced carboxylate group in the side chain of the copolymer was likely to contribute to the redox activity, enabling better ion-to-electron transduction. More importantly, a unique self-doped effect was observed in the prepared poly (pyrrole-co-pyrrole-3-carboxylic acid), extending the working pH range of polypyrrole family and providing potential implications to develop electrochemical sensors when the environmental pH matters.

The maturation treatment, which involves exposing the composite electrode to high-humidity environment after casting slurry onto Al/Cu foil, has been reported to improve the charge-discharge performance of Si-based anodes that undergo significant volume changes during lithiation cycling. The precise mechanisms underlying this enhancement are not yet fully understood. Historically, two primary mechanisms have been proposed for the maturation process: (1) binder migration, which improves the uniformity and strength of the composite electrode, and (2) the dissolution of Cu²⁺ from the Cu current collector in the presence of an acidic binder, leading to cross-linking within the binder that reinforces the electrode. However, the dominance of these mechanisms remains unresolved. In this study, we investigated the contributions of these factors by applying maturation treatments to electrodes both with and without ball milling and employing polyacrylate-based binders of varying neutralization degrees. Maturation treatment significantly enhanced reversible capacity and capacity retention in electrodes without ball milling. Even in electrodes that underwent ball milling to obtain uniformity, a partial improvement was observed using polyacrylate binders of appropriate acidity, while non-acidic binders did not improve the cyclability. These results indicate that both mechanisms contribute significantly and that maturation treatment is beneficial even in well-dispersed electrodes.

A non-enzymatic sensor for uric acid detection based on an electro-transducer has been developed using screen-printed electrode-modified molecularly imprinted polymer (SPE-MIPs). The MIPs have been synthesized from uric acid (template), methacrylic acid/MAA (monomer), and ethylene glycol dimethacrylate/EGDMA (crosslinker) by photopolymerization procedure. The differential pulse voltammetry (DPV) method was used to test the uric acid sensor response. The linear response range of the uric acid electrochemical sensor was obtained from 0.595 to 356.905 µmolL-1 (R2=0.99) by DPV with a detection limit of 0.452 µmolL-1 at pH 7.0. In addition, the sensor has a sensitivity of -0.0188µA/µmolL-1. The uric acid extraction time is 30 min, while the uric acid re-extraction time is 14 min. The voltammetric uric acid sensor response showed good reproducibility with a promising relative standard deviation acquired at 5.643% (n=9). The ultra-high sensitivity performance of the developed uric acid sensor based on MAA and EGDMA molecularly imprinted polymer towards determining uric acid concentrations at low levels has demonstrated superior performance across previously reported electrochemical uric acid sensors based on various MIPs.

This study investigated the effects of two additives, sodium 1-naphthalenesulfonate (SNS) and sodium dodecyl sulfate (SDS), on electrodeposition of iron in acidic sulfate baths. Focusing on their influence on cathodic polarization and back-dissolution, as well as changes in the morphological characteristics and crystallographic orientation of iron deposits, the study utilized electrochemical assessments and morphological evaluations. Results indicate that SNS and SDS significantly reduce the nucleation overpotential (NOP) of iron, from 351 to 154 and 127 mV with optimal concentrations at 1 g l⁻¹ and 0.1 g l⁻¹, respectively. Both additives enhance the corrosion potential (Ec), thereby improving corrosion resistance. The additives can also reduce solution resistance (Rs) and charge transfer resistance (Rct), facilitating faster Fe²⁺ ion charge transfers and reducing dissolution of deposited iron. Moreover, SNS and SDS synergistically adjust the crystallographic plane orientation of Fe, promoting the formation of the (110) and (211) planes while suppressing the (200) planes, resulting in finer iron grains. Additionally, the TChkl index reaches a maximum value of 1.69. These findings underscore the crucial role of SNS and SDS in optimizing the iron electrodeposition process and enhancing the quality and stability of electrodeposited iron.

Theobromine (3,7-dimethylxanthine; TB) is a naturally occurring alkaloid found in various food products, such as chocolate, making cocoa and chocolate products its primary dietary sources. TB levels are higher in cocoa beans, approximately 1.2–5 g/100 g, in dark chocolates, approximately 1 g/100 g, and in milk chocolates, 0.1–0.5 g/100 g. This work describes a determination of theobromine with a screen-printed sensor with chemically-deposited boron-doped diamond electrodes (BDD SPEs). The proposed method has LOD of 0.5128 µM and a LOQ of 1.5539 µM, with BDD SPEs in 0.5 M H2SO4, for theobromine. Linear concentration range was obtained from 1 to 60 µM. Determination of TB was performed in the real sample analysis-chocolates with two different percentages of cocoa, using BDD SPEs, and results were confirmed with HPLC analysis. Furthermore, the modified BDD SPEs demonstrate remarkable characteristics, including exceptional stability, consistent repeatability, and optimal readiness for real-world applications.

Due to degradation or by design, the cathode electrode of a proton exchange membrane fuel cell (PEMFC) can exhibit an inhomogeneous Pt-distribution that can affect the assessment of electrode properties by electrochemical impedance spectroscopy (EIS), such as proton transport resistivity (Rp). In this study, bilayer cathodes of varying Pt loadings (Low-Low, Low-High, High-Low, and High-High) were fabricated to simulate homogeneous and heterogeneous Pt distributions. Hereby, the Low-High configuration mimics an aged electrode with a Pt-depleted region near the membrane and a Pt-rich area near the gas diffusion layer. Potentiostatic EIS (PEIS) spectra were compared at two bias potentials. At 0.2 V, where the PEIS measurement is strongly influenced by the pseudo-capacity of hydrogen underpotential deposition (Hupd) on the Pt surface, impedance spectra for nonhomogeneous bilayers deviated significantly from homogeneous bilayers. Conversely, at 0.45 V where the double-layer capacitance of the carbon support dominates, the EIS of homogeneous and inhomogeneous samples overlapped. Aging a commercial sample via load/unload accelerated stress tests resulted in a shift to higher values for Rp assessed at 0.2 V, while the spectra at 0.45 V remained constant, matching the Low-High bilayer sample. These findings highlight the importance of considering the Pt distribution when assessing electrode properties.

The cathode catalyst layer plays a crucial role in the performance of proton exchange membrane fuel cells (PEMFCs). It consists of a catalyst (platinum nanoparticles deposited on carbon nanoparticles) and an ionomer. The I/C ratio (ionomer mass / carbon mass) is a key parameter in optimizing catalyst layers. Here, catalyst layers containing a catalyst made of platinum nanoparticles deposited on high-surface-area carbon and Nafion D2020 as ionomer, with different I/C ratios, were structurally and electrochemically characterized. An I/C of 1.1 was found to be optimal in terms of performance and protonic resistance. Structural characterization of the ionomer in the catalyst layer was conducted using transmission electron microscopy, small-angle X-ray scattering, and small-angle neutron scattering. An innovative data processing method enabled small-angle X-ray scattering to provide the same information into the ionomer structure as small-angle neutron scattering. All characterizations showed that the ionomer was mostly well dispersed for all the tested I/C ratios. Increasing the I/C led to a more widespread ionomer network, which explains the observed improvement in performance and reduction in protonic resistance. However, scanning electron microscopy revealed that at an I/C of 1.3 or higher, porosity sharply decreased, partially explaining the reduced performance at higher I/C ratios.

We explored the in situ and real-time monitoring of the electric dipolar relaxation during the interaction of ammonia (NH3) gas, a crucial phenomenon in the gas sensing mechanism of conducting polymers, with dodecyl-benzene-sulfonic acid (DBSA)-doped polyaniline (PANI) nanocomposite polymer thin films. Dielectric spectroscopy from 20 Hz to 100 MHz was performed to analyze the dynamical behavior of the interaction process of DBSA-doped PANI nanocomposite polymer thin film with NH3 molecules. Initially, with no NH3 gas, the dielectric measurement showed a negative relative dielectric constant (about −6500 at 20 Hz) at low frequencies, indicating the conducting nature of unadorned DBSA-doped PANI nano-composite thin film (PANI-DBSA). On exposing PANI-DBSA film to NH3, the low frequency dipolar relaxation process was observed in the dielectric spectra. A shift toward the high frequency as a function of NH3 exposure time was observed, elucidating a continuous increase in dielectric strength and density of dipoles in the composite film with increasing exposure time which allows the gas a deeper penetration into the film and hence the increase in the density of dipoles. Removal of NH3 gas from PANI-DBSA allowed the system to retain its previous state,which is significant for sensing applications.

A two-step electropolymerization strategy was constructed to establish an electrochemical sensor method for sensitive and selective detection of betamethasone. First, a poly-(2-aminoterephthalic acid) (P(ATA)) layer, which can significantly enhance electronic conductivity, was synthesized on the surface of the bare electrode using electropolymerization. Subsequently, taurine (Tau), which is rich in sulphonate groups, was electropolymerized and introduced into the P(ATA) layer to obtain P(Tau)/P(ATA)/GCE. Then, the electropolymerization parameters and test conditions were optimized, including the concentration of polymerization solution, the scanning rate, the polymerization cycles, buffer pH and accumulation time. Characterization of the obtained electrodes done using scanning electron microscopy and several electrochemical characterization methods proved the successful preparation of the P(Tau)/P(ATA)/GCE. Electrochemical tests of betamethasone at different concentrations (0.2–25 μg·ml⁻¹) under optimal measurement conditions exhibited excellent linearity, good sensitivity. Compared with commonly employed HPLC method, the proposed sensor method was much fast, simple, environmentally friendly, and cost-effective. Compared with other sensor methods, P(Tau)/P(ATA)/GCE sensor exhibited good sensitivity and excellent stability. Moreover, the P(Tau)/P(ATA)/GCE sensor was successfully applied to quantitatively detect betamethasone in cosmetics, which provides a new method for the monitoring of illegal addition of glucocorticoids in cosmetics.

In this article, we show that adventitious water/electrolyte coming from various processing steps can obscure the assessment of results for a fully vapor-fed water electrolyzer. A couple hundreds of μl per cm² of water can sustain typical operating current densities of 10 mA cm⁻²geo for tens of hours, thereby not reflecting the true vapor-phase performance. This is a serious problem, especially for catalyst coated substrate architecture where surface non-uniformities behave as water pockets. We demonstrate that these water-pockets mediate the electrolysis process which can run for up to 30 h at 10 mA cm⁻²geo with or without the supply of humidity. Interestingly, the vapor-fed device stops functioning at a particular charge density that corresponds to the consumption of liquid water present in these pockets.

Lower anode catalyst loadings and higher current densities are essential to lowering the levelized cost of H2 production via proton exchange membrane water electrolysis (PEMWE). However, these approaches can induce significant durability challenges. Here, we show that cell degradation can include large reversible voltage losses across a variety of conditions, including low loadings and high currents. Although there is limited published discussion of reversible voltage losses in PEMWE, we demonstrate that they are an important consideration in cell efficiency and durability. Understanding the mechanisms of reversible losses and developing mitigation strategies is therefore a key priority for enabling low-cost PEMWE.

The function of supercapacitor electrodes was enhanced using Cadmium Oxide (CdO) nanorods synthesized at different calcination temperatures via a wet chemical technique and characterized. Structural analysis revealed changes in crystalline properties and size with varying calcination temperatures. The morphology of CdO nanorods, which exhibits uniform size, is suitable for application as supercapacitors. Temperature-dependent changes in crystalline characteristics were revealed by structural investigations. Galvanostatic charge-discharge (GCD) and cyclic voltammetry investigations support the pseudo-capacitive charge storage mechanism of CdO. A 169 F g⁻¹ specific capacitance was obtained for the CdO nanorods electrode material from the GCD profile, showing excellent capacitive retention of 84% for 100 cycles. This shows that pure CdO has high electrical conductivity, making it a better electrode material for supercapacitor application without doping. As scan rate increased, the specific capacitance dropped, suggesting less ion diffusion. Measured energy and power densities show promising results, with maximum values of 164 Wh kg⁻¹ and 25 kW kg⁻¹, respectively, at 1 A g⁻¹. Electrochemical impedance spectroscopy demonstrates low equivalent series resistance values (98 Ω after CV, 195 Ω after GCD), highlighting CdO nanorods’ suitability for supercapacitor applications. CdO nanorods show promising capacitive behavior, suggesting that they have the potential to be useful and affordable materials for energy storage.

Designing efficient and stable oxygen evolution reaction (OER) catalysts is crucial for advancing water electrolysis technologies toward sustainable hydrogen production. Ruthenium pyrochlore oxide (A2Ru2O7-δ) has attracted much attention due to its high OER catalytic activity and low cost. However, their catalytic activity and stability require further improvement to achieve commercial viability. In this study, a series of Pt-deposited Yttrium ruthenate (Y2Ru2O7-δ, YRO) bifunctional catalysts Pt(x%)-Y2Ru2O7 were prepared by hydrothermal and heat treatment methods. In an acidic environment, the OER activity and stability were significantly improved compared with YRO, and hydrogen evolution reaction (HER) performance gradually improved. Among them, Pt(25%)-YRO showed excellent OER (η10 = 260 mV, 43.1 mV dec-1) and HER (η10 =120 mV, 51.2 mV dec-1) performance. In addition, Pt(25%)-YRO demonstrated excellent catalytic stability, with both the OER and the overall water splitting reaction maintaining stable operation at 10 mA cm-2 for over 50 hours. This provides a new approach for developing high-activity, high-stability, dual-function water electrolytic catalysts for use in harsh acidic environments.

Gold nanoparticle-decorated reduced graphene oxides (AuNPs-rGOs) were used for the fabrication of a screen printer manufactured carbon electrode-based sensitive and portable immunosensor for the detection of scrub typhus. The AuNPs-rGOs were synthesized via a chemical reduction method and characterized via Fourier transform infrared spectroscopy, UV‒Vis spectroscopy, field emission scanning microscopy, and transmission electron microscopy. Furthermore, 56 kDa type-specific antigen (TSA) antibodies were used for immobilization over AuNPs-rGOs modified with SPCE via EDC-NHS (1:1) cross-linking chemistry. A type-specific antigen was used at different concentrations to observe the sensor response via cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy using potassium ferricyanide (K4[Fe(CN)6]3−/4−) as a redox indicator. The developed immunosensor showed excellent sensitivity of 47.80 μA cm⁻² ng⁻¹ and an LOD of 0.02 ng μl⁻¹. The developed immunohybrid immunosensor is portable because of its easy mobile connectivity and fast and low cost among scrub typhus biosensors. The sensor is highly specific for TSA detection and performs well in validation with ELISA-positive blood samples and TSA-spiked blood samples.

The electrodeposition of Cu2O, represented by the reaction 2Cu(II) + 2OH⁻ +2e → Cu2O + H2O in alkaline baths containing concentrated lactic acid (approximately 3 mol dm–3) as ligands, has been widely studied. In a previous study, such baths were found to generate the complexes [Cu(H–1L)L]– and [Cu(H–1L)2]2– (where L⁻ = CH3CH(OH)COO⁻ and H–1L⁻ = CH₃CH(O⁻)COO⁻) in a manner dependent on the bath pH in the alkaline region. This work first assessed the stability of these Cu(II)-lactate complexes based on computational chemistry. The formation of these complexes typically requires approximately one day to reach thermodynamic equilibrium, suggesting that other kinetically favorable, metastable complexes may form prior to the equilibrium complexes. Based on titration curves, [CuL2(HL)]0 was identified as the most likely such intermediate and the effect of this complex on deposition orientation was examined. Electrodeposited Cu2O obtained from a bath not yet at equilibrium with a pH of approximately 9.5 was randomly oriented whereas deposits from an equilibrated bath showed a preferential <100> orientation. These findings suggest that bath aging is an essential step in achieving reproducible Cu2O electrodeposition. Additionally, modifying the bath preparation method was found to prevent the formation of metastable complexes.

The overlapping redox potentials of analytes and the lack of selectivity present significant challenges for unmodified electrodes in electrochemical sensing. In this work, we have fabricated an electrochemical sensor based on cerium oxide nanocubes (CeO2-NCs) coated glassy carbon electrode (CeO2-NCs@GCE) for individual and simultaneous detection of dopamine (DA) and acetaminophen (APAP) with high sensitivity and selectivity. The CeO2-NCs were synthesized using a one-step hydrothermal method and characterized by transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and Raman spectroscopy. Cyclic voltammetry and electrochemical impedance spectroscopy were employed for electrochemical characterizations. With improved electrocatalytic redox activity due to enhanced active surface area and reduced interfacial charge transfer resistance, CeO2-NCs@GCE shows superior detection efficiency. The detection of DA and APAP was evaluated using differential pulse voltammetry. Low detection limit values of 0.696 µM for DA and 0.341 µM for APAP with a wide linear range of 10-400 µM applicability were achieved. The CeO2-NCs@GCE sensor was also used to detect DA in DA injection and APAP in paracetamol tablet samples. The developed sensor demonstrated satisfactory recovery results ranging from 96.5 to 102.8% in pharmaceutical samples, confirming the applicability of the proposed method for simultaneous detection of DA and APAP in real samples.

Electrochemical impedance spectroscopy (EIS) has been established as an effective technique for bacterial biofilm detection. Through the need for miniaturization, the application of novel electrode materials gains interest. In this study, we introduce Sputtered IRidium Oxide Film (SIROF) electrodes of varying sizes and geometries as sensors for biofilm detection. Pre-emptive cyclic voltammetry (pre-cycling) was used to transform as-sputtered anhydrous iridium oxide films into hydroxides, reducing the impedance and allowing the material to be adopted for miniaturized biofilm sensors. Our investigation showed that especially lower scan rates during this pre-cycling process reduced the interfacial impedance, hence optimizing electrode performance for this application. Using EIS in combination with pre-cycled SIROF electrodes, we detected biofilm growth within 24 hours and successfully distinguished between biofilms of S. aureus and P. aeruginosa. Additionally, we analyzed the influence of electrode size on biofilm detection and characterization. This study highlights SIROF electrodes as a promising platform for sensitive and scalable biofilm monitoring.

The large-scale commercialization of polymer electrolyte membrane fuel cells can significantly reduce greenhouse gas emissions from medium- and heavy-duty vehicle fleets. However, it is essential to enhance the long-term durability of the cathode catalyst layer (CCL), which degrades under operating conditions. Scanning transmission electron microscopy coupled with energy dispersive spectroscopy was used to investigate microstructural changes in four membrane electrode assemblies subjected to voltage cycling under different combination of stressors, including relative humidity (RH), upper and lower potential limits (UPL and LPL, respectively), dwell time, potential step, and cell temperature. The fluorine-to-platinum ratio was introduced to quantify the spatial distribution of platinum relative to the ionomer, both through-plane and in-plane. This metric, combined with nanoparticle size analysis, was used to assess initial heterogeneities and evaluate platinum losses. The main degradation modes were linked primarily to RH, dwell time, and potential step between UPL and LPL. High RH and a narrow potential step aided in the formation of a Pt depletion region near the membrane, excessive Pt band, and resulted in >50 nm agglomerates within the CCL. Moreover, longer dwell times resulted in enhanced NP growth from electrochemical Ostwald ripening.

A chiral drug must stereospecifically bind to the SARS-CoV-2 protein targets (Spike, RdRP, or 3CL protease) to form a stable diastereomeric complex for effective action. Herein, we show the enantioselective binding differences between anti-covid drug atorvastatin (RR-AT and SS-AT) isomers and bovine serum albumin (BSA). RR-AT (strong) and SS-AT (weak) form a 1:1 complex with BSA. Our findings, particularly the strong binding of RR-AT to BSA, hold significant promise for treating COVID-19. Using nitrogen-doped carbon nanofibers (NCNF) and polyvinyl chloride (PVC) with BSA, the device we developed is a step towards more effective and targeted treatments. The enantioselective solid contact ion selective electrode displays a Nernstian slope of 59.70 ± 0.20 mV/decade with a linear concentration range extending from 1.0 × 10–2 to 1.0 × 10–7 M, and a detection limit of 6.5 ± 0.16 × 10–8 M for the analysis of the RR-AT isomer. The sensor exhibited promising enantioselective detection of RR-AT in the presence of a large excess of SS-AT (1:99). Moreover, good recovery values, near 98-102 %, were achieved for the analysis of RR-AT in pharmaceutical and biological samples, including blood and urine samples from patients infected with SARS-CoV-2 on AT medication.

The degradation of the catalyst layer is the main reason for the performance reduction of the proton exchange membrane fuel cells. The effects of high potential holding time, cell temperature, and relative humidity (RH) on carbon corrosion of cathode catalyst layer are studied in the present paper. The fuel cell was maintained at 1.4 V under three conditions (80 °C and 100% RH, 60 °C and 100% RH, 80 °C and 40% RH) and at different durations. The carbon corrosion rate was faster under high temperature and high RH. After high-potential holding test, the membrane electrode assembly (MEA) showed a decrease in performance, electrochemical active surface area (ECSA), and proton conduction resistance within the catalyst layer, as well as an increase in charge transfer resistance. After maintaining 1.4 V for 180 min, the ECSA retention rate of MEAs are only about 30%. The changes in the ECSA and the proton conduction impedance precede the performance degradation, which could more quickly reflect the degradation of carbon materials. Furthermore, this work investigated the evolution process of carbon corrosion under high potential based on duration and proposed a three-stage degradation mechanism of the cathode catalyst layer.

A one-dimensional proton exchange membrane fuel cell (PEMFC) model was developed to consider the effect of mechanical stress on the transport parameters of each layer inside a cell. A genetic optimization algorithm was integrated to rapidly calibrate key parameters under various operating conditions. Sensitivity of the model parameters was systematically evaluated via Sobol global sensitivity analysis. The main conclusions are: the cell performance under different operating conditions can be obtained quickly and accurately by the developed model, and the maximum relative and absolute errors are controlled within 1.2% and 10 mV, respectively. The compression ratio of the membrane electrode assembly due to mechanical stress is a sensitive parameter. Determining the influence of mechanical stress can more accurately describe the transport phenomenon in the cell and improve the model’s prediction accuracy. By integrating genetic optimization algorithms, the optimal combination of model parameters can be efficiently determined. Moreover, the model exhibits certain blind calibration capability, maintaining absolute calibration errors within 25 mV and relative errors within 5%. This attribute suggests that the model can provide powerful support for design optimization of real cell systems, optimization of operation and management control strategies, and rapid assessment of the performance of mass-produced cell stacks.

Doxorubicin (DOX) is an anthracycline-derived medication used for its antitumor and antibiotic properties. Measuring DOX levels is important for treatment management, monitoring, and optimizing individual dosages. This work introduced a novel and sensitive electrochemical sensing platform for determination of DOX based on screen-printed carbon electrode (SPCE) modified with CoMoO4 nanosheets (NSs). A simple hydrothermal method was applied to prepare CoMoO4 NSs. Then, the characterization studies of prepared nanosheets were conducted by using field-emission scanning electron microscopy and X-ray diffraction analysis to provide necessary information about the morphological features and crystalline structure. The using of CoMoO4 NSs in the modification of SPCE facilitated the transfer rate of electrons, thereby improving the electrocatalytic performance of SPCE towards the redox process of DOX. This observation was obtained from the cyclic voltammetry studies. Also, on the basis of differential pulse voltammetry analysis for quantitative measurements, a linear calibration curve was obtained within a wide concentration range of DOX from 0.005 to 175.0 μM with a low detection limit of 0.0015 μM. Furthermore, the CoMoO4 NSs/SPCE sensor has been successfully employed in monitoring DOX in the DOX injection and urine sample, which can offer a suitable platform for qualitative analysis of drugs.