Disk Electrode Research Articles

A case for hybrid BCIs: combining optical and electrical modalities improves accuracy.

Near-infrared spectroscopy (NIRS) is a promising research tool that found its way into the field of brain-computer interfacing (BCI). BCI is crucially dependent on maximized usability thus demanding lightweight, compact, and low-cost hardware. We designed, built, and validated a hybrid BCI system incorporating one optical and two electrical modalities ameliorating usability issues. The novel hardware consisted of a NIRS device integrated with an electroencephalography (EEG) system that used two different types of electrodes: Regular gelled gold disk electrodes and tri-polar concentric ring electrodes (TCRE). BCI experiments with 16 volunteers implemented a two-dimensional motor imagery paradigm in off- and online sessions. Various non-canonical signal processing methods were used to extract and classify useful features from EEG, tEEG (EEG through TCRE electrodes), and NIRS. Our analysis demonstrated evidence of improvement in classification accuracy when using the TCRE electrodes compared to disk electrodes and the NIRS system. Based on our synchronous hybrid recording system, we could show that the combination of NIRS-EEG-tEEG performed significantly better than either single modality only.

Catalytic Activity and Stability of Non-Platinum Group Metal Oxides for the Oxygen Evolution Reaction in Anion Exchange Membrane Electrolyzers

The activities and stabilities of non-platinum group metals (PGMs) in the forms of monometallic (Mn2O3, Fe2O3, Co3O4, NiO) and bimetallic (NiFe2O4, CoNiO2) oxides were assessed for the oxygen evolution reaction (OER) in alkaline media and compared with IrO2. Both half-cell, rotating disc electrode (RDE) apparatus and single-cell, membrane electrode assemblies (MEA) were used to study kinetic and device-level performance in parallel and to provide insights into the use of these materials in anion exchange membrane (AEM) electrolyzers. Normalization of RDE results by geometric and physical surface areas, double layer capacitance, and metal content probed differences in physically vs electrochemically accessible surface areas and ensured reported trends were independent of the normalization method. The results showed that: (i) Ni- and Co- containing materials met or exceeded IrO2 performance in both RDE and MEA testing, (ii) Co3O4 deactivated over time-on-stream (1.8 V for 13.5 h) due to oxide and, relatedly, particle growth, (iii) NiFe2O4 increased in activity over time-on-stream due to dissolution of Fe and an increased Ni/Fe ratio, and (iv) reduction of catalyst layer resistance is an avenue to further increase device-level performance. These results demonstrated the clear viability for non-PGMs to be used as anode catalysts in AEM devices.

The Role of Oxygen Reduction Reaction in Determining Pit Stability of FeCr Alloys

Pitting corrosion is one of the most dangerous forms of corrosion, leading to sudden catastrophic failures in engineering system. Once initiated, pit propagation rates are largely dependent on the magnitude of the supporting cathodic current available from the oxygen reduction reaction (ORR) occurring on the external passive film. Here the ORR kinetics on conventional and high Cr content FeCr alloys made by arc-melter were investigated by experimental and computational methods. DFT calculations suggested that the overpotentials for the ORR on FeCr oxides are in the order Cr2O3 > Fe3O4 > Fe2O3 > FeCr2O4, which was experimentally confirmed on the FeCr alloys by rotating disc electrode experiments in both O2 saturated 0.1 M NaOH and 3.5 wt% NaCl. Koutecký-Levich analysis demonstrated that ORR follows a 4-electron pathway on all surfaces investigated. Moreover, the investigation of the Pourbaix diagrams of FeCr revealed that at potentials where pitting corrosion initiates the main constituents of the passive films should be a mixture of Fe2O3 and Cr2O3, rather than FeCr2O4, which is proved to be a good ORR catalyst. The results support the postulation that one role Cr additions play in the prevention of pitting corrosion is to suppress the ORR reaction.

Double-Layer Inhibition of Peroxydisulfate Reduction at Mercury Ultramicroelectrodes. A Quantitative Analysis of the Frumkin Effect Including Molecular Transport and Long-Range Electron Transfer

The electrical double layer (EDL) can lead to unexpected voltammetric phenomena. A notable example is the Frumkin effect, observed for the reduction of peroxydisulfate (S2O82–). In the absence of excess supporting electrolyte, the rate of S2O82– reduction decreases as the cathodic overpotential is increased, contrary to expectations for faradaic electron-transfer processes. Here, we report a demonstration of the Frumkin effect for S2O82– reduction at Hg ultramicroelectrodes, revealing steady-state voltammetry behavior consistent with prior observations at rotating disk electrodes. A finite element model is used to simulate the effect of the EDL on S2O82– reduction in the presence and absence of excess supporting electrolyte (K2SO4). Semiquantitative agreement between experimental and simulated voltammograms is obtained, including capturing the decrease in current for S2O82– reduction with increasing overpotential. We show that S2O82– migration within the EDL, at electrode potentials negative of the potential of zero charge, is the primary process responsible for the observed decrease in current with increasing driving force. These combined experiments and finite element simulations represent the first quantitative description of the Frumkin effect with rigorous inclusion of the EDL, migrational and diffusional mass-transport, and long-range electron transfer kinetics.

Neonatal Seizure Detection Using a Wearable Multi-Sensor System.

Neonatal seizure is an important clinical symptom of brain dysfunction, which is more common in infancy than in childhood. At present, video electroencephalogram (VEEG) technology is widely used in clinical practice. However, video electroencephalogram technology has several disadvantages. For example, the wires connecting the medical instruments may interfere with the infant's movement and the gel patch electrode or disk electrode commonly used to monitor EEG may cause skin allergies or even tears. For the above reasons, we developed a wearable multi-sensor platform for newborns to collect physiological and movement signals. In this study, we designed a second-generation multi-sensor platform and developed an automatic detection algorithm for neonatal seizures based on ECG, respiration and acceleration. Data for 38 neonates were recorded at the Children's Hospital of Fudan University in Shanghai. The total recording time was approximately 300 h. Four of the patients had seizures during data collection. The total recording time for the four patients was approximately 34 h, with 30 seizure episodes recorded. These data were evaluated by the algorithm. To evaluate the effectiveness of combining ECG, respiration and movement, we compared the performance of three types of seizure detectors. The first detector included features from ECG, respiration and acceleration records; the second detector incorporated features based on respiratory movement from respiration and acceleration records; and the third detector used only ECG-based features from ECG records. Our study illustrated that, compared with the detector utilizing individual modal features, multi-modal feature detectors could achieve favorable overall performance, reduce false alarm rates and give higher F-measures.

Effect of AST Atmosphere on Pt/C Electrocatalyst Degradation

The targeted development of novel stress testing protocols as well as the production of highly active and stable catalysts require abandoning a trial-and-error approach and transitioning to identifying the principal degradation mechanisms of electrocatalysts for PEMFCs under various conditions. Methodological aspects of research related to both qualitative and quantitative assessment of the materials’ robustness against degradation and its mechanisms become the key issues. In this study, accelerated stress testing has been conducted in Ar and O2 to identify the influence of the atmosphere on the degradation and durability mechanisms of the Pt/C catalysts. Initial and final parameters after the AST have been studied in detail by transmission electron microscopy and voltammetry using the rotating disk electrode technique. The Ostwald ripening (redeposition) of platinum particles has been established to be the predominant degradation mechanism during the testing in an O2 atmosphere, this being the agglomeration of nanoparticles during the testing in Ar. An ultra-small size and a narrow size distribution of platinum nanoparticles, as well as their uniform spatial distribution over the surface of the carbon support, have been shown to allow both ORR activity to be increased and durability to be enhanced.

Temperature dependent electrochemical reduction of CO2 at temperature controllable-rotating disk electrode modified with bismuth film

Temperature is an important parameter regulating the selectivity and reaction activity of electrochemical CO2 reduction reaction (CO2RR). However, it is challenging to evaluate the effect of temperature on electrochemical CO2RR without changing the CO2 solubility in water. Herein, a glassy carbon temperature controllable-rotating disk electrode (TCRDE-GC) was fabricated and the heat transfer was studied using temperature transfer coefficient (αT). As the only parameter required to calibrate the electrode surface temperature (Ts), αT was found to be correlated with the square root of the angular velocity of rotation. A bismuth film modified TCRDE was used to investigate Ts function on electrochemical CO2RR in the CO2-saturated K2SO4 solution where the CO2 solubility did not change. The apparent activation energy of electrochemical CO2RR was firstly reported as 46 kJ⋅mol−1. Electrochemical and ion chromatography results suggested that increasing Ts could accelerate the reaction rate of electrochemical CO2RR (increased by 170% with Ts increasing from 25 to 65 °C) and enhance product yield (increased by 40% with Ts increasing from 25 to 45 °C), whereas, could not change the type of main products. There was no regular effect of Ts on Faradic efficiency of HCOO− production. This work provides a new method to study the effect of electrode surface temperature on the CO2RR at the electrode / solution interface and it may be extended to other similar systems for further in-depth investigation.

Valorization of Naturally Abundant Low-Value Peat into Highly Active Non-Platinum Group Metal Oxygen Reduction Catalysts

This work explores the feasibility of synthesizing active non-platinum group metal oxygen reduction catalysts from naturally abundant peat through a facile one-pot method. The procedure yielded highly porous materials (specific surface area ~1000 m2 g-1) with promising oxygen reduction activity. Onset and half-wave potential values of 0.93 and 0.83 V vs RHE, respectively, were attained in rotating disc electrode experiments for the most active catalyst synthesized using dicyandiamide. Notably, the choice of nitrogen precursor influenced both the porosity and the electrochemical activity. Finally, the best-performing catalyst was analyzed in a rotating ring disc electrode setup, where the results confirmed those obtained in rotating disc electrode measurements.

Waste Tire Derived Carbon Support for Non-Platinum-Group Metal Catalyst Materials for Oxygen Reduction Reaction in Alkaline Medium

A porous carbon material was synthesized using waste tire granules via pyrolysis. Six non-platinum-group metal catalyst materials were synthesized based on this carbon material, Fe(NO3)3 · 9H2O, and either dicyandiamide or guanidine carbonate as the nitrogen source. Synthesis parameters such as pyrolysis temperature, precursor mass ratios, and acid washing time were varied for each material. All catalysts were characterized physically using HR-SEM, SEM-EDX, and N2 sorption analyses as well as electrochemically using the rotating disk electrode method in 0.1 M KOH. The materials were rich in nanofibers, and exhibited moderate porosity and specific surface area (S BET = 77-194 m2 g-1). By modifying the synthesis parameters of the materials, the electrochemical properties were successfully improved, achieving E onset = 0.92 V vs RHE and E 1/2 = 0.82 V vs RHE (Fe-guan III 900). The number of transferred electrons in the ORR was n = 4 for the more active materials.

Cu(InGa)(SeS)2 Electrodeposition from a Single Bath Using Pulsing Current Technique

Cu(In,Ga)(S,Se)2 (CIGSS) due to its greater band gap, has potential advantages over CuInGaSe2 (CIGS) as a photovoltaic film. Due to its lower capital cost and relatively high productivity, electrodeposition is a particularly appealing method for producing such solar materials (1-5). However, none describes the full production of such a molecule without the necessity for extra sulfur addition from the vapor phase4. Several recent articles disclose CIGSS electrodeposition. We introduce here the pulsing current method to dilute electrolytes used in previous work (6-7). Because of the diluted electrolyte composition, CIGSS can be directly electrodeposited from a single bath with a pulsing technique. The bath composition is 0.45 mM CuCl2-H2O; 0.4 mM InCl3; 0.77 mM H2SeO3; 0.51 mM GaCl3; and 0.3 mM Na2S2O3. PHydrion is applied to buffer the electrolyte to pH=2, and 0.7 M LiCl is applied as a supporting electrolyte. The flow was quantitatively characterized by agitation electrodeposition, which was done at room temperature onto a revolving disk electrode. Mass transport's impacts on deposit composition and substrate adherence are examined in various electrode rotation speeds and are represented by sample polarization curves. There was no requirement for the inclusion of metals from the gas phase during the subsequent annealing stage, which was carried out in an argon atmosphere. Two separate samples of absorber were evaluated for final sulfur atomic ratios of 5% and 15%. Utilizing the Energy-dispersive X-ray spectroscopy method, the final composition was calculated (EDS). CIGSS crystallography was analyzed using the XRD method.

A Planar Disk Electrode Chip Based on MWCNT/CS/Pb2+ Ionophore IV Nanomaterial Membrane for Trace Level Pb2+ Detection.

Unlike conventional lead ion (Pb2+) detecting methods, electrochemical methods have the attractive advantages of rapid response, good portability and high sensitivity. In this paper, a planar disk electrode modified by multiwalled carbon nanotube (MWCNTs)/chitosan (CS)/lead (Pb2+) ionophore IV nanomaterial and its matched system are proposed. This system presented a good linear relationship between the concentration of Pb2+ ions and the peak current in differential pulse stripping voltammetry (DPSV), under optimized conditions of -0.8 V deposition potential, 5.5 pH value, 240 s deposition time, performed sensitive detection of Pb2+ within sensitivity of 1.811 μA · μg-1 and detection limit of 0.08 μg · L-1. Meanwhile, the results of the system in detecting lead ions in real seawater samples are highly similar to that of inductively coupled plasma emission spectrometer (ICP-MS), which proved a practicability for the system in detection of trace-level Pb2+.

Insight into the poisoning effects and mechanisms of CH3SH, CH3CH2SH, CH3SCH3, and CH3CH2SCH2CH3 on Pt/C catalysts in fuel cell HOR

Trace amounts of sulphion can threaten the performance and lifespan of proton exchange membrane fuel cells (PEMFCs). The fuel mainly originates from refinery hydrogen, in which methyl mercaptan (MeSH), ethyl mercaptan (EtSH), dimethyl sulfide (DMS) and ethyl sulfide (EMS) inevitably exist. Herein, their negative effects are investigated on PEMFC and rotating disk electrode (RDE) levels, and the poisoning mechanisms are revealed by structural characterizations and density functional theory (DFT) calculations. The result indicates that MeSH and EtSH are 1.6 times more threatening than H2S, therefore, it is essential to limit the content of MeSH and EtSH. Nevertheless, the poisoning effect of DMS and EMS is weak enough to be tolerated. Moreover, the findings that the occupation of top site on Pt (111) weakly affects the hydrogen oxidation reaction (HOR) would contribute to the design of new catalysts with stronger toxicity resistance. This work is significant for the durability improvement of PEMFCs.

Zinc porphyrin/g-C3N4 S-scheme photocatalyst for efficient H2O2 production

Constructing heterojunction photocatalyst is a promising strategy to achieve solar-to-chemical energy conversion. Especially, the S-scheme heterojunction has received a great deal of attention because of its superiority of the efficient photogenerated charge carriers’ separation and the strong photoredox capacity. Herein, an S-scheme heterojunction is designed and synthesized through grafting supramolecular Zinc porphyrin (Zn-TCPP) on g-C3N4 (CN) via –CONH- bridging bond for H2O2 production in the O2 atmosphere under a 300 W Xe lamp irradiation using ethanol as a sacrificial agent. As the optimal sample, Zn-TCPP/CN exhibits the highest H2O2 production rate with 532.7 μmol/L within 90 min, which is 3.1 and 9.0 times higher than those of pure CN and Zn-TCPP, respectively. The route of H2O2 production in the photocatalytic process and the mechanism of activity enhancement are revealed by a systematic characterisation. Hence, the results of the radical trapping experiment and rotating disk electrode measurement demonstrate that the two-step single-electron route is the predominant reaction step in the process of H2O2 generation. In-situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) and Kelvin probe force microscopy (KPFM) technology provide strong evidence of the S-scheme charge transfer path between Zn-TCPP and CN, which greatly facilitates the spatial charge separation. Meanwhile, the density functional theory (DFT) calculations reveal that the strong interface interaction between Zn-TCPP and CN can induce the electron delocalization effect, thus restraining charge recombination. This work inspired the design of a high-active metalloporphyrin-based S-scheme heterojunction for energy conversion.

Super Hygroscopic Non‐Stoichiometric Cerium Oxide Particles as Electrode Component for PEM Fuel Cells

AbstractThe design of highly efficient promoters for the oxygen reduction reaction (ORR) is an important challenge in the large‐scale distribution of proton exchange membrane (PEM) fuel cells. Hygroscopic cerium oxide (CeO2) is here proposed as co‐catalyst in combination with Pt. Physical chemical characterizations, by means of X‐ray diffraction, vibrational spectroscopy, morphological and thermal analyses, were carried out, demonstrating high water affinity of the synthesized CeO2 nanoparticles. Composite catalysts (i. e., Pt : CeO2 1 : 0.5 and 1 : 1 wt:wt), were studied by either rotating disk electrode (RDE) and fuel cell tests performed at 80 °C and 110 °C. Interestingly, the cell adopting the Pt : CeO2 1 : 0.5 catalyst enabled the achievement of high power densities reaching ∼80 and ∼35 mW cm−2 under low relative humidity and high temperatures. This result demonstrates that tuning material surface properties (e. g. oxygen vacancies) could significantly boost the electrochemical performance of cathodes as a combined result of optimized water retention and improved ORR kinetic.

Space Confinement to Regulate Ultrafine CoPt Nanoalloy for Reliable Oxygen Reduction Reaction Catalyst in PEMFC.

A Co-based zeolitic imidazolate framework (ZIF-67) derived catalyst with ultrafine CoPt nanoalloy particles is designed via a two-step space confinement method, to achieve a robust oxygen reduction reaction (ORR) performance for proton exchange membrane fuel cell (PEMFC). The core-shell structure of ZIF-67 (core) and SiO2 (shell) is carefully adjusted to inhibit the agglomeration of Co nanoparticles. In the subsequent adsorption-annealing process, the in situ formed graphene shell on the surface of Co nanoparticles further protects metal particles from coalescence, leading to the ultrafine CoPt nanoalloy (average diameter is 2.61nm). Benefitting from the high utilization of Pt metal, the mass activity of CoPt nanoalloy catalyst reaches 681.8mA mgPt -1 at 0.9V versus RHE according to the rotating disk electrode test in 0.1m HClO4 solution. The CoPt nanoalloy-based PEMFC provides a high maximum power density of 2.22W cm-2 (H2 /O2 ) and 0.923W cm-2 (H2 /air). Simultaneously, itshows good stability in the long-time dynamic test at low humidity, due to the robust CoPt@graphene core-shell nanostructure. This work provides a viable strategy for designing Pt-based nanoalloy catalysts with ultrafine metal particles and high stability.

Spinel LiMn2O4 as Electrocatalyst toward Solid-State Zinc–Air Batteries

Efficient oxygen reduction reaction (ORR) electrocatalysts are the key to advancement of solid-state alkaline zinc–air batteries (ZAB). We demonstrate an electrocatalyst, spinel lithium-manganese oxide LiMn2O4 (LMO) by a simple hydrothermal method. Scanning electron microscope (SEM), X-ray diffraction (XRD), and Raman spectra indicate that the as-synthesized LiMn2O4 presents nanoscale irregular-shaped particles with the well-known spinel structure. The polarization curve, chronoamperometery curve, and linear scanning voltammograms of rotating disk electrode (RDE) results reveal that the as-synthesized LiMn2O4 possesses a higher electrocatalytic activity than that of electrolytic manganese dioxide for the ORR. A solid-state zinc–air cell with LiMn2O4 as the air electrode catalyst has a long voltage plateau of discharge and a discharge capacity of 188.4 mAh at a constant discharge current density of 10 mA·cm−2. In summary, spinel LiMn2O4 in which the JT effect enables electron hoping between Mn3+ and Mn4+ can be regarded as an effective robust oxygen reduction catalyst.

Transition-Metal and Nitrogen-Doped Carbon Nanotube/Graphene Composites as Cathode Catalysts for Anion-Exchange Membrane Fuel Cells

Transition-metal and nitrogen-doped graphene-like material and carbon nanotube (M-N-Gra/CNT) composites are prepared, characterized, and used as cathode catalysts in anion-exchange membrane fuel cells (AEMFCs). Melamine as a nitrogen source and cheap iron and cobalt salts as metal precursors are used for doping via high-temperature pyrolysis. The success of doping is proven by several physicochemical analysis methods, and the catalyst materials possess rather similar textural properties. The initial assessment of the oxygen reduction reaction activity using the rotating disk electrode method shows that Fe-N-Gra/CNT, Co-N-Gra/CNT, and CoFe-N-Gra/CNT materials have very similar electrocatalytic performances in alkaline media as well as excellent short-term stability but a different yield of HO2– formation. The M-N-Gra/CNT materials as cathode catalysts together with the Aemion+ reinforced anion-exchange membrane exhibit very good AEMFC performance, especially CoFe-N-Gra/CNT, comparable to that of Pt/C, reaching a peak power density of 638 mW cm–2. Such an excellent fuel cell performance of the M-N-Gra/CNT catalyst materials is attributed to the presence of M–Nx sites, carbon-encapsulated transition-metal nanoparticles, and feasible nitrogen-containing moieties.

Mechanistic Study of Fast Performance Decay of PtCu Alloy-based Catalyst Layers for Polymer Electrolyte Fuel Cells through Electrochemical Impedance Spectroscopy.

In the past, platinum-copper catalysts have proven to be highly active for the oxygen reduction reaction (ORR), but transferring the high activities measured in thin-film rotating disk electrodes (TF-RDEs) to high-performing membrane electrode assemblies (MEAs) has proven difficult due to stability issues during operation. High initial performance can be achieved. However, fast performance decay on a timescale of 24 h is induced by repeated voltage load steps with H2/air supplied. This performance decay is accelerated if high relative humidity (>60% RH) is set for a prolonged time and low voltages are applied during polarization. The reasons and possible solutions for this issue have been investigated by means of electrochemical impedance spectroscopy and distribution of relaxation time analysis (EIS-DRT). The affected electrochemical sub-processes have been identified by comparing the PtCu electrocatalyst with commercial Pt/C benchmark materials in homemade catalyst-coated membranes (CCMs). The proton transport resistance (Rpt) increased by a factor of ~2 compared to the benchmark materials. These results provide important insight into the challenges encountered with the de-alloyed PtCu/KB electrocatalyst during cell break-in and operation. This provides a basis for improvements in the catalysts' design and break-in procedures for the highly attractive PtCu/KB catalyst system.

Embedded Platinum–Cobalt Nanoalloys in Biomass-Derived Laser-Induced Graphene as Stable, Air-Breathing Cathodes for Zinc–Air Batteries

Fuel cells and metal–air batteries hold significant promise to help decarbonize transportation and the electricity grid. To encourage widespread adoption of these technologies, improvements to their air-breathing cathodes are required, which address problems such as the high cost of platinum (Pt) catalysts used to boost the kinetics of the oxygen reduction reaction (ORR) as well as the stability of Pt/C interfaces over long-term cycling. In this paper, we demonstrate a facile approach to reduce Pt content to less than 2 wt % by interfacing Pt with CoOx as well-dispersed nanoparticles entrapped within a highly conductive laser-induced graphene (LIG) matrix. Laser-induced carbonization of polymerized furfural alcohol preloaded with Co and Pt precursors resulted in the formation of a mixture of spherical nanoalloys PtCoOx and core (CoOx)–shell (Pt) structures. This LIG-PtCoOx electrode exhibited a low onset and half-wave potential in alkaline media, which closely approached a benchmark Pt/C. The effectiveness of LIG-PtCoOx was demonstrated by its performance in rotating disk and rotating ring disk electrode studies versus commercial Pt/C with the same concentration of the catalyst, which resulted in 4-fold greater mass activity and more than 6-fold higher specific activity, which are reflected in a high turnover frequency (TOF). The resulting material was tested as an air–cathode for zinc (Zn)–air batteries leading to improved stability (118 h of operation) and rechargeability (0.75 V voltage gap), exhibiting a higher peak power density compared to batteries assembled with the commercial benchmark Pt/C cathodes with similar composition.

Enhancement of the Hydrogen Oxidation Reaction in Alkaline Media via a Bi-functional Effect Using Tantalum as an Oxophilic Agent on NiMo/C

To avoid the increase of cost owing to the use of Pt group metal (PGM) catalysts, anion-exchange membrane fuel cells (AEMFCs) operating in an alkaline electrolyte environment where non-precious metals can be used are promising. However, the performance limitations of PGM-free catalysts still need to be overcome. In this study, Ta-on-NiMo/C fabricated by adding Ta on the surface of commercial NiMo/C via physical vapor deposition was developed as an anodic catalyst for AEMFCs with advanced performance. The high oxophilicity of Ta ensures a continuous OH– supply, and the bifunctional effect between Ta and Ni accelerates the hydrogen oxidation reaction (HOR). Therefore, Ta-on-NiMo/C exhibited 1.5 times more HOR activity than bare NiMo/C in rotating disk electrode experiments. Furthermore, the effect of Ta as the oxophilic agent was demonstrated by verifying the enhanced performance in a membrane electrode assembly in which Ta-on-NiMo/C was applied as an anodic catalyst.