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In this study, a novel biodegradable polymer electrolyte membrane with reduced fuel crossover, high selectivity, and high conductivity compared with Nafion 117 membrane in direct ethanol fuel cells (DEFCs) has been reported. Herein, polyvinyl alcohol/epoxidized natural rubber (PVA/ENR) blend membranes were synthesized via a simple solution casting method and applied in DEFCs. The structural and physicochemical features of the PVA/ENR blend membranes were examined using FESEM, FTIR, XRD, water absorption, ethanol uptake, swelling ratio and oxidative stability. ENR enhances the chemical, structural, and mechanical characteristics of PVA, making it a valuable material in fuel cell applications. The incorporation of ENR into the PVA matrix results in a compact morphology, excessive multifunctional groups, low fuel crossover, and high selectivity. The optimum membrane thickness achieves the highest selectivity, reaching up to 12.32 × 104 S s cm−3 at 30°C. Additionally, the maximum power density achieved is 19.52 mW cm−2, surpassing that of the Nafion membrane, which is only 14.55 mW cm−2 at 90°C. Furthermore, this biodegradable membrane can sustain operation for 1000 h at 90°C, owing to its ability to maintain hydration for an extended period. This study represents the first attempt to combine PVA and ENR in fuel cells. [ABSTRACT FROM AUTHOR]

This study introduces a series of Rh–Pd bimetallic aerogels Rh 75 Pd 25 , Rh 50 Pd 50 , and Rh 25 Pd 75 as efficient electrocatalysts for ethanol electrooxidation, crucial for direct ethanol fuel cell technology. The bimetallic Rh–Pd and monometallic Rh and Pd aerogels were synthesized from RhCl 3 and PdCl 2 as starting materials and sodium borohydride as the reducing agent. A combination of X-ray photoelectron spectroscopy, elemental mapping, and electron microscopy studies of the bimetallic aerogels enable compositional analysis of the materials and provide insight into the porous 3D nanoarchitecture. Importantly, the material performs efficiently as an electrocatalyst on glassy carbon electrodes for the oxidation of ethanol under basic conditions (1.0 M KOH) at onset potentials ranging from −0.59 to −0.64 V (vs. Hg/HgO). Importantly, these materials exhibit high peak current densities of 216 mA/cm2 for the Rh-rich Rh 75 Pd 25 to 536 mA/cm2 for Rh 25 Pd 75 , which are significantly higher than reported peak current densities for other Pd-containing electrocatalysts. The 1H and 13C NMR techniques were used to evaluate products for ethanol electrooxidation, with the results indicating selectivity for acetic acid. This demonstrates an enhanced catalytic activity, selectivity to acetic acid vs. CO 2 , representing a significant step in advancing DEFCs and their broader application in sustainable energy technologies. [Display omitted] • Synthesis different Rh–Pd bimetallic aerogels Rh 75 Pd 25 , Rh 50 Pd 50 , and Rh 25 Pd 75. • Highly efficient electrocatalysts for ethanol electrooxidation. • Significant enhancements in catalytic activity to 536 mA/Cm2. • Bimetallic Rh–Pd aerogels selectively convert ethanol to acetic acid. [ABSTRACT FROM AUTHOR]

Efficient electrocatalysts are critical in the advancement of fuel cell technologies and should have superior activity for alcohol oxidation reactions (AORs). Herein, we report a facile one-pot method to synthesize platinum-bismuth nanoalloy (Pt–Bi) on reduced graphene oxide (RGO), enacting the methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) in an acidic solution. The reduction of the Pt and Bi precursors is co-mediated via l -ascorbic acid and ethylene glycol (EG) to afford Pt–Bi nanoparticles with an average size of 5.6 nm highly dispersed on the surface of RGO. Pt–Bi nanoparticle decoration is confirmed by transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX). X-ray photoelectron spectroscopy (XPS) results show the existence of the Pt–Bi metallic phase with minimal oxide. Electrochemical experiments using cyclic voltammetry (CV) reveal that the Pt–Bi/RGO catalyst is considerably more active than commercial Pt/C for AORs. Notably, the mass activity (J mass) of MOR is enhanced by 1.3-fold and EOR is enhanced by 2.3-fold, highlighting the influence of the Pt–Bi interfacial concept. Overall, the results suggest that Pt–Bi/RGO is a highly promising candidate for use in direct alcohol fuel cells. Schematic representation of the Pt–Bi/RGO electrocatalyst for methanol and ethanol direct oxidation reactions. [Display omitted] • Pt–Bi alloy on RGO synthesized successfully by a one-pot method. • Pt–Bi/RGO provides more active sites for methanol and ethanol electro-oxidation. • Bi enhances Pt–Bi nanoparticle CO tolerance for alcohol oxidation. • Pt–Bi/RGO shows mass activity of 0.458 and 0.384 mA μg⁻1-Pt for MOR and EOR. • Improved catalyst stability and activity due to Pt–Bi synergy on RGO support. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells (DEFCs) are better than others in commercially used FCs due to easy availability, less toxicity, and C‐2‐type alcohol. Ethanol has a high theoretical efficiency of 97% and is a safe, plentiful, and renewable resource that can be stored and controlled using the infrastructure that is in place now. Nevertheless, low functional efficiencies and the release of carbon dioxide (CO2), acetaldehyde, and byproducts of acetic acid must be addressed if DEFCs are to grow and become more commercially viable. To overcome these problems, new anode and cathode catalysts are needed, so this review article discusses the introduction of FCs with their structure, working and mechanism. Further, the report covers various types of FC catalysts, and their application in FC technology is explained. The role of the catalyst (such as anode and cathode), similarities and differences between Pt/Pd‐based catalysts, and the importance of supporting materials (such as carbon, transition metal dichalcogenides, MXene, and black phosphorus‐based materials) in DEFCs are described. In addition, the applications, advantages, and disadvantages of the DEFCs are discussed. Finally, the proposed theme is concluded with the existing challenges in this field and the future prospect of DEFCs. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cell can convert chemical energy into electric energy directly, and has the advantages of being free from Carnot cycle and being friendly to environment, so it has a broad application prospect. However, the insufficient activity and toxicity resistance of anodic catalysts limit their commercial application, mainly due to the limited adsorption sites and the toxic inactivation of catalysts resulting from the production of toxic intermediates (CO ads) during the ethanol oxidation reaction (EOR) process. In this study, the Au@PdAg porous hemispherical catalyst assembled by nanotubes was successfully prepared by soft template method and co-reduction method using dioctadecyl dimethyl ammonium chloride (DODAC) as surfactant, and its EOR performance was tested. Au@Pd 1.0 Ag 1.0 has the highest mass current density with a peak value of 4048.8 mA mg Pd − 1 , which is 7.8 times of Pd/C (JM). After 5000 s stability test, the residual current density value is still 863.4 mA mg Pd − 1 . The results showed that the introduction of the oxygenophilic metal Ag was conducive to the formation of OH ads and the oxidation of CO ads. The porous structure of the nanotube assembly facilitates electron transfer and provides more adsorption sites, which makes the catalyst show good electrocatalytic activity and anti-CO poisoning ability. [Display omitted] • Anisotropic hemispherical nanostructure was formed by BO 2 − inhomogeneous adsorption. • Porous hemispherical Au@PdAg catalyst enhancing ethanol electrooxidation was prepared. • The catalyst exhibited excellent activity and regenerative for ethanol oxidation. [ABSTRACT FROM AUTHOR]

In this study, the electro-oxidation reaction of ethanol over Pd–Cu supported on Cu porphyrin (TPPCu) was investigated. The catalyst was synthesized using the microwave-assisted polyol method and physicochemically characterized by XRD, XPS, SEM, EDS, TEM, EDAX, UV–Vis, FTIR, and RBS. A Cu-enriched catalyst with Cu3Pd, Pd,Cu, and TPPCu phases was identified using XRD and XPS. However, according to the RBS results, the catalytic surface was enriched with Pd, indicating that the interaction between TPPCu and Pd–Cu allowed the presence of Pd on the surface, thus enhancing the catalytic response of the material. This synthesis prevented the deprotonation of porphyrin on the electrocatalyst, as confirmed by XPS analysis. Electrochemical studies based on cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the response of the catalyst to variations in the scan rate and increasing ethanol concentration. The electrochemical response of PdCu/TPPCu improved with an increasing number of cycles, indicating improved mass transport, thus improving its electrochemical response and tolerance to CO contamination. This catalyst exhibited a high electroactive surface area of 49.4 m2/g, which could be related to the presence of TPPCu as a support. The behavior of the catalyst on the anode of a fuel cell fed with ethanol, bioethanol, and bioethanol residues was evaluated. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells (DEFCs) are better than others in commercially used FCs due to easy availability, less toxicity, and C‐2‐type alcohol. Ethanol has a high theoretical efficiency of 97% and is a safe, plentiful, and renewable resource that can be stored and controlled using the infrastructure that is in place now. Nevertheless, low functional efficiencies and the release of carbon dioxide (CO2), acetaldehyde, and byproducts of acetic acid must be addressed if DEFCs are to grow and become more commercially viable. To overcome these problems, new anode and cathode catalysts are needed, so this review article discusses the introduction of FCs with their structure, working and mechanism. Further, the report covers various types of FC catalysts, and their application in FC technology is explained. The role of the catalyst (such as anode and cathode), similarities and differences between Pt/Pd‐based catalysts, and the importance of supporting materials (such as carbon, transition metal dichalcogenides, MXene, and black phosphorus‐based materials) in DEFCs are described. In addition, the applications, advantages, and disadvantages of the DEFCs are discussed. Finally, the proposed theme is concluded with the existing challenges in this field and the future prospect of DEFCs.

Purpose: Effective performance of a direct ethanol fuel cell (FC) stack depends on the satisfactory operation of its individual cells where it is always challenging to manage the temperature gradient, water flow and distribution of reactants. In that, the design of the bipolar fuel flow path plate plays a vital role in achieving the aforementioned parameters. Further, the bipolar plates contribute 80% of the weight and 30%–40% of its total cost. Aim of this study is to enhance the efficiency of fuel to energy conversion and to minimize the overall cost of production. Design/methodology/approach: The authors have specifically designed, simulated and fabricated a standard 2.5 × 2.5 cm2 active area proton exchange membrane (PEM) FC flow path plate to study the performance by varying the flow fields in a single ladder, double ladder and interdigitated and varying channel geometries, namely, half curve, triangle and rectangle. Findings: Using the 3D PEMFC model and visualizing the physical and electrochemical processes occurring during the operation of the FCs resulted in a better-performing flow path plate design. It is fabricated by using additive manufacturing technology. In addition, the assembly of the full cell with the designed flow path plate shows about an 11.44% reduction in total weight, which has a significant bearing on its total cost as well as specific energy density in the stack cell. Originality/value: Simultaneous optimization of multiple flow path parameters being carried out for better performance is the hallmark of this study which resulted in enhanced energy density and reduced cost of device production. [ABSTRACT FROM AUTHOR]

Pt-based materials are commonly employed as catalysts in the electrooxidation of ethanol in direct ethanol fuel cells (DEFC). However, due to the complex nature of electrooxidation, the effect of catalyst properties on fuel cell power generation is not easily described by mechanistic models. Fuzzy systems can be used instead precisely for their ability to provide a more direct and qualitative/semiquantitative cause-effect relationship. In this study, a neurofuzzy model was developed to relate the effect of 5 input variables (4 catalyst properties, namely, crystal size, surface area, presence of PtSn phase and Pt L 3 -edge whiteline integrated intensity, and the cell potential) on cell current density. The fuzzy inference system (FIS) structure was constructed in MATLAB with ANFIS (Adaptive network-based FIS) based on experimental data used for training and validation. A 4-variable FIS (not including integrated intensity) was initially created and used as a basis for developing the 5-variable FIS, thus addressing the issue of fewer experimental data points available for integrated intensity. Both FIS structures exhibited very good fits to experimental data. The addition of integrated intensity as an input variable did not affect the fitted fuzzy model parameters for the other input variables and, therefore, a broader and more relevant model that included an electronic property of the catalyst was created. Response surface analyses, corroborated by particle swarm optimization, indicated that decreasing crystal size has the greatest effect in maximizing power density. Medium potentials and medium integrated intensity are also favorable. In addition, presence of the PtSn phase in moderate amounts is not unfavorable. With these values it was possible to predict the optimization of the power density value to 24.3 mW/cm2, compared to the best experimental value of 19.6 mW/cm2. • Neurofuzzy DEFC model to relate catalyst properties and potential to cell power. • FIS structures exhibited very good fits to experimental data. • Reducing crystal size has the greatest effect on maximizing power generation. • Medium potential and integrated intensity were favorable to higher power density. • PSO predicted optimal power density of 24.3 mW/cm2. [ABSTRACT FROM AUTHOR]

Cryogels from noble metal NPs have proven to be highly efficient catalysts due to their high specific surface area which increases the mass transfer channels and catalytic active sites. By using metal oxides as co-catalysts, the costs of the material can be significantly reduced, while the catalytic activity can remain the same or even improve due to synergetic effects. In this work, we synthesize different cryogel thin films supported on modified ITO substrates from Pt, Pd nanoparticles (NPs), and mixtures of these noble metals with γ-Fe2O3 NPs in a very low concentration (1 wt% of the noble metal). Structural and elemental analysis of the samples are performed, along with the measurement and analysis of their catalytic activity. The electrocatalytic activity of the cryogels towards ethanol oxidation reaction (EOR) in alkaline media was evaluated by means of cyclic voltammetry. By mixing γ-Fe2O3 NPs with Pt or Pd NPs in the cryogel structure, we observe increased tolerance against poisonous surface intermediates produced during the EOR. Moreover, we observe an increase in the catalytic activity towards EOR in the case of the 1 wt% Pd/γ-Fe2O3 cryogel, making them promising materials for the development of direct ethanol fuel cells. [ABSTRACT FROM AUTHOR]

In this work, it has been experimentally proven that the kinetic performance of a common Direct Catalytic Ethanol Fuel Cell (DCEFC) can be increased by introducing nanostructured (ZnII,AlIII(OH)2)+NO3−·H2O Layered Double Hydroxides (LDHs) into the anode compartment. Carrying out the measurements with the open-circuit voltage method and using a kinetic format, it has been shown that the introduction of LDHs in the anodic compartment implies a 1.3-fold increase in the calibration sensitivity of the method. This improvement becomes even greater in the presence of hydrogen peroxide in a solution. Furthermore, we show that the calibration sensitivity increased by 8-times, when the fuel cell is modified by the enzyme catalase, crosslinked on LDHs and in the presence of hydrogen peroxide. The fuel cell, thus modified (with or without enzyme), has been used for analytical applications on real samples, such as biological (human saliva) and hand disinfectant samples, commonly used for the prevention of COVID-19, obtaining very positive results from both analytical and kinetic points of view on ethanol detection. Moreover, if the increase in the calibration sensitivity is of great importance from the point of view of analytical applications, it must be remarked that the increase in the speed of the ethanol oxidation process in the fuel cell can also be extremely useful for the purposes of improving the energy performance of a DCEFC. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells have been widely investigated as nontoxic and low-corrosive energy conversion devices with high energy and power densities. It is still challenging to develop high-activity and durable catalysts for a complete ethanol oxidation reaction on the anode and accelerated oxygen reduction reaction on the cathode. The materials' physics and chemistry at the catalytic interface play a vital role in determining the overall performance of the catalysts. Herein, we propose a Pd/Co@N-C catalyst that can be used as a model system to study the synergism and engineering at the solid-solid interface. Particularly, the transformation of amorphous carbon to highly graphitic carbon promoted by cobalt nanoparticles helps achieve the spatial confinement effect, which prevents structural degradation of the catalysts. The strong catalyst-support and electronic effects at the interface between palladium and Co@N-C endow the electron-deficient state of palladium, which enhances the electron transfer and improved activity/durability. The Pd/Co@N-C delivers a maximum power density of 438 mW cm−2 in direct ethanol fuel cells and can be operated stably for more than 1000 hours. This work presents a strategy for the ingenious catalyst structural design that will promote the development of fuel cells and other sustainable energy-related technologies. It is challenging to develop high-activity and durable catalysts for both ethanol oxidation reaction on the anode and oxygen reduction reaction on the cathode. Here in this work, authors proposed Pd/Co@N-C catalyst as a model to synergistically maximize the usage of catalyst nanoparticles and active interfaces for direct ethanol fuel cells. [ABSTRACT FROM AUTHOR]

Owing to the advantages of large energy density, excellent conversion efficiency, and safety for storage, direct ethanol fuel cells (DEFCs) possess an extensive range of applications in alkaline mediums. In this study, we successfully synthesize the PdSn nanoparticles (NPs) with a different molar ratio of Pd/Sn by a simple one‐step method. The alloyed PdSn NPs present higher electrocatalytic activity and better stability than that of the commercial Pd/C toward ethanol oxidation reaction (EOR). Especially, the PdSn@NP‐2 displayed the best electrocatalytic performance among the as‐prepared samples, the current density for EOR in the alkaline condition of which can even approach 2463.8 mA mg−1, approximately 3.6 times of the commercial Pd/C (700 mA mg−1). Meanwhile, on the base of the electrochemical measurement, it is also observed that increasing temperature and concentrations of KOH/C2H5OH for PdSn NPs positively affect on the current density of the above samples. [ABSTRACT FROM AUTHOR]

The engineering of robust electrocatalysts for the ethanol oxidation reaction (EOR) with cost-natural, superior electrocatalytic activity, and stability, is crucial for the scaled-up applications of direct ethanol fuel cells. Herein, a facile bottom-up hydrothermal strategy has been implemented to synthesize N,P,S triple-doped 3-dimensional (3D) graphene architectures (N,P,S-3DG) with interconnected, hierarchical porous structure, followed by Pd nanoparticles were uniformly decorated onto the N,P,S-3DG via solvothermal approach. As fabricated hybrid nanocatalyst, labeled as Pd@N,P,S-3DG, is of charming physicochemical characteristics including large electrochemically active specific surface area, interconnected hierarchical pore network, a satisfactory percentage of heteroatom dopants, uniform distribution of Pd nanoparticles, as well as superior electrocatalytic performance metrics such as high catalytic activity, long-term stability, and tolerance to poisoning. The characterizations have confirmed the strong electrostatic interaction between the Pd nanoparticles and carbonaceous support material, thereby leading to homogeneously anchoring Pd nanoparticles onto 3D architecture and forming of novel active sites as well as synergistically boosting the EOR catalytic activity. The Pd@N,P,S-3DG has offered an enlarged electrochemically active surface area (50.3 m2 g−1), an enhanced catalytic current density of 1784 mA mg−1 Pd , and outstanding long-term stability, thereby distinctly transcending those of commercial carbonaceous material-supported Pd catalysts. The work is of great importance since it may pave the way for the rational design of low-cost high-performance carbonaceous-based nano-electrocatalysts to be utilized in large-scale energy applications. [Display omitted] • Bottom-up strategy was used to synthesize N,P,S triple-doped 3 dimensional graphene. • Pd nanoparticles were uniformly decorated onto N,P,S-3DG by solvothermal approach. • Pd@N,P,S-3D was utilized as electrocatalyst towards ethanol oxidation reaction. • Synergistic effect of heteroatoms boosted the electrocatalytic activity. • 3-dimensional network facilitated the ion transfer and reduced the resistance. [ABSTRACT FROM AUTHOR]

Paper-based microfluidic fuel cells (PMFCs) are attracting extensive attention for their low cost, simple structure and environmental friendliness, making them suitable for wearable devices and micro-detection instruments. However, the small electrode area limits their power output. To date, researchers try to tackle this issue by developing complex PMFC stacks, but the research on direct expansion of single-cell's electrode area is still missing. This study explores three strategies to expand PMFC's electrode, namely the vertical scaling-up, the horizontal scaling-up and the horizontal scaling-up with additional wires. Results show that the vertical scaling-up increases ionic resistance while the horizontal scaling-up increases electrical resistance significantly, leading to limited scaling-up efficiency of 20.9 % and 37.5 %, respectively, when the electrode area is expanded for 5 times. On the contrary, the horizontal scaling-up with additional wires can reduce the ionic and electric resistances concurrently, achieving a much higher scaling-up efficiency of 64.3 %. Furthermore, rolling up the scaled-up PMFC can reduce device footprint with negligible performance loss, showcasing its excellent flexibility and high potential for practical applications. [ABSTRACT FROM AUTHOR]

Alkaline direct ethanol fuel cells (DEFCs) represent an efficient energy conversion device for sustainable ethanol fuel. In this study, a design with new structural parameters for the anodic flow field of the alkaline DEFC was modeled with the aid of computational fluid dynamics and was then actually constructed. Single-cell tests were performed to evaluate the impact of the developed design on fuel cell performance. The results show that fuel cell performance significantly increased when using the improved design in the low-temperature range. The higher the temperature in the cell, the lower the influence of the flow field structure on performance. In addition, the influence of external factors, such as the orientation of the cell, the preheating of the fuel, and the direction of the two fuel flows relative to each other (co-current and counter-current), are shown. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells (DEFCs) are considered the most suitable direct alcohol fuel cell (DAFC) in terms of safety and current density. The obstacle to DEFC commercialization is the low reaction kinetics of ethanol (C2H5OH) oxidation because of the poor performance of the electrocatalyst. In this study, for the first time, graphene nanoplates (GNPs) were coated with sulfated zirconium dioxide (ZrO2) as adequate support for platinum (Pt) catalysts in DEFCs. A Pt/S-ZrO2-GNP electrocatalyst was prepared by a new process, polyol synthesis, using microwave heating. Field emission scanning electron microscope (FESEM) imaging revealed well-dispersed platinum nanoparticles supported on the S-ZrO2-GNP powder. Analysis of the Fourier transform infrared (FTIR) spectrometry confirmed that sulfate modified the surfaces of the sample. In X-ray diffraction (XRD), no effect of S-ZrO2 on the crystallinity net in Pt was found. Pt/S-ZrO2-GNP electrode outperformed those with unsulfated counterparts, primarily for the higher access with electron and proton, confirming sulfonating as a practical approach for increasing the performance, electrocatalytic activity, and carbon monoxide (CO) tolerance in an electrocatalyst. A considerable decrease in the voltage of the CO electrooxidation peak from 0.93 V for Pt/C to 0.76 V for the Pt/S-ZrO2-GNP electrode demonstrates that the new material increases activity for CO electrooxidation. Moreover, the as-prepared Pt/S-ZrO2-GNPs electrocatalyst exhibits high catalytic activity for the EOR in terms of electrochemical surface area with respect to Pt/ZrO2-GNPs and Pt/C (199.1 vs. 95 and 67.2 cm2.mg−1 Pt), which may be attributed to structural changes caused by the high specific surface area of graphene nanoplates catalyst support and sulfonating effect as mentioned above. Moreover, EIS results showed that the Pt/S-ZrO2-GNPs electrocatalyst has a lower charge transfer resistance than Pt/ ZrO2-GNPs and Pt/C in the presence of ethanol demonstrating an increased ethanol oxidation activity and reaction kinetics by Pt/S-ZrO2-GNPs. [ABSTRACT FROM AUTHOR]

Direct methanol and ethanol fuel cells are important components of the development and application of emerging contemporary energy carriers. However, most electrocatalysts used in the methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) have very limited durability. Herein, a strategy for Pd2+ loading on a specific covalent organic framework (COF) by impregnation is disclosed. Then, high-temperature carbonization is used to convert it into a COF-derived nitrogen-doped carbon (CN) to obtain a series of Pd–CN catalysts with different Pd loadings. Among them, Pd–CN-2 (with 2.51 wt%) exhibits high activity in the MOR and EOR. Its activity in the MOR is 2.93 A mgPd−1 (much more active than Pd/C-0.20 A mgPd−1). In the EOR, it reached 5.44 A mgPd−1, 25 times higher than that of Pd/C (0.22 A mgPd−1). In addition, the catalyst shows superior stability in both the MOR and EOR, maintaining more than 90% of its initial mass activity after a 40 000 s stability test. Its high activity and stability are probably attributed to the extraordinary stability of COF-derived CN materials and the interaction between Pd and CN. This work provides a general synthesis idea of obtaining highly efficient and stable metal–carbon–nitrogen electrocatalysts for application in fuel cells. [ABSTRACT FROM AUTHOR]

Although considerable effort has been devoted to developing bifunctional electrocatalysts with enhanced atomic utilization in ethanol fuel cells, significant progress in this field has been hindered by notable drawbacks of the electrocatalysts, such as low stability, poor activity, and inefficient repeatability for multiple startup and shutdown cycles. Considering these issues herein, a novel nanosized GaPtMnP alloy anchored on N‐doped multiwall carbon nanotubes (MWCNTs) is developed. The average size of the spherical GaPtMnP alloy nanoparticles is ≈3.5 nm. The atomic structure and d‐band shift of Pt in the GaPtMnP alloy are demonstrated using state‐of‐the‐art density functional theory calculations. Cyclic voltammetry analysis revealed that GaPtMnP/N‐MWCNT delivered high mass and specific activities of 9.16 A mgPt−1 and 10.4 mA cm−2, respectively, in 0.3 m H2SO4 + 0.5 m ethanol, values that are ≈13‐ and 8‐fold higher than the corresponding values for Pt/C. In addition, it exhibits long‐term stability and durability even after 3000 cycles. A single cell based on the GaPtMnP/N‐MWCNT anodic electrocatalyst exhibits a peak power density of 86.64 mW cm−2, which is approximately fourfold higher than that of Pt/C at 70 °C. Furthermore, the performance of a fuel cell comprising the GaPtMnP/N‐MWCNT catalyst remained constant even after multiple startup–shutdown cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rh-decorated Pd nanocubes demonstrate superior ethanol oxidation efficiency. • Ni(OH) 2 nanosheets support enhances the generation of oxygenated species. • The Rh/Pd/Ni(OH) 2 /C outperforms Pd/C in specific activity for ethanol oxidation. • The Rh/Pd/Ni(OH) 2 /C nanocatalysts exhibit promising DEFC potential. This study investigates the improvement of Palladium (Pd)-based nanocatalysts for ethanol oxidation in alkaline solutions, a process often hindered by the poisoning of the catalyst's surface. We synthesise Pd nanocubes and Rhodium (Rh)-decorated Pd nanocubes, both supported by a composite of nickel hydroxide nanosheets and carbon (Ni(OH) 2 /C). The developed Pd nanocatalysts possess a nanocubic morphology with smaller sizes compared to Pd/C, alongside additional nanostructures like nanorods X-ray absorption near-edge structure and extended X-ray absorption fine structure analyses suggest that Rh decoration on Pd nanocubes prevents Pd oxidation, with Rh itself being oxidised. The electrocatalytic performance of the Rh/Pd/Ni(OH) 2 /C hybrid catalyst displays a notable enhancement, attributed to the combined effects of the exposed Pd (1 0 0) crystal surfaces, the addition of oxygenated species through the Ni(OH) 2 component, and the deliberate addition of Rh. Comparative assessments reveal that this composite surpasses Pd/C and Pd/C nanocubes, achieving specific activities that are approximately 11.6 and 3.5 times greater, respectively. Electrochemical Impedance Spectroscopy data and chronoamperometric studies confirm superior ethanol oxidation efficiency and improved catalytic stability. These findings highlight the utility of Rh/Pd/Ni(OH) 2 /C nanocubes in direct ethanol fuel cells, providing promising pathways for enhancing fuel cell technologies. [ABSTRACT FROM AUTHOR]

Over the years, direct ethanol fuel cells have aroused wide concern in sustainable development. At the same time, researchers are committed to developing low-cost and high-efficiency fuel cells, especially catalysts as the core component. In this work, PdBi nanochains (NCs) were synthesized by a brief one-step method and applied as catalysts. Among these PdBi NCs catalysts, the Pd 79 Bi 21 NCs displayed the topmost mass activity of 1.74 A mg Pd −1 for ethanol oxidation reaction, which was three times that of commercial Pd/C. In addition, it performed well in terms of temporal stability. According to a series of characterization results, its excellent performance was attributed to several merits: (i) the electronic structure of Pd was modified after doping Bi, which could weaken the interaction between Pd and CO or other intermediates; (ii) defects (the grain boundaries, for instance) would provide abundant active sites in the catalytic reactions; (iii) the nanochain-based structure was conducive to the complete exposure of active reaction sites and the improvement of stability. • Ultrathin PdBi nanochains are synthesized by a brief one-step method. • The PdBi nanochains exhibit excellent catalytic performance in ethanol oxidation reaction. • The morphology of materials and the electronic structure of Pd are effectively adjusted by introducing Bi. [ABSTRACT FROM AUTHOR]

Tailoring effective electrocatalysts for the ethanol oxidation process with low-price, high electrocatalytic activity, and long lifetime is crucial for large-scale application of direct ethanol fuel cells. Herein, it was aimed to provide a facile method for designing Polyaniline-Manganese ferrite (PANI-MnFe2O4) supported nanocatalysts modified with Pt/Ru to be utilized for ethanol electrooxidation. The successful synthesis of the PANI-MnFe2O4/Pt/Ru nanocomposite was confirmed by the physicochemical analysis techniques including Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and X-ray diffraction. The electrooxidation of ethanol at room temperature was investigated using a number of electrochemical characterizations such as cyclic voltammetry, linear sweep voltammetry, and chronoamperometry techniques. In comparison to other electrodes, the PANI-MnFe2O4/Pt–Ru electrode demonstrated superior efficiency in terms of boosting forward current (If, 100 mAcm−2) and increasing the electrochemically active surface area (ECSA, 30.3) that was required for ethanol molecules during the oxidation process. Furthermore, results demonstrated that introducing Ru and Pt to the PANI-MnFe2O4 support enhanced its efficiency towards the ethanol oxidation reaction by boosting both the stability (94%) and the carbon monoxide tolerance, which are both critical for alkaline direct ethanol fuel cell practical applications. This study paves the way for a novel approach for engineering high-performance, low-cost electrocatalysts that may be utilized as an alternative to commercial electrocatalysts in fuel cell technology. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells are among the most efficient and environmentally friendly energy‐conversion devices and have been widely focused. The ethanol oxidation reaction (EOR) is a multielectron process with slow kinetics. The large amount of by‐product generated by incomplete oxidation greatly reduces the efficiency of energy conversion through the EOR. In this study, a novel type of trimetallene called porous PdWM (M = Nb, Mo and Ta) is synthesized by a facile method. The mass activity (15.6 A mgPd−1) and C1 selectivity (55.5%) of Pd50W27Nb23/C trimetallene, obtained after optimizing the compositions and proportions of porous PdWM, outperform those of commercial Pt/C (1.3 A mgPt−1, 5.9%), Pd/C (5.0 A mgPd−1, 7.2%), and Pd97W3/C bimetallene (9.5 A mgPd−1, 14.1%). The mechanism by which Pd50W27Nb23/C enhances the EOR performance is evaluated by in situ Fourier transform infrared spectroscopy and density functional theory calculations. It is found that W and Nb enhance the adsorption of CH3CH2OH and oxophilic high‐valence Nb accelerates the subsequent oxidation of CO and CHx species. Moreover, Nb promotes the cleavage of CC bonds and increases the C1 selectivity. Pd60W28Mo12/C and Pd64W27Ta9/C trimetallene synthesized by the same method also exhibit excellent EOR performance. [ABSTRACT FROM AUTHOR]

Rational design and synthesis of superior electrocatalysts for ethanol oxidation is crucial to practical applications of direct ethanol fuel cells. Here, we report that the construction of Pd-Zn dual sites with well exposure and uniformity can significantly improve the efficiency of ethanol electro-oxidation. Through synthetic method control, Pd-Zn dual sites on intermetallic PdZn nanoparticles, Pd-Pd sites on Pd nanoparticles and individual Pd sites are respectively obtained on the same N-doped carbon coated ZnO support. Compared with Pd-Pd sites and individual Pd sites, Pd-Zn dual sites display much higher activity for ethanol electro-oxidation, exceeding that of commercial Pd/C by a factor of ~24. Further computational studies disclose that Pd-Zn dual sites promote the adsorption of ethanol and hydroxide ion to optimize the electro-oxidation pathway with dramatically reduced energy barriers, leading to the superior activity. This work provides valuable clues for developing high-performance ethanol electro-oxidation catalysts for fuel cells. Rational design and synthesis of superior electrocatalysts for ethanol oxidation is crucial to practical applications of direct ethanol fuel cells. Here, authors report the construction of Pd-Zn dual sites with well exposure and uniformity can improve the efficiency of ethanol electro-oxidation. [ABSTRACT FROM AUTHOR]

Crosslinked anion exchange membranes (AEMs) made from poly(vinyl alcohol) (PVA) as a backbone polymer and different approaches to functional group introduction were prepared by means of solution casting with thermal and chemical crosslinking. Membrane characterization was performed by SEM, FTIR, and thermogravimetric analyses. The performance of AEMs was evaluated by water uptake, swelling degree, ion exchange capacity, OH-conductivity, and single cell tests. A combination of quaternized ammonium poly(vinyl alcohol) (QPVA) and poly(diallyldimethylammonium chloride) (PDDMAC) showed the highest conductivity, water uptake, and swelling among other functional group sources. The AEM with a combined mass ratio of QPVA and PDDMAC of 1:0.5 (QPV/PDD0.5) has the highest hydroxide conductivity of 54.46 mS cm-1. The single fuel cell tests with QPV/PDD0.5 membrane yield the maximum power density and current density of 8.6 mW cm-2 and 47.6 mA cm-2 at 57°C. This study demonstrates that PVA-based AEMs have the potential for alkaline direct ethanol fuel cells (ADEFCs) application. [ABSTRACT FROM AUTHOR]

Of late, fuel cells have drawn great attentions owing to high-energy demands, fossil fuel depletion and worldwide environmental pollution. Direct ethanol fuel cell (DEFC) constituted as one of the most promising sources of green energy, howbeit the ethanol oxidation reaction (EOR) sluggish kinetic is one of the essential challenges toward the commercialization of DEFCs. Herein, we introduce bimetallic catalyst on CoNiO 2 modified reduced graphene oxide (rGO) to completely exploit the advantages of nano-surface structures as well as the reduction of Pt and Pd loading in fuel cells. With the combined advantages of PtPd, CoNiO 2 and rGO, a significant enhancement in electrocatalytic behavior, stability and CO poisoning tolerance of PtPd have been observed. Regarding the implications, PtPd/CoNiO 2 /rGO is greatly preferable than Pt/CoNiO 2 /rGO and Pd/CoNiO 2 /rGO in terms of high electroactive surface area (ECSA), electro-catalytic activity, and lower onset potential (E ons) towards the EtOH oxidation in alkaline media. Furthermore, the chronoamperometry curve (CA) illustrated 77% after 3600 s which is dramatically soared compared with the other electrodes (≤40%), demonstrating the high stability of the PtPd bimetallic nanoparticle electrocatalyst. Ultimately, PtPd/CoNiO 2 /rGO nanocomposite is found to be an excellent anode electrocatalyst for application in DEFCs. • Pt, Pd and PtPd on CoNiO 2 /rGO as an active anodic electro-catalysts for application in DEFC. • PtPd/CoNiO 2 /rGO has significantly high current density and excellent catalyst stability. • A good anti CO-poisoning capability is obtained by PtPd/CoNiO 2 /rGO toward EOR. [ABSTRACT FROM AUTHOR]

In this study, a DEFC with an anion-exchange membrane is investigated to evaluate fuel utilization both theoretically and experimentally. The effects of variations in the input fuel temperature and fuel concentration on fuel utilization and power density were analyzed through sensitivity analysis. To this end, for different test conditions containing initial conditions, increasing the input fuel temperature and oxygen blowing to the cathode with fuel circulation, ethanol utilization factor and maximum power density were calculated. The findings revealed increasing the fuel temperature and oxygen blowing led to an increase in the ethanol utilization factor from 66.92% to 85.15% and 73.54%. Moreover, maximum power density was increased from 16.2 to 17.5 and 22.5 mWcm−2 for increasing the fuel temperature and oxygen blowing states. According to the results, it was proved that increasing the input fuel temperature and oxygen-blowing conditions had a contradictory impact on the performance analysis. As a solution, a new parameter named δ is introduced to conduct a more accurate performance analysis of DEFC. This parameter indicates the amount of produced power per unit of fuel consumption. The results demonstrated that parameter δ was increased from 0.14 to 0.21 and 0.31 mWcm−2 for increasing the fuel temperature and oxygen blowing states. [Display omitted] [ABSTRACT FROM AUTHOR]

Nitrogen-doped graphene oxide (N-doped GO), prepared by a facile hydrothermal reaction of GO with melamine as nitrogen source was studied as a filler in chitosan (CS) based anion exchange membranes (AEM) used in alkaline anion exchange membrane fuel cells. The structures and functional properties of the N-doped synthesized fillers (N level as high as 29.34 at.%) and produced CS-based AEMs were investigated by XPS, SEM, FTIR, XRD analysis, as well as, ion exchange capacity, tensile strength, ethanol permeability, alkali uptake, swelling ratio and cell performance tests. The as-obtained CS-based AEMs with 0.01 wt% N-doped GO filler have achieved a maximum power density of 149 ± 2.2 mW cm−2 at 80 °C, which is significantly higher than that of the benchmark commercial FAA Fumapem® and polybenzimidazole with values of 11 and 60 mW cm−2, respectively. The results demonstrate that the obtained membranes are promising AEM candidates for direct alkaline alcohol fuel cell applications. [ABSTRACT FROM AUTHOR]

As in many other electrochemical energy‐converting systems, the flexible direct ethanol fuel cells rely heavily on high‐performance catalysts with low noble metal contents and high tolerance to poisoning. In this work, a generic dealloying procedure to synthesize nanoporous multicomponent anodic and cathodic catalysts for the high‐performance ethanol fuel cells is reported. On the anode side, the nanoporous AlPdNiCuMo high‐entropy alloy exhibits an electrochemically active surface area of 88.53 m2 g−1Pd and a mass activity of 2.67 A mg−1Pd for the ethanol oxidation reaction. On the cathode side, the dealloyed spinel (AlMnCo)3O4 nanosheets with no noble metals demonstrate a comparable catalytic performance as the standard Pt/C for the oxygen reduction reaction, and tolerance to high concentrations of ethanol. Equipped with such anodic and cathodic catalysts, the flexible solid‐state ethanol fuel cell is able to deliver an ultra‐high energy density of 13.63 mWh cm−2 with only 3 mL ethanol, which is outstanding compared with other similar solid‐state energy devices. Moreover, the solid‐state ethanol fuel cell is highly flexible, durable and exhibits an inject‐and‐run function. [ABSTRACT FROM AUTHOR]

Following their successful utilization as novel bioanodes in Microbial Fuel Cells (MFCs), Layered Double Hydroxide (LDH) were tested in the present investigation, as promising cathodes to reduce electrons coming from oxidation of organic matter in the anode compartment, in the presence of oxygen used as successful oxidant. Therefore, the LDH samples Ni3Al-LDH with the ionic ratio Ni2+/Al3+ equal to 3, were synthesized and added by adsorption to Carbon Felt (CF) fibres. They were then stored separately in three electrolyte solutions KCl, NiCl2 and AlCl3 used as catholytes in the MFCs. Effects of the active cationic sites located inside the Ni3Al-LDH on these electrolytes, were discussed in terms of energies produced by these MFCs. The structure and morphology of the synthesized LDH, were studied by using the analytical techniques XRD, FTIRS and SEM, while the electrode performances of the LDH-electrodes were investigated with the electrochemical methods CV and EIS. It was revealed that the CF modified with Ni3Al-LDH cathode and conditioned in the NiCl2 electrolyte solution yielded the highest energy harvesting for the MFC (i.e. 3.2 µW/cm2). This power density output was similar to previous clean one-compartment MFC. However, it was less expensive than an Enzymatic Fuel Cell (45 µW/cm2), making in evidence the highest cost of the material. Thus, by taking into account these encouraging findings, the low cost materials used in MFCs held great promise for practical application in electrochemical power devices and therefore fruit waste treatment. Abbreviations: ACFC: Air Cathode Fuel Cell; ADEFC: Alkaline Direct Ethanol Fuel Cell; AFC: Alcaline Fuel Cell; BET: Brunauer–Emmett–Teller; BFC: Biological Fuel Cell; CF: Carbon Felt; CV: Cyclic Voltammetry; DGFC: Direct Glucose Fuel Cell; DMFC: Direct Methanol Fuel Cell; EFC: Enzymatic Fuel Cell; EIS: Electrochemical Impedance Spectroscopy; FC: Fuel Cell; FTIR: Fourier Transform Infra Red spectroscopy; LDH: Layered Double Hydroxide; MEC: Microbial Electrolysis Cell; MFC: Microbial Fuel Cell; Mg-Al- CO 3 2 -LDH: Layered Double Hydroxide Magnesium-Aluminium-Carbonate; Ni-Al-LDH: Layered Double Hydroxide Nickel-Aluminium; OCP: Open Circuit Potential; SEM: Scanning Electron Microscope; TG/DTA: ThermoGravimetric and Differential Thermal Analysis; XRD: X-Ray Diffraction. [ABSTRACT FROM AUTHOR]

Pt-Ru and Pt–Re and Pt-Ru-Re nanoparticles supported on functionalized multi-walled carbon nanotubes (f-MWCNT) were synthesized via modified polyol reduction method and tested thoroughly in a half cell and single direct ethanol fuel cell for ethanol electrooxidation in acidic medium. The MWCNTs were functionalized in a mixture of HNO 3 /H 2 SO 4 solution for depositing a more active metal alloy nanoparticle on support material. The alloy formation of bi-metallic and tri-metallic electrocatalysts were examined by XRD analysis and more clearly explained by FE-SEM element mapping. The TEM analyses reveal that electrocatalysts nanoparticles are well dispersed on f-MWCNT, with spherical shapes and nano sizes range of 1.5–4 nm. The electrochemical analyses by cyclic voltammetry and chronoamperometry measurements reveal that tri-metallic electrocatalyst Pt-Ru-Re (1:1:0.5)/f-MWCNT exhibits the highest electrocatalytic activity and stability towards ethanol electrooxidation among all the synthesized electrocatalysts. The same electrocatalyst as anode in single DEFC results in excellent performance in comparison to all other synthesized electrocatalysts, with a maximum power density of 9.52 mW/cm2 at a cell temperature of 30 °C. The bi-metallic Pt-Ru (1:1)/f-MWCNT and Pt–Re (1:1)/f-MWCNT produced power density of 7.48 mW/cm2 and 4.74 mW/cm2 at room temperature of 30 °C. The power density of DEFC enhanced 2.44 times, when cell operating temperature was increased from 30 °C to 80 °C using anode electrocatalyst Pt-Ru-Re (1:1:0.5)/f-MWCNT and keeping other parameters constant. The best result obtained in half cell and single DEFC using Pt-Ru-Re (1:1:0.5)/f-MWCNT electrocatalyst may be attributed to the synergistic effect of Pt, Ru and Re combined with bi-functional and ligand effects. • Functionalized f-MWCNTs proved to be excellent support material of electrocatalyst. • Re addition to Pt-Ru electrocatalyst enhanced ethanol electrooxidation kinetics. • Pt-Ru-Re (1:1:0.5)/f-MWCNT exhibits highest electrocatalytic activity for ethanol fuel. • Very low loading of anode Pt-Ru-Re (1:1:0.5)/f-MWCNT was used in DEFC study. [ABSTRACT FROM AUTHOR]

Pd 1 Nb 1 /C on different kinds of carbon black were prepared by a modified sol-gel method. The alkaline direct ethanol fuel cell (ADEFC) performance was performed first with the Pd 1 Nb 1 electrocatalysts and then by varying the fuel concentration. In CV, Pd 1 Nb 1 /Printex 6L (50:50 wt%) exhibited 2.2 times higher mass activity than that of the Pd/C (Alfa Aesar); their mass activities were 1300 and 590 mA mg Pd − 1 , respectively. The best performance for the ADEFC was obtained using Pd 1 Nb 1 /Printex 6L, which yielded a maximum power density and cell voltage of 28 mW cm−2 and 1.17 V, respectively. The Pd 1 Nb 1 /Printex 6L electrocatalyst exhibited a more negative onset potential for the CO stripping reaction. We suggest that the higher hydrophilicity (contact angle) and higher degree of disorder of Printex 6L (Raman) corroborates these results. In addition, both bifunctional and electronic effects operated on the electrocatalyst due to the presence of metal oxides and alloys of PdNb (XRD), respectively, in the synthesized electrocatalysts. Therefore, it was notable that the support has an essential role—as important as the cocatalyst—in the electrocatalytic performance. ● Pd1Nb1/C binary electrocatalysts supported on different carbon black to ADEFC. ● Pd1Nb1/Printex 6L exhibited 2.2 times higher activity compared to Pd/C (Alfa Aesar©). ● The best performance for the ADEFC was obtained using Pd1Nb1/Printex 6L. ● This performance indicates an excellent energy efficiency of approximately 92%. ● The Printex 6L showed here as the best support than other carbon blacks. [ABSTRACT FROM AUTHOR]

The electrocatalytic performance of Polypyrrole-Copper oxide particles modified carbon paste electrode (Cu 2 O/PPy/CPE) for electrocatalytic oxidation of ethanol was reported for the first time in alkaline media. The composite Cu 2 O/PPy was prepared using a facile approach consisting on the deposition of Polypyrrole film on CPE using galvanostatic mode then followed by the deposition of Copper particles at a constant potential. Scanning electron spectroscopy (SEM), infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the structural and electrochemical properties of the Cu 2 O/PPy/CPE and to explain the mechanism of electrooxidation of ethanol. The experimental parameters that influence the electrooxidation of ethanol were investigated and optimized. Our findings suggest that the electrodeposition of Copper particles on Polypyrrole film enhanced the catalytic activity towards the ethanol oxidation with a peak current density of 2.25 mA cm−2 at 0.8 V vs Ag/AgCl, which is 2.6 times higher than the peak current density obtained by PPy/CPE electrode. It important to note that the saturation limit reaches a value of 5 M. To summarize, the good catalytic activity, stability and easy preparation make the Cu 2 O/PPy composite as an excellent electrocatalyst for ethanol oxidation. Image 1 • Copper oxide particles/Polypyrrole (Cu 2 O/PPy) novel catalyst was prepared via electrochemical method. • Cu 2 O/PPy displayed good catalytic performance for the electrooxidation of ethanol. • The electrooxidation of ethanol on the Cu 2 O/PPy follow the C1 pathway. [ABSTRACT FROM AUTHOR]

High cost and poor durability of Pt-based electrocatalysts are the main challenges for future commercialization of direct ethanol fuel cells (DEFCs). In the present work, a stable and effective Pt/Ti 0.8 W 0.2 O 2 electrocatalyst toward ethanol electrooxidation reactions (EORs) was prepared by utilizing the attributes of noncarbon catalyst supports and low Pt loading. The 18.5 wt % Pt/Ti 0.8 W 0.2 O 2 electrocatalyst was successfully fabricated through a simple and rapid microwave-assisted polyol route (ethylene glycol was used as a reducing agent). In comparison with a conventional 20 wt % Pt/C electrocatalyst, the as-prepared 18.5 wt % Pt/Ti 0.8 W 0.2 O 2 electrocatalyst resulted in much lower onset potential, higher I f / I b value, and superior stability toward EOR, which can be ascribed to the synergistic effect between Pt nanocatalyst and the Ti 0.8 W 0.2 O 2 catalyst support. Therefore, these findings imply that 18.5 wt % Pt/Ti 0.8 W 0.2 O 2 is a promising anodic electrocatalyst and possesses the ability to replace Pt/C electrocatalysts in the future. [ABSTRACT FROM AUTHOR]

This paper presents an analytical solution to calculate the mole fraction of the major species involved in the oxidation of ethanol on the anode side, and the reduction of oxygen on the cathode side of a direct ethanol full cell. The equations of the species are solved using two mathematical tools: Separation of variables and Laplace transform. The solutions obtained with the two methods are equivalent and describe the mole fraction of chemical species. The results obtained with the analytical solution were compared with the data obtained with the two-dimensional model, solved numerically with the finite difference method in space and Runge-Kutta method in time. The results of mole fraction of the species obtained through the analytical solution are used to calculate, at a lower cost, the overpotential losses and the direct ethanol fuel cell voltage. The results obtained are in accordance with the experimental data found in the literature for the catalysts Pt-Re-Sn/t-MWCNTs and Pt-Re-Sn/MCN. [ABSTRACT FROM AUTHOR]

This manuscript describes the synthesis and structural/morphological characterization of Sb 2 O 3 nanostructures modified by Pd nanoparticles and its use as a Fuel Cells electrocatalyst and as non-enzymatic amperometric sensor for ethanol. Interesting Sb 2 O 3 surface modifications due to Pd nanoparticles were observed, such as the loss of spherical shape and the appearance of superficial pores. As an electrocatalyst Pd/Sb 2 O 3 exhibited two times higher catalytic activity at a constant potential than carbon-supported Pd nanoparticles to oxidize ethanol in alkaline media (current densities of 348 μA cm−2 and 165 μA cm−2 at −0.3 V vs. Ag/AgCl 3.0 M, respectively). To the extent of our knowledge this result is the first one describing such an enhancement of the Pd activity only by means of alteration of the support. Moreover, as an amperometric sensor for ethanol, the electrode showed a linear response in a broad range of concentrations with a detection limit of 0.10 μM and sensitivity between of 1.47 to 1.00 μA mM−1 cm−2. The combined findings presented in this work revealed Pd/Sb 2 O 3 can be a promising material for Direct Ethanol Fuel Cells and as a non-enzymatic amperometric sensor for ethanol. Unlabelled Image • Functionalization of Sb 2 O 3 spheres with Pd nanoparticles • Increase in catalytic activity of Pd due to interactions with the Sb 2 O 3 support • Pd/Sb 2 O 3 electrocatalyst exhibits twice the activity of Pd/C to oxidize ethanol. • Development of a Pd/Sb 2 O 3 based ethanol sensor [ABSTRACT FROM AUTHOR]

The preparation of polyelectrolytes based on crosslinked poly(vinyl alcohol) (PVA) and chitosan (CS) was considered as a feasible alternative to develop highly functionalised, cost-effective and eco-friendly membranes for proton exchange fuel cell technologies. CS/PVA-based membranes were combined with sulfosuccinic acid (SSA) as crosslinking and sulfonating agent, and glycerol (GL) to promote flexibility and favour their manageability. The chemical structure, the thermo-oxidative behaviour, the ethanol uptake, the electric, the proton conductivity, and the performance in direct ethanol fuel cell (DEFC) were assessed. In general, all the CS/PVA-based polyelectrolytes showed a synergetic increase of thermo-oxidative stability, appropriate absorption and diffusion of ethanol and good proton conductivity, suitable for the typical service conditions of fuel cells. The GL in the membranes reacted with SSA, reduced the ethanol absorption, the diffusion coefficient and the proton conductivity, but acted as a plasticiser that increased the ductile manageability of the polyelectrolytes to be mounted on the membrane-electrode assembly (MEA). Higher presence of CS and higher proportion of GL in the polyelectrolyte, improved the material performance in the DEFC. In particular, the crosslinked polyelectrolyte 40CS/PVA/SSA/20GLwith a 40%wt. of CS referred to PVA, and a 20%wt. of GL referred to CS, showed a suitable behaviour in the DEFC test, with a maximum value of power density of 746 mW·cm−2. [ABSTRACT FROM AUTHOR]

The electrocatalysts with superior activity and stability for ethanol oxidation reaction (EOR) are of critical importance for the development of direct ethanol fuel cells (DEFCs). Herein, an effective multistep wet-chemical method has been developed to controllably synthesize hollow echinus-like shaped Pd-based trimetallic nanospheres (Au@PdAgNSs) and corresponding reduced graphene oxide supported Au@PdAgNSs nanocomposite (Au@PdAgNSs/rGO). The results of various physical characterizations indicate that the as-prepared Au@PdAgNSs is a porous and hollow echinus-shaped core-shell structure with gold as the core and PdAg alloy as the shell. Through the CA and CV measurements the resultant Au@PdAgNSs/rGO demonstrated excellent electrocatalytic activity and stability towards ethanol oxidation in an alkaline medium as compared to a commercial Pd/C catalyst, making it very attractive for application in alkaline DEFCs. Image 1 • Hollow echinus-like Au@PdAgNSs decorated reduced graphene oxide using multistep wet-chemical method were prepared. • Au@PdAgNSs/rGO exhibited superior performance for ethanol electro-oxidation in alkaline media. • The excellent performance of Au@PdAgNSs/rGO derived from unique morphology and combination with rGO. [ABSTRACT FROM AUTHOR]

• When the height shrinkage rate of the channel is controlled at 55–77%, the current density increases greatly. • The width shrinkage rate has little effect on the performance of the DEFC. • Increasing the height shrinkage rate is beneficial to the discharge of water. • It has an adverse impact on the uniformity of current density distribution when the channel width shrinks. Design and optimization of channel has significant effects on mass and heat transfer and comprehensive performance of fuel cells. In this study, a new type of direct ethanol fuel cell with tubular structure is proposed, and the effects of different channel height and width shrinking rate on the current density, water distribution, temperature distribution and pressure distribution on the cathode side of the cell are studied by computational fluid dynamics (CFD). The results indicate that the height shrinking rate is beneficial to increase the pressure drop on the cathode side and improve the removal ability of water, leading to better fuel cells, and the height shrinking rate is 55–77%, the performance of DEFC is improved the best. When the height shrinking rate is 77%, its optimizations have a power density growth rate of 34%, which is about 31.5 mW/cm2.The width shrinking rate has little effect on the fuel cell, reducing the power density to 23.5 mW/cm2. This phenomenon is due to that the reduction of the Catalytic area leads to the oxygen gradient distribution in the Electrode layer, which promotes the discharge of cathode water, but leads to insufficient oxygen in the central region of the fuel cell membrane electrode, resulting in the decrease of current density. [ABSTRACT FROM AUTHOR]

Highlights • Design and fabrication of BPP is further introduced based on our previous study. • Round corner and clearance of moulds play important role in maximum channel height. • Channel dimensions are selected by formability model and reaction efficiency. • Channel height, channel thickness and effect of blank holder are discussed. • Performance of single cell and short stack is tested to evaluate method reliability. Abstract This study offers an efficient design method of flow channels of metallic bipolar plates (BPPs) to improve manufacturing technique of BPPs and maximize power density in proton exchange membrane (PEM) fuel cells. Stamped thin metallic BPPs with anticorrosive and conductive coating are promising candidates for replacing conventional carbon-based BPPs. Nevertheless, unlike carbon-based BPPs, the flow channel design of metallic BPPs should take into account not only the reaction efficiency, but also formability due to the possible rupture of the metallic channel during the micro-forming process. In our previous study, a forming limit model was first proposed to predict the maximum allowable channel height by the forming process. This study is conducted to further propose the method of the design and fabrication of metallic BPPs based on the numerical model. In order to determine channel geometry design from formability perspective, response surface method is utilized to build a formability model. Combining the formability model and reaction efficiency, flow field design for metallic BPPs (channel width of 0.9 mm, rib width of 0.9 mm, channel depth of 0.4 mm and radius of 0.15 mm) is proposed. Experiments on BPP fabrication and assembled 20-cell fuel cell testing are conducted to observe forming quality of micro channel and output performance on the real fuel cell. It is shown that the stamping force grows with increasing channel depth in a nonlinear manner and a blank holder is needed to eliminate the sheet wrinkle in the forming process. The uniformity of the voltage distribution in the 1000 W-class stack further proves the reliability of metallic BPPs designed by our method. The methodology developed is beneficial to the fabrication management of metallic BPPs and effective supplement to the channel design principle for PEM fuel cells. [ABSTRACT FROM AUTHOR]

The development of active catalyst for ethanol electrooxidation is a key to improving the power output of direct ethanol fuel cells (DEFCs). In this study, Pt-Sn was supported on SiO 2 embedded carbon nanofiber as active anode catalyst for DEFC by expecting positive interactions between Pt-Sn-SiO 2 . The composite catalyst, Pt 3 Sn 1 /SECNF, showed highest mass activity for the ethanol electrooxidation, which was 3.7 times higher than the activity of the commercial Pt/C (Pt/C com ). The maximum power density of DEFC single cell with the composite catalyst was 3.5 times higher than that with Pt/C com . [ABSTRACT FROM AUTHOR]

Background: Concentration and purification of ethanol and other biofuels from fermentations are energy-intensive processes, with amplified costs at smaller scales. To circumvent the need for these processes, and to potentially reduce transportation costs as well, we have previously investigated bio-hybrid fuel cells (FCs), in which a fermentation and FC are closely coupled. However, long-term operation requires strictly preventing the fermentation and FC from harming each other. We introduce here the concept of the vapor-fed bio-hybrid FC as a means of continuously extracting power from ongoing fermentations at ambient conditions. By bubbling a carrier gas (N2) through a yeast fermentation and then through a direct ethanol FC, we protect the FC anode from the catalyst poisons in the fermentation (which are non-volatile), and also protect the yeast from harmful FC products (notably acetic acid) and from build-up of ethanol. Results: Since vapor-fed direct ethanol FCs at ambient conditions have never been systematically characterized (in contrast to vapor-fed direct methanol FCs), we first assess the effects on output power and conversion efficiency of ethanol concentration, vapor flow rate, and FC voltage. The results fit a continuous stirred-tank reactor model. Over a wide range of ethanol partial pressures (2-8 mmHg), power densities are comparable to those for liquid-fed direct ethanol FCs at the same temperature, with power densities >2 mW/cm2 obtained. We then demonstrate the continuous operation of a vapor-fed bio-hybrid FC with fermentation for 5 months, with no indication of performance degradation due to poisoning (of either the FC or the fermentation). It is further shown that the system is stable, recovering quickly from disturbances or from interruptions in maintenance. Conclusions: The vapor-fed bio-hybrid FC enables extraction of power from dilute bio-ethanol streams without costly concentration and purification steps. The concept should be scalable to both large and small operations and should be generalizable to other biofuels and waste-to-energy systems. [ABSTRACT FROM AUTHOR]

Alkaline direct ethanol fuel cells (DEFC), which convert the chemical energy stored in ethanol directly into electricity, are one of the most promising energy-conversion devices for portable, mobile and stationary power applications, primarily because this type of fuel cell runs on a carbon-neutral, sustainable fuel and the electrocatalytic and membrane materials that constitute the cell are relatively inexpensive. As a result, the alkaline DEFC technology has undergone a rapid progress over the last decade. This article provides a comprehensive review of transport phenomena of various species in this fuel cell system. The past investigations into how the design and structural parameters of membrane electrode assemblies and the operating parameters affect the fuel cell performance are discussed. In addition, future perspectives and challenges with regard to transport phenomena in this fuel cell system are also highlighted. [ABSTRACT FROM AUTHOR]

[Display omitted] • N, S, and SN-doped graphene materials were synthetized. • Supporting Co 3 O 4 on GMs can increase electrocatalytic activity towards ORR. • ORR mechanism was studied by Tafel plots. • DEFC tests show better results for Co/SN-rGO compared to commercial Pt/C. Oxygen reduction reaction (ORR) is one of the key features for the efficient functioning of several energy conversion devices such as fuel cells, appearing the necessity of development of new low-cost catalyst materials. Heteroatom-doped carbon materials have attracted attention in this field due to its physicochemical and electronic properties. In this work, a nitrogen and sulfur doped material with anchored Co 3 O 4 nanoparticles (Co/SN-rGO) is proposed as cathode catalyst for direct ethanol fuel cells (DEFCs) and results are compared with different doped graphene nanomaterials (GMs). The effect of the heteroatoms and cobalt oxide nanoparticles in the final efficiency was studied. Synthesized materials were characterized and the activity of Co/SN-rGO and GMs for the ORR was studied. Co/SN-rGO presents high ORR performance in terms of onset potential (E onset), 0.86 V (vs RHE) and half-wave potential (E 1/2) 0.72 V (vs RHE). Tafel analysis shows 60 mV dec-1 at low overpotential for potential dependent ORR mechanism. Besides, when Co/SN-rGO performance is evaluated in a DEFC using a fuel cell test station, main results indicate higher catalytic activity, stability, and ethanol tolerance of Co/SN-rGO in comparison to a carbon-supported Pt catalyst. [ABSTRACT FROM AUTHOR]

Fuel cells have been seen as a viable alternative to fossil fuel engines, mainly driven by environmental restrictions. In this work, a direct ethanol fuel cell is modeled using a dynamic model, which considers fuel and air flow, anode and cathode losses, membrane, multifunctional catalysts (P t / C , P t − R u / C and P t − S n / C), temperature, and the variation of species concentration in relation to the current density, since the cell operation is influenced by them. The equations are discretized using the finite difference method and the integration is performed using the Rosenbrock method. The results obtained for the flow using the dynamic model developed reasonably agree with data found in the literature. The molar fractions of the species shown contribute to the understanding of the behavior of the reactive flow that occurs inside an ethanol fuel cell. • Dynamic models are best suited for analyzing DEFCs. • The flow is solved using the Rosenbrock finite differences method. • Multifunctional catalysts are more suitable for DEFCs. • DEFC solution for temperature and mole fraction of species. [ABSTRACT FROM AUTHOR]

In this paper, we develop a mathematical model to analyze a direct ethanol fuel cell (DEFC). The three-dimensional model is able to predict the flow on all layers of the fuel cell and allow a better analysis of physical and chemical phenomena that occur inside it. In addition, the calculation of mole fraction of species allows one to observe that the diffusion layer has great influence on mass transfer of fuel between the input channel and the catalyst layer. Numerical simulation of reactive flow was made based on the central finite difference method. The equations were integrated in time using the simplified Runge-Kutta multistage scheme. The results obtained are in agreement with the experimental data found in the literature, for different feed concentrations of ethanol and for different operating temperatures of the cell. In this way, the paper contributes to the development of a model for direct ethanol fuel cells, taking into account all losses overpotentials at the anode and the cathode, providing a better understanding of the physical and chemical behavior inside the cell, and on the conversion of chemical energy into electrical energy. [ABSTRACT FROM AUTHOR]

Conventionally, two critical issues that limit the steady-state discharge of alkaline liquid fuel cells are the pH-dependant problem at anode and the carbonation problem at cathode. The present work addresses these two issues by reporting an anion-exchange membrane direct liquid fuel cell that uses a pH-insensitive fuel, formate, as the reductant, and a CO 2 -free reactant, hydrogen peroxide, as the oxidant, referred to as anion-exchange membrane direct formate-peroxide fuel cell (AEM DFPFC). Theoretically, the cell voltage of the AEM DFPFC can be as high as 1.92 V. It has been experimentally demonstrated that a conceptual half-hour constant-current discharge of the AEM DFPFC almost remains unchanged, even eliminating the supporting electrolytes at both anode and cathode. In contrast, an anion-exchange membrane direct ethanol fuel cell (AEM DEFC) shows a sharp decline in constant discharge within a few seconds. [ABSTRACT FROM AUTHOR]

Carbon supported nanostructured palladium or palladium alloys are considered the best performing anode electrocatalysts currently employed in alkaline electrolyte membrane direct ethanol fuel cells (AEM-DEFCs). High initial peak power densities are generally obtained as Pd preferentially favors the selective oxidation of ethanol forming acetate thus avoiding strongly poisoning intermediates such as CO. However, few studies exist that investigate DEFC performance in terms of both energy efficiency and discharge energy density, as well as power density depending on the concentration of fuel. In this paper we have determined such parameters for room temperature air breathing AEM-DEFCs equipped with Pd based anodes, anion exchange membranes and FeCo/C cathode electrocatalysts. Combined with the optimization of the fuel composition a maximum energy efficiency of ≈7 % was obtained for this AEM-DEFC. Such a performance suggests that devices of this type are suitable for supplying low power applications such as small portable electronic devices. [ABSTRACT FROM AUTHOR]

In this paper, a catalyst of hollow PdCu alloy nanocubes supported on nitrogendoped graphene support (H-PdCu/ppy-NG) is successfully synthesized using a simple onepot template-free method. Two other catalyst materials such as solid PdCu alloy particles supported on this same nitrogen-doped graphene support (PdCu/ppy-NG) and hollow PdCu alloy nanocubes supported on the reduced graphene oxide support (H-PdCu/RGO) are also prepared using the similar synthesis conditions for comparison. It is found that, among these three catalyst materials, H-PdCu/ppy-NG gives the highest electrochemical active area and both the most uniformity and dispersibility of H-PdCu particles. Electrochemical tests show that the H-PdCu/ppy-NG catalyst can give the best electrocatalytic activity and stability towards the ethanol electrooxidation when compared to other two catalysts. Therefore, H-PdCu/ppy-NG should be a promising catalyst candidate for anodic ethanol oxidation in direct ethanol fuel cells. [ABSTRACT FROM AUTHOR]

A 2 μm thick layer of TiO2 nanotube arrays was prepared on the surface of the Ti fibers of a nonwoven web electrode. After it was doped with Pd nanoparticles (1.5 mgPd cm−2), this anode was employed in a direct alcohol fuel cell. Peak power densities of 210, 170, and 160 mW cm−2 at 80 °C were produced if the cell was fed with 10 wt % aqueous solutions of ethanol, ethylene glycol, and glycerol, respectively, in 2 M aqueous KOH. The Pd loading of the anode was increased to 6 mg cm−2 by combining four single electrodes to produce a maximum peak power density with ethanol at 80 °C of 335 mW cm−2. Such high power densities result from a combination of the open 3 D structure of the anode electrode and the high electrochemically active surface area of the Pd catalyst, which promote very fast kinetics for alcohol electro-oxidation. The peak power and current densities obtained with ethanol at 80 °C approach the output of H2-fed proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]