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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]

Direct ethanol fuel cells (DEFCs) have drawn attention for their simplicity, rapid start-up, high power density and environmental friendliness. Despite these advantages, the widespread application of DEFCs faces challenges, primarily due to the inadequate performance of anode and cathode catalysts. Pd-based materials have shown exceptional catalytic activity for both the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR). Alloying noble metals with rare earth elements has emerged as an effective strategy to further enhance the catalytic activity by modulating the electronic structure. In this study, we synthesized a series of palladium-rare earth (Pd3RE) alloys supported on carbon to serve as bifunctional catalysts that efficiently promote both ORR and EOR. Compared to Pd/C, the Pd3Tb/C catalyst exhibits 3.1-fold and 1.8-fold enhancement in activity for ORR and EOR, respectively. The charge transfer in the Pd3Tb/C results in an electron-rich Pd component, thereby weakening the binding energy with oxygen species and facilitating the two reactions. [ABSTRACT FROM AUTHOR]

ABSTRACT The rational design of noble metal‐free electrocatalysts represents one of the basic stones for fuel cell development. With the exploration of eco‐friendly nanomaterials for the investigated alcohol oxidation process, nickel‐based electrodes have been recognized as the most auspicious anodes with promoted activity and stability. In this work, a series of NiCo2O4 nanoparticles were deposited onto graphite sheets (NiCo2O4/T) introducing varied proportions of cobalt oxide species. Co‐precipitation protocol of the respective metallic hydroxides onto the carbonaceous support was followed with consecutive annealing in an air atmosphere at 400°C. The fabricated mixed metallic oxide nanopowder was physically studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X‐ray analysis (EDX), X‐ray photoelectron spectroscopy (XPS), and selected area electron diffraction (SAED). Uniformly arranged nanoparticles were observed on graphite surface as evidenced by SEM and TEM. The cubic lattice structure of formed NiCo2O4 crystals was also confirmed by XRD through the defined peaks of binary metallic oxides clarifying their successful preparation scheme. The electrocatalytic properties of these NiCo2O4/T nanocatalysts were evaluated for oxidizing ethanol molecules in basic solution. Pronounced oxidation current densities were remarkably measured at NiCo2O4/T electrodes in relation to that at NiO/T. Differing the introduced cobalt oxide content into the synthesized nanocatalyst significantly controlled its catalytic performance. NiCo2O4/T‐20 exhibited the highest activity and stability among the prepared nanomaterials. Much decreased charge transfer resistances were also recorded at this electrode demonstrating its promoted electron transfer characteristics. This work could provide a reasonable route for the simple synthesis of comparable transition metallic oxides with promising attitudes for energy generation purposes. [ABSTRACT FROM AUTHOR]

Developing catalysts based on non-precious metals is crucial for the electrochemical oxidation of ethanol, a pivotal anodic reaction in direct ethanol fuel cells. In this study, we crafted a series of Mn oxyhydroxides/Ni catalysts via a straightforward electrochemical deposition of Mn onto Ni foam. By carefully modulating the concentration of Mn2+ during electrodeposition, we achieved a tunable surface Mn/Ni ratio and Mn–Ni synergy. It is observed that with increasing Mn/Ni ratio, the electrochemically active surface area (ECSA) increases monotonously, while the intrinsic activity increased first and then decreased. Consequently, electrodes with surface ratios of 6.1 and 8.6 exhibit relatively lower intrinsic activity but higher ECSA, ultimately attaining the highest apparent activity (94–98 mA cm−2 peak current density at 1.50 V vs. reversible hydrogen electrode) for ethanol oxidation. This work provides an accessible approach to tailor Mn–Ni synergy, paving the way for the design of highly efficient catalysts for electrochemical ethanol oxidation. [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]

The design of efficient electrocatalysts for ethanol oxidation is essential for commercializing direct ethanol fuel cells (DEFCs). In this strategy, a mesoporous carbon microsphere (MC) was first synthesized by inverting the micro-emulsion technique. The MC@Au/Pd catalyst with a particular core-shell structure was obtained by utilizing mesoporous carbon as a core to load the Au/Pd layer. The novelty of the MC@Au/Pd catalyst with specialized core-shell structures lies not only in the high specific surface area inherited from the carbon core but also in the strong electronic interactions caused by the lattice mismatch between the core (Au) and shell (Pd) atoms. Particularly, electrochemical measures demonstrated that the Au/Pd catalyst exhibits superior catalytic activity toward the ethanol oxidation reaction (EOR) compared with commercial Pd/C catalysts. This is mainly due to the high specific surface area and mesoporous pore size inherited from the core carbon microspheres. In addition, the mesoporous carbon core and Au/Pd shell in the well-organized core-shell catalyst (MC@Au/Pd) influence the catalytic activity for ethanol oxidation by adjusting the electronic structure of Pd. [Display omitted] • A novelty carbon core/Au–Pd shell structure catalyst was first synthesized. • The carbon core provides an abundance of mass transfer channels for EOR. • The well-organized catalyst exhibit enhanced catalytic activity for EOR. [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) have been widely considered as a feasible power conversion technology for portable and mobile applications. The economic feasibility of DEFCs relies on two conditions: a notable reduction in the expensive nature of precious metal electrocatalysts and a simultaneous remarkable improvement in the anode's long-term performance. Despite the considerable progress achieved in recent decades in Pt nanoengineering to reduce its loading in catalyst ink with enhanced mass activity, attempts to tackle these problems have yet to be successful. During the ethanol oxidation reaction (EOR) at the anode surface, Pt electrocatalysts lose their electrocatalytic activity rapidly due to poisoning by surface-adsorbed reaction intermediates like CO. This phenomenon leads to a significant loss in electrocatalytic performance within a relatively short time. This review provides an overview of the mechanistic approaches during the EOR of noble metal-based anode materials. Additionally, we emphasized the significance of many essential factors that govern the EOR activity of the electrode surface. Furthermore, we provided a comprehensive examination of the challenges and potential advancements in electrocatalytic EOR. [ABSTRACT FROM AUTHOR]

The development of highly efficient electrocatalysts for the ethanol oxidation reaction (EOR) is essential for the commercialization of direct ethanol fuel cells, yet challenges remain. In this study, a one‐pot solution‐phase method to synthesize Pd nanowire networks (NNWs) with very high surface‐to‐volume ratio having numerous twin and grain boundaries is developed. Using the same method, the Pd lattice is further engineered by introducing Ag and Cu atoms to produce AgPd, and CuPd alloy structure which significantly shifts the Pd d‐band center upward and downward, respectively due to strain and ligand effects. Theoretical analysis employing density functional theory (DFT) demonstrates that such modification of the d‐band center significantly influences the adsorption energies of reactants on the catalytic surface. Owing to their notably high surface‐to‐volume ratio and the presence of multiple twin and grain boundaries, Pd NNWs demonstrate significantly enhanced electrocatalytic activity toward EOR, ≈7.2 times greater than that of commercial Pd/C. Remarkably, compared to Pd NNWs, AgPd, and CuPd NNWs display enlarged and reduced electrocatalytic activity toward EOR, respectively. Specifically, Ag4Pd7 NNWs achieve a remarkable mass activity of 9.00 A mgpd−1 for EOR, which is 13.6 times higher than commercial Pd/C. [ABSTRACT FROM AUTHOR]

The emergence of direct ethanol fuel cells (DEFCs) as a promising future power generation system stems from their eco-friendly nature and their safety for human consumption of ethanol fuels, aligning with the requirements of SDG-7. Furthermore, DEFCs offer extensive design flexibility, ranging from single-cell configurations to large multi-cell setups suitable for various applications such as portable devices, transportation, and stationary power systems. This versatility has led to a surge in research and development efforts from both academia and industry. However, the fundamental barrier to the widespread commercialization of DEFCs lies in obtaining high-activity redox reactions of catalysts, which involve ethanol oxidation and oxygen reduction. Conventional platinum-based catalysts are vulnerable to poisoning from intermediate species produced during ethanol oxidation. This review provides a detailed assessment of current catalyst modifications in DEFCs, focusing on material catalyst improvements in catalyst characterization and electrocatalytic activity to enhance overall cell performance. Thus, this research focuses on exploring updated modifications of catalyst materials that are robust, durable, and possess high catalytic activity, thereby aiding the redox reactions involved in ethanol energy conversion. [ABSTRACT FROM AUTHOR]

Abstract Direct ethanol fuel cells (DEFCs) have been widely considered as a feasible power conversion technology for portable and mobile applications. The economic feasibility of DEFCs relies on two conditions: a notable reduction in the expensive nature of precious metal electrocatalysts and a simultaneous remarkable improvement in the anode's long-term performance. Despite the considerable progress achieved in recent decades in Pt nanoengineering to reduce its loading in catalyst ink with enhanced mass activity, attempts to tackle these problems have yet to be successful. During the ethanol oxidation reaction (EOR) at the anode surface, Pt electrocatalysts lose their electrocatalytic activity rapidly due to poisoning by surface-adsorbed reaction intermediates like CO. This phenomenon leads to a significant loss in electrocatalytic performance within a relatively short time. This review provides an overview of the mechanistic approaches during the EOR of noble metal-based anode materials. Additionally, we emphasized the significance of many essential factors that govern the EOR activity of the electrode surface. Furthermore, we provided a comprehensive examination of the challenges and potential advancements in electrocatalytic EOR. Graphic abstract

Efficient ethanol oxidation reaction (EOR) catalysts with anti‐poisoning ability and high selectivity are in high demand for the widespread application of direct ethanol fuel cells (DEFCs). Here, the PdSnW ternary alloy nanoparticles are synthesized by a facile solvothermal method and exhibit an enhanced EOR catalytic performance. CO stripping experiment, X‐ray photoelectron spectroscopy and in situ Fourier transform infrared are employed to study the correlation between catalyst structure and EOR catalytic performance. The oxyphilic Sn and W not only provide dangling O−H bond, accelerating the subsequent oxidation of adsorbed intermediate CO species, but also moderate the electron state of Pd, enhancing the adsorption of CH3CH2OH, thus resulting in the promotion of C−C bond cleavage and an increased C1 selectivity. As a consequence, PdSnW alloy nanoparticle catalyst exhibit a better stability and a higher mass activity than those of Pd/C, PdSn and PdW, respectively. This work not only offers novel insights to strategically design highly efficient electrocatalysts for ethanol oxidation, but also further clarifies the inherent structure‐activity relationship. [ABSTRACT FROM AUTHOR]

One of the main challenges with passive direct ethanol fuel cells (DEFCs) is ethanol transport management since the liquid ethanol is supplied to the anode compartment by natural processes including convection and diffusion with a low cell operating condition. The significant layer in the cell is the diffusion layer (DL), which facilitates reactants to reach the anode catalyst layer (CL). In this study, the impact of various DLs fabricated of readily accessible commercial materials on cell performance in passive DEFCs with different ethanol feed concentrations was examined with various in-situ characterization methods. The results demonstrate that the cell with a DL coated by the hydrophobic microporous layer (MPL) yielded the best performance of 0.887 mW·cm-2 at the optimal ethanol feed concentration of 5 M. In conclusion, the benefits of enhancing ethanol mass transfer to the anode CL would outweigh the drawbacks of preventing ethanol crossover to the cathode. [ABSTRACT FROM AUTHOR]

The enhancement of carbon-supported components is a crucial factor in augmenting the interplay between carbon-supported and metal-active components in the utilization of catalysts for direct ethanol fuel cells (DEFCs). Here, we propose a strategy for designing a catalyst by modifying candle soot (CS) and loading nickel onto ordered carbon soot. The present study aimed to investigate the effect of the Ni nanoparticles content on the electrocatalytic performance of Ni–CS, ultimately leading to the identification of a maximum composition. The presence of an excessive quantity of nickel particles leads to a decrease in the number of active sites within the material, resulting in sluggishness of the electron transfer pathway. The electrocatalyst composed of nickel and carbon support, with a nickel content of 20 wt%, has demonstrated a noteworthy current activity of 18.43 mA/cm2, which is three times that of the electrocatalyst with a higher nickel content of 25 wt%. For example, the 20 wt% Ni–CS electrocatalytic activity was found to be good, and it was approximately four times higher than that of 20 wt% Ni–CB (nickel–carbon black). Moreover, the chronoamperometry (CA) test demonstrated a reduction in current activity of merely 65.80% for a 20 wt% Ni–CS electrocatalyst, indicating electrochemical stability. In addition, this demonstrates the great potential of candle soot with Ni nanoparticles to be used as a catalyst in practical applications. [ABSTRACT FROM AUTHOR]

The inefficiency of Pt and Pd benchmark catalysts in achieving complete ethanol oxidation, coupled with their inherent susceptibility to poisoning, poses a significant obstacle to the advancement of direct ethanol fuel cells. In this study, the development of self‐supported and ultrathin RhCuBi trimetallenes, demonstrating exceptional performance in ethanol electrooxidation through segregation and interface engineering is presented. The distinctive RhBi‐rich crystalline/RhCu‐rich amorphous heterostructure of RhCuBi trimetallenes creates a wealth of highly active interfacial sites for the ethanol oxidation reaction (EOR). This results in an impressive 43.3% Faradaic efficiency for the C1 pathway and a peak mass activity of 1.11 A mgRh−1 at 0.68 V versus reversible hydrogen electrode. Moreover, RhCuBi trimetallenes retain 60% of their initial mass activity after 8.5 h of constant potential electrolysis, outperforming commercial Pd and Pt catalysts (<3%). In/ex situ infrared spectroscopy directly reveals the generated C1 products and the key CH3CO* intermediates for EOR on RhCuBi trimetallenes. Theoretical calculations confirm that the RhBi alloy, particularly the lattice‐stretched crystalline/amorphous interfacial sites, facilitates the adsorption/activation of ethanol and the dehydrogenation of CH3CO* toward the C1 pathway of EOR. This breakthrough offers promising prospects for enhancing the efficiency and stability of ethanol electrooxidation in fuel cell applications. [ABSTRACT FROM AUTHOR]

Palladium (Pd)-based catalysts have been extensively investigated in direct ethanol fuel cells (DEFCs) since the urgent energy and environmental problems. Rational design Pd-based catalyst with outstanding structure can optimize its electrocatalytic performance for ethanol oxidation reaction (EOR) catalyst. In this work, a facile strategy was proposed to prepare AuPd nanochain networks (NNWs) with core-shell structure by adjusting the reduction rate by slowly dropping the acidic reducing agent to the alkaline precursor solution system. The resulting catalysts exhibit a porous self-supporting structure with twisted features, exposing a large number of active sites. The optimized AuPd NNWs catalyst displays much-improved activity (3289.62 mA mg−1 Pd) and greatly enhanced electrocatalytic stability for EOR in comparison with that of commercial Pd/C catalysts. This enhanced activity can be attributed to the synergic effect of the Pd shell with the Au core as well as the twisted and self-supporting structure which can expose much more active sites and provide rich mass and electron transfer channels. [Display omitted] • A precise strategy was proposed to prepare heterogeneous AuPd core-shell nanochain networks using a one pot method. • The obtained AuPd core-shell nanochain networks consist of self-supported porous structure with rich active sites. • Electronic structure of Pd was optimized by the interaction of Au core with Pd shell. • The optimized AuPd core-shell nanochain networks display enhanced activity and stability toward EOR. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cell (DEFC) is promising source for mobile and portable applications, but the electrocatalysts are based on metal noble alloys or doping elements to minimize the incomplete ethanol oxidation and poisoning effect. While the main problem persists, this study describes the enhancement of ethanol oxidation reaction by adding graphene (G) to Vulcan XC-72R carbon black (C) metal support, with different C/G ratios. The Graphene was prepared from exfoliated graphite following by dried at ambient temperature. The 60 wt% graphene hybrid support enhances the current density at 5% cyclic voltammetry (CV) and 127% chronoamperometry (CA) higher than carbon pure support in acid electrolyte, whereas in alkaline, graphene (60 wt%) showed the highest electrochemical activity with an increase of current 82% (CV) and 130% (CA). Therefore, we demonstrated the enhancement of the catalyst electrochemical activity in both electrolytes through a simple synthesis method. The 40 wt% carbon and 60 wt% graphene hybrid support achieving higher performance in ethanol oxidation, evidencing a potential application in DEFC. [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 cells (DEFCs), which have been widely recognized as nontoxic and green energy conversion devices, show attractive application prospects for liquid hydrogen-carriers, due to the higher specific energy and lower toxicity of ethanol. Pt-based catalysts are widely used in DEFCs, while their poor poisoning resistance highlights the importance of composition and structure optimization. Herein, we synthesized a series of reduced graphene oxide supported ternary alloy AuxPt1−xCu3/rGO (x = 0-1) catalysts with excellent ethanol oxidation performance and a composition-dependent volcano plot trend of the ordering degree was observed and rationalized. The highest Pt-normalized mass activity of Au0.8Pt0.2Cu3/rGO is attributed to the optimized CO binding energy according to DFT calculations. This work not only provides an efficient EOR catalyst based on ordered alloys AuxPt1−xCu3 (x = 0-1), but also offers valuable insight into the role of a third metal in tuning the structure and function of alloys. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells (DEFCs) play an indispensable role in the cyclic utilization of carbon resources due to its high volumetric energy density, high efficiency, and environmental benign character. However, owing to the chemically stable carbon‐carbon (C─C) bond of ethanol, its incomplete electrooxidation at the anode severely inhibits the energy and power density output of DEFCs. The efficiency of C─C bond cleaving on the state‐of‐the‐art Pt or Pd catalysts is reported as low as 7.5%. Recently, tremendous efforts are devoted to this field, and some effective strategies are put forward to facilitate the cleavage of the C─C bond. It is the right time to summarize the major breakthroughs in ethanol electrooxidation reaction. In this review, some optimization strategies including constructing core–shell nanostructure with alloying effect, doping other metal atoms in Pt and Pd catalysts, engineering composite catalyst with interface synergism, introducing cascade catalytic sites, and so on, are systematically summarized. In addition, the catalytic mechanism as well as the correlations between the catalyst structure and catalytic efficiency are further discussed. Finally, the prevailing limitations and feasible improvement directions for ethanol electrooxidation are proposed. [ABSTRACT FROM AUTHOR]

Ternary nanoalloys used as electrochemical ethanol oxidation catalysts for direct ethanol fuel cells are confronted with poor stability issues under harsh acidic operating conditions. To address this issue, a carbon-supported quinary PtCuSnWNb high-entropy nanoalloy (denoted as PtCuSnWNb/C) was synthesized by using a polyol reduction method. Due to the unique high-entropy mixing states and strong catalyst–support interactions, PtCuSnWNb/C shows robust structural and compositional stability. [ABSTRACT FROM AUTHOR]

The preparation of electrocatalysts with high performance for the ethanol oxidation reaction is vital for the large-scale commercialization of direct ethanol fuel cells. Here, we successfully synthesized a high-performance electrocatalyst of a AuPd alloy with a decreased alloying degree via pulsed laser irradiation in liquids. As indicated by the experimental results, the photochemical effect-induced surficial deposition of Pd atoms, combined with the photothermal effect-induced interdiffusion of Au and Pd atoms, resulted in the formation of AuPd alloys with a decreased alloying degree. Structural characterization reveals that L-AuPd exhibits a lower degree of alloying compared to C-AuPd prepared via the conventional co-reduction method. This distinct structure endows L-AuPd with outstanding catalytic activity and stability in EOR, achieving mass and specific activities as high as 16.01 A mgPd−1 and 20.69 mA cm−2, 9.1 and 5.2 times than that of the commercial Pd/C respectively. Furthermore, L-AuPd retains 90.1% of its initial mass activity after 300 cycles. This work offers guidance for laser-assisted fabrication of efficient Pd-based catalysts in EOR. [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) provide a portable and environmentally friendly power source with high energy density. However, the slow kinetic of the ethanol oxidation reaction (EOR) has hindered the commercialization of DEFCs. Palladium (Pd)-based nanomaterials are the best promising catalysts for EOR due to the high catalytic activities and relatively abundant reserves. In this paper, we developed a simple and green way for the preparation of palladium hydride (PdH 0.43) and Au/PdH 0.43 heterostructures. Ethylene glycol (EG) provided the source of H atoms for the formation of PdH 0.43 in synthesis process. The as-synthesized PdH 0.43 and Au/PdH 0.43 nanocrystals were extremely stable under ambient conditions and annealing at 300 °C under Ar. Compared with PdH 0.43 and commercial Pd/C, Au/PdH 0.43 presented a higher mass activity of 2659 mA mg−1, a lower oxidation peak potential, and a higher catalytic stability for oxidizing ethanol. Remarkably, the improved catalytic performance might arise from the synergistically modulation of electronic structure, the enhanced resistance to poisoning products and the acceleration of electron transfer by the formation of palladium hydrides and abundant heterostructures of Au/PdH 0.43. This work provides a promising reference for the development of metal-hydride nanomaterials and heterostructures as efficient catalysts. • The PdH 0.43 and Au/PdH 0.43 were prepared with ethylene glycol as the H source. • The PdH 0.43 and Au/PdH 0.43 were extremely stable in the air over six months. • Au/PdH 0.43 can maintain the stability of structure even annealing at 300 °C in Ar. • Au/PdH 0.43 exhibited a higher performance toward EOR than PdH 0.43 and Pd/C. • The improved activities might arise from the doping of H and heterostructures. [ABSTRACT FROM AUTHOR]

In this study, palladium particles supported on carbon black (Vulcan XC-72) (Pd/C) and corncob biochar (Pd/CB800, Pd/CB900, and Pd/CB1000) were successfully synthesized using borohydride reduction. The biochar support was obtained from corncob waste via pyrolysis from 800 to 1000°C. Scanning electron microscopy with energy dispersive x-ray (SEM–EDX) revealed successful deposition of Pd metal particles on the carbon support materials. X-ray diffraction (XRD) analysis confirmed the crystalline structures of Pd, and the crystallite size was found to be smallest in Pd/CB900. The electrocatalytic activity of the Pd electrocatalyst composites towards ethanol oxidation reaction (EOR) in an alkaline medium was investigated using cyclic voltammetry (CV). CV analysis has shown that Pd/CB900 gave the least positive onset potential (Eonset = −0.587 ± 0.0065 V), highest electrochemically active surface area (EASA = 31.51 ± 2.24 m²·g−1), and highest anodic peak current density (If = 20.77 mA·cm−2) compared with Pd/CB800, Pd/CB1000, and Pd/C. Furthermore, the Tafel plot and chronoamperometry have shown that Pd/CB900 exhibited faster kinetics (Tafel slope = 297.6 ± 4.62 mV·dec−1) and durability (% current retention = 50.64 ± 2.99%) than Pd/C towards EOR in an alkaline medium. This study highlights the simple and straightforward synthesis of the anode electrocatalyst material for direct ethanol fuel cell application. [ABSTRACT FROM AUTHOR]

Effective and stable catalysts toward ethanol oxidation reaction (EOR) is very important for the application of direct ethanol fuel cells (DEFCs). This research reports a facile synthesis of Ni/sepiolite (Ni/SEP) catalyst through incipient wetness impregnation method, which has large amount of active sites and excellent electrochemical activity toward EOR. Through scanning electron microscope with energy dispersive spectroscopy (SEM-EDS), nickel was found to distribute evenly on the fiber structure of sepiolite through ion exchange with the element magnesium without altering the main structure. With a geometric surface area of 0.07 cm2, Ni/SEP had a larger electrochemical surface area 0.44 m2 g−1, lower onset potential of 0.28 V (vs. SCE), higher peak current density (258.5 mA cm−2), and smaller Tafel slope (20 mV dec−1), indicating a superior electrochemical activity toward EOR. Within the experimental conditions, it was observed to be a diffusion-controlled process based on the linear relationship between peak current and root of scan rates, and the reaction could be accelerated by the increase of both C2H5OH and KOH concentrations. Through the study of cyclic voltammetry as well as calculation of apparent activation energy, an electrolytic-chemical (EC) reaction mechanism was suggested with high valence Ni species as the electron transfer carrier. [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.

The development of highly active and cost‐effective electrocatalysts for the ethanol oxidation reaction (EOR) is imperative for the prospective application of direct ethanol fuel cells (DEFCs). In this study, we successfully synthesized porous octahedral nanoarchitectures comprising Pd, Rh, and Pt, through a straightforward one‐step co‐reduction aided by additional Ag precursors and other surface capping agents. The in‐situ galvanic replacement played a pivotal role in shaping hollow structures within the prepared PdRhPt porous octahedra, designated as PdRhPt‐POct. By strategically employing both composition and structure engineering, PdRhPt‐POct exhibited remarkably enhanced activity and stability toward EOR. Specifically, the mass activity of PdRhPt‐POct, reaching 8.11 A mg−1Pd+Pt, surpassed that of the majority of state‐of‐the‐art EOR electrocatalysts, owing to increased efficiency in C−C bond breaking and enhanced anti‐poisoning properties. This work introduces new prospects for designing and producing unique hollow‐structured multi‐metal nanocrystals as high‐performance EOR catalysts. [ABSTRACT FROM AUTHOR]

Tin dioxide-modified Pt electrodes with different coverages ( θ SnO 2 ) were prepared by potentiostatically depositing tin on a Pt electrode in 0.1 M H2SO4 solutions containing various concentrations of SnCl2, followed by oxidizing in air. The θ SnO 2 was controlled by the SnCl2 concentration. The CO-stripping voltammogram of the Pt/SnO2 electrode with θ SnO 2 = 0.61 (Pt/SnO2(0.61)) exhibited two peaks, a prepeak due to the oxidation of adsorbed CO at Pt sites adjacent to SnO2 and a main peak due to that at Pt sites far from SnO2. In the kinetic analysis of both peaks using CO-stripping voltammograms at various sweep rates, the rate-determining steps for the prepeak and main peak were the coupling of adsorbed CO on Pt with OH on SnO2 surface by bifunctional effect and the dissociatively adsorption reaction of water to adsorbed OH on Pt, similar to the Pt electrode, respectively. In the linear sweep voltammograms of Pt/SnO2 electrodes in a (0.1 M HClO4 + 1 M ethanol) solution, the current for ethanol oxidation reaction (EOR) was the highest for θ SnO 2 = 0.61. The analysis of EOR products at different potentials for the Pt/SnO2(0.61) electrode by in situ infrared reflectance-absorption spectroscopy exhibited the Pt/SnO2(0.61) electrode facilitated acetic acid production. Moreover, rhodium was electrochemically deposited on the Pt sites adjacent to SnO2 using the limited CO-stripping technique. The area-controlled Rh deposition did not change the rate-determining steps of both peaks, but it not only enhanced EOR activity, but also decreased acetic acid selectivity and increased CO2 selectivity. [ABSTRACT FROM AUTHOR]

In this study, an iridium-oxide-layer-deposited Pt surface (IrOx–Pt) was explored as a catalyst for the ethanol oxidation reaction (EtOR) in an alkaline medium. To fabricate the catalyst, the cleaned Pt surface was scanned from 0 V to +1 V vs. Ag/AgCl (sat. KCl) in an Ir2O3·xH2O colloidal suspension for 10 continuous cycles. The cyclic voltammogram recorded in the 0.1 M NaOH solution corroborated the presence of IrOx as it showed the appearance of a distinct redox pair on the Pt surface, with Epa at −0.31 V and Epc at −0.27 V. Energy-dispersive mapping verified the uniform deposition of IrOx on Pt, and X-ray photoelectron spectroscopy showed that IrOx contained both IrIII and IrIV species. The results of the cyclic voltammetry analysis indicated that the activity of the pure Pt catalyst towards the EtOR was approximately 1.3 times greater than that of IrOx–Pt. However, the CO tolerance of the Pt catalyst was roughly 3.5 times lower than that of IrOx–Pt. The results of the stability test indicated that the current density associated with EtOR on the IrOx–Pt electrode experienced a decrease of approximately 18% with a standard deviation of 1.15% after 500 consecutive cycles. In contrast, the Pt electrode exhibited a decrease in activity of nearly 50% with a standard deviation of 1.53% under similar experimental conditions. The study of scan rate dependent voltammograms revealed that the electrode reaction was limited by mass transfer. [ABSTRACT FROM AUTHOR]

BACKGROUND: Direct ethanol fuel cells (DEFC) need fillers to mitigate the issue of ethanol crossing over from the anode to the cathode, which lowers performance. Therefore, this study developed calcium carbonate (CaCO3) from chicken eggshells as a filler in a Nafion composite membrane for DEFC. Three cluster models of CaCO3 filler were developed, namely (CaCO3)2, (CaCO3)3, and (CaCO3)4, to form the Nafion composite membranes. The properties of composite membranes, such as proton conductivity, ethanol permeability, and selectivity, were studied using the molecular dynamics method. In addition, the three main factors influencing the composite membranes' properties were analyzed in this study; these were cluster size of CaCO3, mass loading of the filler, and ethanol concentration. RESULTS: The results show that filler has reduced proton conductivity and ethanol permeability in the DEFC application compared to the Nafion membrane. However, the selectivity is used as a trade‐off between ion conductivity and ethanol permeability in the composite membrane, thus requiring a suitable size structure and mass loading to balance the high ion conductivity rate and reduce the ethanol permeability rate. The composite membrane C‐(CaCO3)4, which has a large cluster size in this study, shows that it is necessary to restrict ethanol permeability at a high ethanol concentration of 5 mol L−1. However, the structure size in cluster B – (CaCO3)3 – can reduce ethanol permeability but requires high mass loading by 5 wt%. Analysis of variance showed significant values for ion conductivity, ethanol permeability, and selectivity responses. CONCLUSION: CaCO3 successfully reduced ethanol crossover in DEFC, with all three composite membranes being suitable for use at low ethanol concentrations. However, specific size structure and mass loading are required to overcome ethanol crossover at high ethanol concentration. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

This Topic on the "Application of Graphene-Based Materials", which consists of a total of twenty-six articles, including two review articles, written by research groups of experts in the field, considers the most recent research and trends on the synthesis and characterization of graphene-based materials, including nanohybrids, intended for a vast array of high-demanding technological applications, namely batteries/fuel cells, aerogels, laser technology, sensors, electronic/magnetic devices, catalysts, etc. 36432228 11 Rodríguez-Pastor I., López-Pérez A., Romero-Sánchez M.D., Pérez J.M., Fernández I., Martin-Gullon I. Effective Method for a Graphene Oxide with Impressive Selectivity in Carboxyl Groups. Taking advantage of the particular structure of aerogels and, hence, possible highly efficient adsorption capabilities, Jin and co-workers [[9]] developed bionanocomposite aerogels containing graphene oxide for the removal of dyes, specifically methylene blue, from wastewater. Interestingly, they were able to create a gradient-like open-cell graphene aerogel with an extremely high microwave absorption value of 62.6 dB only using 0.53 wt% graphene, which they explained based on a multiple reflection effect due to the open-cell structure and well-matched impedance due to its gradient structure. [Extracted from the article]

Direct Ethanol Fuel Cells (DEFCs) are important clean energy conversion systems which can reach high energy densities using inexpensive and non-toxic fuels. One of the main obstacles to using DEFC systems is the high cost of platinum or platinum-alloy electrodes traditionally used in these systems. However, other less expensive co-catalysts, e.g., transition metal complexes, can be used to partially replace platinum or platinum-alloys in Pt-based electro-catalysts. The aim of this study is to describe and analyze the use of a new uranyl salen-type complex as co-catalyst in ethanol electro-oxidation. To this end, the structural and spectroscopic properties of the co-catalyst in question was investigated by single-crystal X-ray diffraction, DFT, elemental analysis (CHN), FTIR, UV-Vis, and 1H and 13C NMR. Cyclic voltammetry indicated a quasi-reversible redox pair at 0.97/0.69 V (E1/2 = 0.83 V) along with an anodic process at 1.14 V, both associated to the phenolate/phenoxyl radical couple. Six PtSn-based catalysts were produced by varying the PtSn:uranyl complex molar ratio. The ethanol oxidation reaction was investigated in acidic media via cyclic voltammetry and chronoamperometry. Direct scanning of the samples indicated that the peak-current density for the 6 : 1 PtSn/C : [UO2(3-OMe-c-salcn)H2O] catalyst was higher than that for other catalyst ratios. Moreover, as compared to the pure PtSn catalyst, 6 : 1 PtSn/C : [UO2(3-OMe-c-salcn)H2O] exhibited better catalytic activity in ethanol electro-oxidation reaction (EOR); it decreased the onset potential during ethanol oxidation. In addition, this catalyst exhibited peak-current densities about 2.3 times that of PtSn/C. pH affected the catalytic system performance, which decreased as pH increased (maximum efficiency at pH 0.3). Ethanol oxidation catalyzed by 6 : 1 PtSn/C : [UO2(3-OMe-c-salcn)H2O] was also investigated using cyclic voltammetry and chronoamperometry at different ethanol concentrations, indicating that the EOR peak increased as ethanol concentration increased. [ABSTRACT FROM AUTHOR]

Pt-Sn/C has been widely reported as an anode catalyst in direct ethanol fuel cell (DEFC). However, this bimetallic catalyst often results in the production of a four-electron reaction product (acetate) instead of 12 electrons required for complete ethanol oxidation. In this work, a surfactant-free bromide anion exchange (BAE) method was used for the first time to prepare rare-earth (La, Ce, Pr, and Eu) modified Pt-Sn electrocatalysts for promoting the C-C bond cleavage. Among the synthesized nanomaterials, Pt-Sn-Ce/C exhibited the highest current density and good stability in alkaline medium. X-ray photoelectron spectroscopy (XPS) was used to analyze the surface properties of the synthesized materials and correlate them with electrochemical characterizations to enhance their activity towards ethanol oxidation reaction (EOR). The in situ Fourier transform infrared (FTIR) spectroscopy investigations provided evidence of similar EOR pathways for Pt-Sn and rare-earth modified bimetallic anodes. The presence of the cocatalysts promoted higher current density during the EOR, especially for Pt-Sn-Ce/C. [ABSTRACT FROM AUTHOR]

Here, we report the successful synthesis of ZnO–Cu nanocomposites through a two-step modified polyol route: First, the Cu precursor was microwave heated in ethylene glycol, water, and NaOH solution. Subsequently, ZnO was formed by adding a mixture containing ZnCl2. We evaluated the physical and chemical characteristics of the obtained nanostructures by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and Raman spectroscopy. The activity for the ethanol electrooxidation reaction (EOR) was determined by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements. Based on the XRD results, we concluded that the material forms a ZnO-Cu composite with a crystallite size of 11.9 nm and 19 nm for the ZnO and Cu species, respectively. Raman results suggest the presence of oxygen deficiencies in the ZnO-Cu nanocomposite, a relevant finding considering that this phenomenon improves the electrical conductivity in ZnO-based materials. CV and CA indicated that incorporating Cu into the ZnO structure increases the current density of the EOR in alkaline media. EIS demonstrated that the improved catalytic activity is due to the lower charge transfer resistance in the ZnO–Cu, mainly attributed to the synergic effect between the ZnO and the Cu species. The current research reveals the potential of the two-step microwave-assisted polyol synthesis process to synthesize nanocomposites in a short heating time. This simple, scalable, and effective approach helps develop ZnO–Cu nanostructures or other ZnO–based electrocatalysts for efficient ethanol electrooxidation. [ABSTRACT FROM AUTHOR]

In passive direct ethanol fuel cells (DEFCs), the micro-porous layer (MPL) is a vital component of the membrane electrode assembly (MEA), facilitating gas-liquid mass transport and improving electronic conductivity. The conducted study involved preparing various carbon materials for the cathode MPL, including Ketjen Black (KB), activated carbon (AC) from Durian shells, and a 15% weight mixture of AC and KB (AC15%). Characterization of the activated carbon was carried out using nitrogen adsorption-desorption isotherm analysis. Additionally, various electrochemical techniques, including cell polarization, electrochemical impedance spectroscopy (EIS), anode half-cell polarization, and anode EIS, were conducted to examine the effects of the cathode MPLs on cell performance. The results indicated that the cell with the conventional KB cathode MPL displayed the highest performance, whereas the AC15% and AC cathode MPLs showed relatively lower performances, respectively. The AC cathode MPL in the cell encountered challenges, such as decreased pore volume, increased micropores, and a hydrophobic electrode nature, leading to reduced gas transport resulting in poor cell performance. In contrast, the AC15% cathode MPL, which combined AC and KB in the electrode, achieved an appropriate micropore and mesopore balance. However, performance did not improve due to a heterogeneous contact surface between the cathode catalyst layer and the cathode MPL, resulting in higher ohmic resistance. Incorporating biomass-based materials into the electrode presents an interesting possibility due to the utilization of cheap and readily available precursors, as well as the ability to tailor morphology. Conducting a systematic study of durian shell activated carbons would reveal improved properties of the carbon material suitable for implementing in the MPL of passive DEFCs. [ABSTRACT FROM AUTHOR]

The crucial issue restricting the application of direct ethanol fuel cells (DEFCs) is the incomplete and sluggish electrooxidation of ethanol due to the chemically stable C−C bond thereof. Herein, a unique ethylene‐mediated pathway with a 100 % C1‐selectivity for ethanol oxidation reaction (EOR) is proposed for the first time based on a well‐structured Pt/Al2O3@TiAl catalyst with cascade active sites. The electrochemical in situ Fourier transform infrared spectroscopy (FTIR) and differential electrochemical mass spectrometry (DEMS) analysis disclose that ethanol is primarily dehydrated on the surface of Al2O3@TiAl and the derived ethylene is further oxidized completely on nanostructured Pt. X‐ray absorption and density functional theory (DFT) studies disclose the Al component doped in Pt nanocrystals can promote the EOR kinetics by lowering the reaction energy barriers and eliminating the poisonous species. Strikingly, Pt/Al2O3@TiAl exhibits a specific activity of 3.83 mA cm−2Pt, 7.4 times higher than that of commercial Pt/C and superior long‐term durability. [ABSTRACT FROM AUTHOR]

Energy conversion devices based on liquid fuels have gained considerable attention in recent times to meet the increasing global demand for energy. In this work, graphitic carbon nitride (gCN) nanosheets have been synthesized by pyrolysis of urea and Co has been decorated in different molar ratios over its surface by the solution phase method. The prepared catalysts have been utilized for photo electrooxidation of ethanol, an anodic half-cell reaction in direct ethanol fuel cells. Electrochemical studies show that the catalyst containing 3 mol % of Co shows the best activity with a peak current density of 6.91 mA/cm2 obtained at a peak potential of 0.28 V with maximum current density of 40 mA/cm2. The effect of light on the catalytic activity has also been studied. On illuminating the surface of the electrode with light, an increment of 85% in current density is observed which indicates higher charge transfer that enhanced the photoactivity of the catalyst. This study confirms the practical applicability of the non-expensive carbonaceous material Co–C 3 N 4 utilization as a photoanode in future energy systems. Application of cobalt decorated graphitic nitride for photo-assisted ethanol oxidation in alkaline medium. [Display omitted] • Mechanistic insight of stabilization of graphitic carbon nitride (gCN) nanosheets. • Surface decoration with different concentration of Co on gCN at low temperature. • Electrochemical properties of samples with various amount of Co were investigated. • The catalyst containing 3 mol% Co shows best activity for ethanol oxidation with low impedance. • Photocurrent measurements shows an enhancement of 85% in the current density. [ABSTRACT FROM AUTHOR]

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]

Pd electrocatalysts supported on carbon nanotubes (CNTs) and carbon nanofibres (CNFs) and their combination thereof were evaluated for their effective ethanol oxidation reaction. The electrocatalysts (namely Pd/CNT, Pd/CNF and Pd/CNT-CNF) were synthesized and characterized using BET, TEM, XRD, TGA and Raman spectroscopy techniques. Electrochemical characterization using cyclic voltammetry in the presence of [Fe(CN)6]3/−4 redox probe showed that the electrocatalysts exhibited excellent current response on glassy carbon electrode in the order of Pd/CNT > Pd/CNF > Pd/CNT-CNF. In contrast, in alkaline ethanolic solution, the order of oxidative current response was Pd/CNF < Pd/CNT < Pd/CNT-CNF, implying better electrocatalytic activity for the ternary electrocatalysts. The superiority of Pd/CNT-CNF over other electrocatalysts was further revealed using chronoamperometry (current density: 51.52, 13.31 and 11.25 mA cm−2 for Pd/CNT-CNT, Pd/CNF and Pd/CNT, respectively). Furthermore, the ternary electrocatalysts demonstrated excellent stability after 1500 cycles, making it attractive as a durable electrode for fuel cell technology development. [ABSTRACT FROM AUTHOR]

In this work, to prepare nanostructured and porous Fe/Pd–Fe bimetallic catalysts, the iron coating is applied firstly onto the copper substrate by the electrochemical deposition method. Subsequently, iron-zinc alloy coating is deposited on the underlayer iron. Eventually, by immersing this alloy coating in an alkaline solution containing palladium ions, the palladium will replace the zinc, resulting in porous Fe/Pd–Fe catalysts. The X-ray diffraction (XRD) technique was used for the characterization of the physical properties of the as-prepared electrocatalysts. Their electrocatalytic activity was studied by electrochemical methods such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The XRD results showed that the zinc element was the main component of the Fe/Zn-Fe alloy and was replaced by palladium as a result of leaching-galvanic replacement. The electrochemical investigations showed that a new porous Fe/Pd-Fe bimetallic catalyst had higher electro-catalytic activity and stability than pure Pd and Fe electrodes for ethanol electro-oxidation in alkaline media. The superiority of the Fe/Pd–Fe catalyst is related to the high surface area and a synergistic effect between Fe and Pd in Fe/Pd–Fe catalysts. Therefore, the nanostructured Fe/Pd–Fe catalysts can be proposed as potential anode materials for alkaline ethanol fuel cells. A new porous Fe/Pd–Fe bimetallic catalyst shows higher electro-catalytic activity and stability than pure Pd and Fe electrodes for ethanol electro-oxidation in alkaline media. The superiority of the Fe/Pd–Fe catalyst is related to the high electrochemical surface area and a synergistic effect between Fe and Pd in Fe/Pd–Fe catalysts [ABSTRACT FROM AUTHOR]

A probable catalytic mechanism of EOR and ORR on PtPdCu/CNTs was summarized, where: (i) The highly dispersed ultrafine ternary alloy nanoparticles give rise to an excellent bifunctional catalytic activity. (ii) The introduction of Pd/Cu into Pt lowers the d-band center of Pt, leading to the accelerated desorption of carbonaceous species. (iii) The Pd/Cu dopant favors the generation of hydroxyl radicals, resulting in facilitated removal of intermediates on Pt sites. (iv) The introduction of the carboxyl (2%) modified CNT is beneficial for effectively anchoring the metal nanoparticles, promoting the mass transfer and regulating the electron transfer. [Display omitted] • PtPdCu/CNTs was fabricated via a surfactant-free one-pot solvothermal synthesis. • PtPdCu nanoparticles at ∼5 nm can be homogenously dispersed on CNTs. • PtPdCu/CNTs exhibit high activity and good stability for EOR and ORR. • XPS and DFT studies reveal the lowered d band center of Pt upon Pd-Cu alloying. • DFT calculations implies a favored C1-path on PtPdCu/CNTs during EOR. Bifunctional catalysts for ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR) with high noble-metal utilization are highly beneficial to direct ethanol fuel cells (DEFCs). This study developed a ternary bifunctional catalyst composed of ultrafine PtPdCu alloy nanoparticles and carbon nanotubes (CNTs) support through a facile surfactant-free solvothermal route. The carboxyl terminal groups on CNTs ensure the confined growth of PtPdCu alloys (∼5 nm) and suppress Ostwald ripening of metallic active sites during electrochemical cycling. Consequently, PtPdCu/CNTs exhibits high mass activity (1.95 A mg−1) and specific activity (4.08 mA cm−2) toward EOR, which are 7.8 and 8.9 times higher, respectively, than those of commercial Pt/C. Furthermore, PtPdCu/CNTs displays superior stability toward EOR compared with its bimetallic counterparts (PtPd/CNTs and PtCu/CNTs). In addition, PtPdCu/CNTs exhibits the highest half-wave potential of 0.888 V among all electrocatalysts, indicating high ORR activity. Density functional theory calculations reveal that Pd and Cu mediate the electronic structure of Pt, leading to enhanced catalytic activity of PtPdCu/CNTs. The excellent catalytic property of PtPdCu/CNTs can also be attributed to the bifunctional effects of Pd/Cu and the interaction between metal and the carbon support. The proposed material is a contribution to the family of efficient ternary-alloy electrocatalysts for fuel cells. [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]

In this work, the synergism between the nano nickel particles and its carbon xerogel support, CX, together with their graphite substrate, G, leads to an efficient Nickel/CX/G electrode for electrocatalysis of ethanol oxidation reaction, EOR. The preparation conditions are optimized. The optimum electrode is made of 6 % weight of Ni doped in CX matrix and drop‐casted on a graphite surface, Ni‐6/CX/G. The catalyst structure and morphology are investigated using XRD, SEM, TEM and FTIR techniques. The electrochemical activity towards EOR is tested in 1 M NaOH+1 M Ethanol solutions by cyclic voltammetry combined with a rotating ring disk electrode. The optimum electrode shows an oxidation peak current density value of 5925 A.gNi-1 ${{\rm A}.{{\rm g}}_{{\rm N}{\rm i}}^{-1}}$ and considerable stability. This electrode may serve as a good candidate for the anode in the Direct Alkaline Ethanol Fuel Cell, DAEFC. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells (DEFCs) technology as a promising clean-energy, is obstructed by unsatisfactory activity of ethanol oxidation reaction (EOR) nanocatalysts. Traditional shape-controllers usually lead to regular nanoparticles. Three-dimensional dendrimers, like hyperbranched polyamide (HBPA), however, have superiorities to form irregular morphologies, due to their multitudinous terminal functional groups and irregular interior cavities. Considering the lack of researches, herein, a novel HBPA was utilized to facilely and controllably synthesize irregular gravel-like PtPd nanoparticles (g-PtPd-NPs) with rich active sites. The synthetic mechanism was studied by both experiments and density functional theory calculations. N atoms of HBPA were proven essential. In EOR tests, the activity of g-PtPd-NPs was 2.05-fold of commercial Pt/C, and higher than PtPd catalysts of control sets and reports. The durability was excellent, too. This study is promotive for DEFCs into practice, and may enlighten more nanomaterials' synthesis. [Display omitted] • Irregular gravel-like PtPd nanoparticles were prepared facilely and controllably. • A novel 3D hyperbranched polyamide was adopted for shape-controlling. • The synthetic mechanism was studied by combining experiments and DFT calculations. • The product exhibited excellent catalytic properties in ethanol oxidation reaction. [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]

Direct ethanol fuel cells (DEFCs) have received increasing attention as one of the most promising energy conversion devices. However, developing catalysts with high activity, long durability and strong anti-poisoning ability for ethanol oxidation is still challenging. Here, using Pd nanosheets as sacrificial templates, we have successfully synthesized PdPtBi networked nanowires (NWs) to improve the activity and stability for ethanol oxidation reaction (EOR) due to the addition of Bi. Density functional theory (DFT) calculations demonstrated the downshift of d-band center of Pd, which is beneficial to suppress CO poisoning and boost reaction kinetics for EOR. Impressively, the PdPtBi networked NWs exhibited the highest activity ( 11.08 A ⋅ mg Pd + Pt − 1 and 92.52 mA·cm−2) with an enhancement of 4.4 and 17.5 times relative to those of Pd/C, respectively and best stability with a 47.2% left versus only a 5.8% left for Pd/C of mass activity after 3,600 s towards EOR. This work deepens the understanding of controllable preparation of networked NWs and provides an effective strategy to design advanced catalysts with high activity and stability. [ABSTRACT FROM AUTHOR]

The synthesis of Pt−Rh alloy nanowires (NWs) using straightforward methodologies remains a challenge. Here, carbon‐supported Pt and Pt−Rh nanowire catalysts were synthesised by chemical reduction at room temperature, without using surfactants or templates. The method of synthesis used yielded Pt/C NWs and a mixture of nanowires with some nanoparticles for the Pt−Rh/C catalysts (characterised using XRD, TEM, EDX, XPS, and XAS). The nanoparticles form due to differences in the surface energy and atomic radius between Pt and Rh. The binary NWs are found to be more active towards ethanol oxidation than the commercial Pt/C reference catalyst. Additionally, the Pt−Rh/C NW catalyst displays a specific activity 2.5‐fold higher than the Pt/C NWs and Pt/C reference catalysts after 15 min of chronoamperometric tests (at 0.5 V vs RHE). Thus, the synthesised carbon‐supported Pt NWs and Pt−Rh nanowires‐nanoparticles are promising alternatives for direct ethanol fuel cell anodes. [ABSTRACT FROM AUTHOR]

Rational design and synthesis of high-performance electrocatalysts for ethanol oxidation reaction (EOR) is crucial to large-scale commercialization of direct ethanol fuel cells, but it is still an incredible challenge. Herein, a unique Pd metallene/Ti3C2Tx MXene (Pdene/Ti3C2Tx)-supported electrocatalyst is constructed via an in-situ growth approach for high-efficiency EOR. The resulting Pdene/Ti3C2Tx catalyst achieves an ultrahigh mass activity of 7.47 A mgPd-1 under alkaline condition, as well as high tolerance to CO poisoning. In situ attenuated total reflection-infrared spectroscopy studies combined with density functional theory calculations reveal that the excellent EOR activity of Pdene/Ti3C2Tx catalyst is attributed to the unique and stable interfaces which reduce the reaction energy barrier of *CH3CO intermediate oxidation and facilitate oxidative removal of CO poisonous species by increasing the Pd-OH binding strength. [ABSTRACT FROM AUTHOR]