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Nickel foam has been widely used as an electrode supporting material for alkaline direct ethanol fuel cells (ADEFC). However, the smooth skeleton surface of pristine nickel foam results in low specific surface area, such that a high-load catalyst is required to deal with ethanol oxidation, which limits its application as a catalyst support. Therefore, efforts to enhance the roughness of skeleton surface and reduce the catalyst loading have been intensively made. One of the conventional approaches is hydrochloric acid (HCl) etching method, which can remove the inert layer but does not change the surface roughness. In this paper, a mixed acids treated nickel foam anode with low Pd loading (0.35 mg cm−2) is prepared by simply soaking for three times for ADEFC performance testing. The peak power density reaches 30 mW cm−2, which is double the performance of the HCl treated anode. The performance improvement is attributed to the micro-holes produced by mixed acids etching, which enhance the roughness of skeleton and improve electrochemical active surface area (ECSA) of the catalyst. This work opens a new platform for in-depth exploration on metal foam electrodes in fuel cells. [Display omitted] • Low duration (15 s) etching of mixed acids enriches the surface roughness of the nickel foam. • The palladium/nickel foam anode is prepared by simply soaking for three times. • This novel anode shows 30 mW cm−2 of peak power density, even with low Pd loading at 0.35 mg cm−2. [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]

The poor long-term stability of anodic catalysts is one of the important factors that hinder the commercial application of direct ethanol fuel cells. The main reason is that toxic intermediates (such as CO) produced in the process of ethanol oxidation are easy to cover the active site, resulting in the catalyst being poisoned and deactivated in a short time. In this work, the prepared catalysts by the co-reduction method use didecyldimethylammonium chloride (DODAC) as the structure directing agent. The PdAg microporous alloy nanospheres in situ growth can effectively separate the GO sheets and slow down the stacking by self-intercalation effect. And introduced Ag into Pd lattice effectively modify the electronic structure of Pd and form OH− at a lower potential, which is helpful the oxidation of CO and weakens the poisoning effect of CO, improving the catalytic performance. After 20,000 s stability test, the residual current density value of mPd 1 Ag 1 @FrGO is 659 mA mg Pd - 1 , which is 20 times of Pd/C (JM). After 4 cycles of 20,000 s i-t test, its current density only dropped by 18.2%. In addition, the catalyst mPd 1 Ag 1 @FrGO has good regeneration ability. After 6 cycles of regeneration, the residual current density value is 878.1 mA mg Pd - 1 . [Display omitted] • The PdAg microporous alloy nanospheres can slow down the stacking of GO sheets. • The residual current density of Pd 1 Ag 1 /FrGO after 20,000 s is 20 times of Pd/C (JM). • mPdAg@FrGO with porous structure has good stability and regeneration ability. [ABSTRACT FROM AUTHOR]

Design of direct ethanol fuel cell (DEFC) plays a key role in its viability. A novel tubular DEFC is proposed to reconstruct the conventional structure, and tubular cathode is prepared by gel injection molding with Mesocarbon microbeads (MCMB), graphite and NH 4 Cl with different contents as raw materials. Moreover, simulation on the mass transfer and electrochemical performance of DEFC with a wider range of cathode porosity is carried out. Experiment results indicates that the support has higher porosity and strength when the graphite doping and NH 4 Cl is 40% and 2%–10%, respectively. Furthermore, superior performance of cathode and DEFC electrical performance are perceived due to larger porosity, especially when the porosity is 0.5. Moreover, in the simulation the results also show that porosity of cathode diffusion layer (CCL) has a significant effect on the oxygen mass transfer and removal of liquid water. Larger porosity means better electrical performance and delivers more power, which is more obvious at 0.2–0.6. It is proved that when the porosity is about 0.5, comprehensive performance of tubular DEFC is better than other models. • A novel t-DEFC of cathode mainly prepared by MCMB, graphite and NH 4 Cl is developed. • 40% graphite and 0–10% NH 4 Cl led to larger porosity and better electrical performance, especially the porosity is 0.5. • Wider cathode porosity effects on mass transfer and DEFC performance is studied. • The maximum power density could reach about 21.96 mW/cm2 when the porosity is 0.5. [ABSTRACT FROM AUTHOR]

Palladium nanoparticles (Pd NPs) were successfully electrodeposited on a reduced graphene oxide/poly(melem-formaldehyde) nanocomposite (rGO/PMF) NC as a catalyst for ethanol electrooxidation in alkaline media; melem was used as a nitrogen-rich source in the substrate structure for the first time. The specific surface area and average pore diameter of (rGO/PMF) NC were 481.61 m2 gr−1 and 10.23 nm, respectively. High nitrogen doping and structural defects improved the dispersion and anchoring of Pd NPs on (rGO/PMF) NC. The onset potential (E onset) of Pd/(rGO/PMF) NC was shifted negatively to 110 mV, in comparison to Pd/rGO. Also, the current density and electrochemical active surface area (EASA) of Pd/(rGO/PMF) NC were enhanced to 44 mA cm−2 and 67.58 m2 gr−1, respectively, as compared to Pd/rGO. Furthermore, the stability of Pd/(rGO/PMF)NC was indicated against ethanol oxidation intermediates during 7000 s. This work also produced a superior graphene-based material for direct ethanol fuel cell anode catalysts applications. [Display omitted] • The Pd/(rGO/PMF) NC catalyst was fabricated for the first time. • Melem was used as a nitrogen-rich source in the (rGO/PMF) NC substrate structure. • Pd/(rGO/PMF) NC has a high surface area and a porous nanostructure. • Pd/(rGO/PMF) NC has a promising activity and stability for EOR. [ABSTRACT FROM AUTHOR]

To facilitate the electrocatalytic behavior of Direct Ethanol Fuel Cells (DEFCs), a sequence of bimetallic Pd x Cu y /Ni 2 P-C catalysts are synthesized via the microwave-assisted ethylene glycol reduction method. The results indicate that our designed Pd 2 Cu/Ni 2 P-C(1:1) catalyst owns high activity (3974.08 mA mg−1 Pd), 8.3 times higher than the commercial Pd/C. The durability and the CO tolerance of the corresponding catalysts are also investigated by chronoamperometry (CA) and CO stripping measurements, implying Pd 2 Cu/Ni 2 P-C(1:1) shows good durability and the anti-CO poisoning ability for EOR in alkaline media. The electrochemical impedance spectra (EIS) analysis reveals lower charge transfer resistance for Pd 2 Cu/Ni 2 P-C(1:1). Combined with the results of XRD, HRTEM, XPS and electrochemical measurements, we found that the good electrocatalytic activity, CO tolerance and long-term durability of Pd 2 Cu/Ni 2 P-C(1:1) may be provided by the electronic and strain effect among Pd, Cu and Ni 2 P, which will bring the downshift in the d-band center of catalysts and the weakened adsorption of intermediates. [Display omitted] • Pd 2 Cu/Ni 2 P-C exhibits high mass activity for EOR in alkaline media. • Pd 2 Cu/Ni 2 P-C shows good stability and the anti-CO poisoning ability. • The introduction of Ni 2 P and appropriate Cu can enhance EOR efficiency. • Enhanced activity is ascribed to the electronic interaction and lattice compression. [ABSTRACT FROM AUTHOR]

[Display omitted] • Iron nitrate enhances adsorption capacity of cotton, activates carbon pores and develop magnetic specie in carbon. • A green method of simultaneous carbonization, activation and magnetization. • Magnetism enhances ethanol oxidation in 5.6 times compared to Pd/AlfaAesar catalyst. • Better dispersion of Pd nanoparticles due to high micro porosity of cotton carbon. Activate carbon (AC) demand has increased worldwide, with application in adsorption, heterogeneous catalysis, and most recently as electrocatalyst support. However, while AC production from agro-industrial waste are widely researched, textile waste is neglected as raw material. In this study, cotton fabric was first applied as textile dye adsorbent after iron impregnation, which enhanced the adsorption capacity. The dye adsorbed fabric was than sequentially pyrolyzed at 800 °C for 2 h under N 2 atmosphere, producing a magnetic mesoporous activated carbon (MAC) of 472 m2 g-1 BET surface area with 82% micropores and magnetization saturation of 34.2 emu g-1 deriving from encapsulated metallic αFe. This new simple and fast one-step carbonization, activation and iron incorporation method, has very low chemicals consumption and waste generation compared to the traditionally applied ones. The so produced MAC was loaded with 20 % Pd and tested for electrocatalyst properties: high density current for ethanol oxidation of 549 mA mg-1Pd, 1.37 times higher than using commercial Pd catalyst, lower onset potential of -0.48 V vs NHE. Application of the electrocatalyst for direct ethanol fuel cell achieved a high energy production of 27 mW cm-2 at 353 K. [ABSTRACT FROM AUTHOR]

Ethanol is considered an alternative fuel to power fuel cells, especially due to its ease of transport and storage and renewable production on a large scale. However, its use in direct ethanol fuel cells (DEFC) is still limited by incomplete electro-oxidation and slow reaction kinetics. Modeling approaches have focused on investigating different reaction mechanisms, but so far, no formal analysis of model parameter sensitivity has been conducted. This work modeled and identified sensitive parameters for different types of Pt–Sn catalysts previously prepared by our research group that displayed good performance in the 5–15 mW/cm2 range (relative to a performance of 12 mW/cm2 achieved by a commercial ETEK catalyst). Analyses to study the effect of these parameters on coverage fraction distribution, reaction rates and possible correlations were also performed. The model was developed based on Butler–Volmer kinetics and on a reaction mechanism previously reported in the literature. Statistical developments were considered to compute parameter uncertainties for a non-linear system with non-linear restrictions. The model achieved very good fits to experimental data, with low RMSE values between 0.22 × 10−4 and 4.2 × 10−4 A/cm2, while also showing surface coverage fraction distributions in agreement with other experiment-based works from the literature. All catalysts taken into account, the most sensitive parameters were the reaction rate constants associated with the formation of adsorbed CH3CO, and the direct and reverse water dissociative adsorption reactions, respectively. Additional analyses suggested that there is not much correlation between the parameters. The results from this work could contribute to the state-of-the-art DEFC models by providing insights into which variables may be assumed constant or which ones have the greatest impact on the model output, thus helping to reduce the model size and computational time for future broader DEFC models.

This study demonstrates the structural properties and evaluates the electrocatalytic activity of an ethanol oxidation reaction using ternary materials composed by Pd and Sn nanoparticles combined with CeO 2 nanorods (NR) anchored on Vulcan carbon black to be used as an anode in alkaline direct ethanol fuel cells (ADEFCs). The highest open circuit voltage (1010 mV), maximum power (30 mW cm−2) and current densities (113 mA cm−2) were achieved using (Pd 1 Sn 3) 10 (CeO 2 NR) 20 (Vn) 70 , while the commercial anode values were 968 mV, 23 mW cm−2 and 123 mA cm−2. Although similar performance for both anodes was observed, the ternary hybrid electrocatalyst contains an 8-fold lower Pd content than the commercial material. This outcome may be justified by the higher defect density presented by the carbon support observed by Raman spectroscopy and the metal oxidation state modifications detected by X-ray photoelectron spectroscopy, as well as the electrochemically active surface area presented by the ternary electrocatalyst. The combination of higher vacancies, defects and oxygenated species in the carbon support and the synergistic effect between the oxyphilic Sn and CeO 2 NR species and the Pd nanoparticles results in an electrochemical performance that makes these ternary electrocatalysts promising anode materials for ADEFC applications. [Display omitted] • Ternary electrocatalysts based on Pd 1 Sn 3 nanoparticles and CeO 2 nanorods for EOR. • Ternary electrocatalysts with better performance in ADEFC tests. • Synergic effect, defects, oxygenated species and vacancies are important for the EOR. [ABSTRACT FROM AUTHOR]

Summary: In this study, the response surface methodology (RSM) was applied to design the Box‐Behnken design (BBD) experiments and optimize the interactive effects of major operating parameters of direct ethanol fuel cells (DEFCs) for achieving the maximum power density. The main effective operating parameters of DEFCs like ethanol concentration, anode electrocatalyst loading, and operating temperature were selected as independent variables in BBD while the power density was considered to be the response function under investigation. The Nafion 117 membrane as solid electrolyte and synthesized Pt‐Ru‐Re (1:1:0.5)/f‐MWCNT as anode and commercial Pt/CHiSPEC as cathode electrocatalysts were used, respectively. The individual and combined effects of independent variables on the maximum power density of DEFC were also examined. A second‐order model was established according to the RSM results and statistically validated by analysis of variance (ANOVA) to provide a satisfactory description of the experimental data. The maximum peak power density of 22.10 mW/cm2 was obtained by RSM modeling and the same was validated experimentally using the optimum condition of a 2.03 M ethanol concentration, 1.14 mg/cm2 anode electrocatalyst loading, and 79.48°C operating temperature. The validation of the model showed that the experimentally measured value of the highest power density achieved under optimized conditions (21.53 mW/cm2) was very close to the computed value (22.10 mW/cm2) by the model. The optimization results via the RSM demonstrated that the power density of DEFC was significantly affected by operating cell temperature, followed by anode electrocatalyst loading and ethanol concentration. [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]

EOR is a semi-reaction of direct ethanol fuel cells (DEFCs), and determines the performance of the DEFCs. Therefore, it is very important for EOR to rationally design an electrocatalyst with excellent activity, stability and CO-resistance. Based on this, we report the synthesis of MOF based composite catalysts by a facile method, which is formed by combining polyaniline hydrogel (PANH) with MOF 1 and carbon cloth (CC). At the same time, the structures of the composites were characterized by XRD, SEM and XPS. Under the optimum conditions, the j value for EOR is 107 mA cm−2 under alkaline conditions at 0.6 V, which indicates that composite 2 has excellent catalytic activity for EOR, and is superior to that of the previously reported nickel-based catalysts for EOR. The Tafel slope and the exchange current density of composite 2 are 88.9 mV dec−1 and 1.95 × 10−5 A cm−2 respectively. In addition, the j value of composite 2 was 65% of the original value after 1000 CV cycles. However, when the electrolyte was changed into the original one (1 M KOH + 1 M EtOH), the j value returned to 74% of the original value. Based on the excellent electrocatalytic performance, good stability and anti-CO poisoning, composite 2 is expected to be an economic, efficient and CO poisoning resistant electrocatalyst for EOR. Ni-MOF based composites, which is formed by combining polyaniline hydrogel (PANH) with MOF 1 and carbon cloth (CC), were used as excellent activity, good stability and carbon monoxide resistant catalysts for methanol oxidation reaction under alkaline medium. [Display omitted] • Composites of Ni-MOF and polyaniline hydrogel were synthesized by a facile method. • Composite 2 has excellent activity, stability and carbon monoxide resistant. • The excellent activity of composite 2 is due to the enhanced conductivity of MOFs. [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 the present study, various mesoporous Ti x W 1-x O 2 (x = 0.5; 0.6; 0.7; 0.8) supports were fabricated via a facile solvothermal approach and explored the effect of doping tungsten concentration on electrochemical properties of Ti x W 1-x O 2 -supported Pt electrocatalysts toward ethanol electrochemical reaction. Interestingly, the incorporation of tungsten into TiO 2 lattices with the doping tungsten amounts (20 and 30 at %) resulted in boosting both the surface area and electrical conductivity, however, a reverse trend was observed when increasing the doped tungsten content more than 40 at %. Additionally, the relatively well-distributed Pt nanoparticles with the small particle size (ca. 3 nm) anchored on supports were achieved using a microwave-assisted polyol route. Electrochemical results indicated that various Ti x W 1-x O 2 -supported Pt catalysts exhibited the catalytic performance greater than that of the commercial carbon-supported Pt (E-TEK) catalyst for ethanol electro-oxidation reaction (EOR). For as-obtained electrocatalysts, the Ti 0.7 W 0.3 O 2 -supported Pt catalyst showed the highest mass activity (~260.23 mA/mg Pt) and greatest I f /I b ratio (~1.34), which ~2.0-fold and ~1.57-time higher than that of carbon-supported Pt (E-TEK) catalyst (~130.62 mA/mg Pt for mass activity and ~0.85 for I f /I b ratio, respectively). After 5000 cycling tests, the mass activity loss of Ti x W 1-x O 2 -supported Pt catalysts was around twice lower than that of the commercial Pt/C (E-TEK) catalysts, suggesting that the Ti x W 1-x O 2 -supported Pt catalysts exhibited the superior stability toward ethanol electrochemical oxidation. The outstanding electrochemical activity and stability of Ti x W 1-x O 2 -supported Pt electrocatalysts were owing to the synergetic effect between Pt nanocatalyst and non-carbon Ti x W 1-x O 2 supports as well as superior natural durability of TiO 2 -based materials. [Display omitted] • Effect of differential W: Ti ratio on properties of W-doped TiO2 supports was investigated. • Effect of differential W: Ti ratio on ethanol electro-oxidation reaction (EOR) was studied. • Various Pt/TixW1-xO2 catalysts showed better performance than commercial Pt/C catalysts. • Various Pt/TixW1-xO2 electrocatalysts demonstrated superior electrochemical stability. [ABSTRACT FROM AUTHOR]

Direct and complete electro‐oxidation of ethanol to CO2 is highly desirable for the commercialization of the direct ethanol fuel cells but is challenging. Current electrocatalysts (mainly Pt, Pd) for ethanol oxidation reaction (EOR), unfortunately, still suffer from low CO2 selectivity and rapid performance deterioration. In this study, a new Pt/α‐PtOx/WO3 electrocatalyst containing amorphous PtOx structures is successfully synthesized via a facile hydrothermal reaction following Ar atmosphere annealing. The migration of lattice oxygens in the WO3 during the annealing process is confirmed as the mechanism for the formation and manipulation of amorphous interfaces containing PtOx species in the Pt/α‐PtOx/WO3 electrocatalyst. The obtained Pt/α‐PtOx/WO3 with tunable amorphous PtOx interfaces favors the desorption of poisoning EOR intermediates (such as CO) and high CO2 selectivity. Therefore, the state‐of‐art of the Pt/α‐PtOx/WO3 exhibits excellent EOR activity (2.76 A mg–1), stability (47.99% of the initial activity preserved after 3600 s), and particularly high CO2 selectivity (reached 21.9%, higher than most reported values for Pt or other noble metals based EOR catalysts). This study may provide a new strategy to improve the EOR performance of metal‐based catalysts and to rationally design and prepare other high‐performing electrocatalysts via engineering the amorphous interfaces. [ABSTRACT FROM AUTHOR]

Electrocatalytic preparation of Pt-based nanocomposites has been investigated for improvement of direct ethanol fuel cells (DEFCs). In this study, new alternative catalysts of Pt-decorated cerium zirconium oxide-modified multiwalled carbon nanotubes (Pt/CeZrO 4 /MCNT) were successively prepared to improve the activity of the ethanol oxidation reaction (EOR). The prepared CeZrO 4 with a face-centered cubic (fcc) structure compatibly dispersed onto MCNT provides abundant active Pt sites for highly active catalysts. The fcc-structured Pt was also satisfactorily decorated onto CeZrO 4 /MCNT, resulting in highly active Pt. The Ce4+/Ce3+ redox property can promote oxygen vacancies to improve the electrochemical activity for oxidation of carbonaceous species. An increase in roughness and a stabilized catalyst structure can also be produced by inserting Zr4+ into the ceria metal oxide. The prepared Pt/20%CeZrO 4 /MCNT catalysts present excellent electrochemical active surface area, mass activity, CO tolerance and high electron kinetic transfer with low resistance and high stability over commercial PtRu/C toward EOR. This promising catalyst material could be introduced to enhance the anodic oxidation reaction in DEFCs. [Display omitted] • Electrodeposition of Pt on CeZrO 4 /MCNT was successfully performed. • The structure of CeZrO 4 /MCNT induces high electrochemically active Pt decoration with high ethanol oxidation electroactivity. • Pt/CeZrO 4 /MCNT promotes high efficiency for carbonaceous species removal. • Pt/CeZrO 4 /MCNT offers excellent activity and stability for ethanol oxidation over commercial PtRu/C. [ABSTRACT FROM AUTHOR]

Electrochemical atomic layer deposition was used to form bimetallic (BiPd, CuPd) and trimetallic (CuBiPd) thin films via surface‐confined reactions. Pd thin films were characterized by cyclic voltammetry, scanning electron microscopy (SEM) and the alloy formation with preferred Au/Pd(111) orientation was confirmed by XRD. AFM revealed uniform grain distribution, with 3D islands growing on CuBiPd. EDX verified the presence of all deposited elements. Compared to other prepared catalysts, CuBiPd catalyst showed higher activity and stability towards the ethanol oxidation reaction (EOR), as confirmed by the peak current and onset potential trends, respectively: CuBiPd (1.35 mA, −0.450 V)>CuPd (0.6016 mA, −0.442 V)>BiPd (0.275 mA, −0.384 V)>Pd (0.186 mA, −0.350 V). The EOR current on CuBiPd improved by 2.5 folds relative to Pd. The results show that CuBiPd electrocatalyst is a promising material for EOR with enhanced catalytic properties for direct ethanol fuel cell [ABSTRACT FROM AUTHOR]

Summary: In this study, Mo2C and MoS2 were used as cocatalyst for a non‐noble metal for the first time for ethanol electro‐oxidation reaction (EOR) in alkaline media. Anode electrocatalysts containing Nickel, Mo compound, and carbon support were synthesized at different weight ratios of Ni and Mo2C (or MoS2) while keeping the carbon support weight constant in each catalyst combination to investigate the best weight ratio among our range. Physical characterizations of the electrocatalysts were investigated by XRD, XPS, SEM‐EDS, EDAX, and TEM techniques. Electrochemical performance of the catalysts was studied via cyclic voltammetry (CV), linear sweep voltammetry (LSV), and chronoamperometry (CA) by using a home‐made electrochemical cell test system exhibiting similar alkaline direct ethanol fuel cell (ADEFC) architecture by giving the opportunity of using an anion exchange membrane. All of the Ni‐Mo2C/C and Ni‐MoS2/C at different weight ratios were shown better performance than pristine Ni and Ni/C. The highest current density was measured with Ni‐Mo2C/C‐2 (11.4 mA cm−2) anode catalyst, which exhibits the highest electrochemical reaction rate. The diffusion coefficient of the catalysts was calculated by using the data from linear LSV. CA experiment results showed that the tolerance for catalytic poisoning and durability of Ni‐Mo2C/C‐2 was better among all the electrocatalysts. Highlights: Literature survey showed that Mo2C and MoS2 are promising co‐catalysts for EOR. However, there is a lack of study on the use of Mo2C or MoS2 as co‐catalyst with a non‐noble metal.Molybdenum compound containing transition metal‐based anode electro‐catalysts were synthesized for EOR in alkaline media.A home‐made electrochemical cell is designed to make the system more similar to an ADEFC system.The results of the electrochemical characterizations are showed that the Mo compound addition increased the catalytic activity and stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-quality two-dimensional Ag-CuPd hollow nanoplates were prepared by a template-free one-step aqueous synthetic strategy. • The product exhibited hih electrocatalytic activity (7.99 A mg−1), remarkable stability (chronoamperometric and cycling tests), and superior C 1 products selectivity (52 %) for complete ethanol oxidation electrocatalysis. • Superior performance was ascribed to the strong intermediate confinement within active hollow cavity that kinetically facilitated the oxidation cleavage of C—C bond of ethanol for desired C 1 products. The development of high-performance electrocatalysts for complete ethanol oxidation reaction (EOR) is of great significance to hold the higher energy efficiency in direct ethanol fuel cells. Despite some important achievements, their progress, especially C 1 product selectivity, is still notably slower than needed. In this work, a template-free one-step aqueous synthetic strategy is reported to synthesize high-quality two-dimensional Ag-CuPd hollow nanoplates (HNPs) as a high-performance electrocatalyst for complete EOR electrocatalysis. The reaction is carried out via galvanic replacement reaction induced self-limiting growth with Ag+/Ag as the hollow seed and Br- as the structure-directing agent. The products feature uniform two-dimensional hollow nanostructures that expose abundant active metal sites and ensure a strong intermediate confinement microenvironment for electrocatalysis. The best Ag-CuPd HNPs exhibit enhanced electrocatalytic activity (7.99 A mg Pd -1), remarkable stability (chronoamperometric and cycling tests), and superior C 1 products selectivity (52 %) for complete EOR electrocatalysis. Detailed mechanism investigations ascribe selectivity enhancement to the strong intermediate confinement within active hollow cavity that kinetically facilitates the oxidation cleavage of C—C bond of ethanol for desired C 1 products. [ABSTRACT FROM AUTHOR]

Ir has long been regarded as an alternative ethanol-to-CO 2 electrocatalyst, but little is known about the ethanol oxidation reaction (EOR) mechanism on Ir, especially the C1 pathway selectivity. Thereby, in situ quasi-quantitative electrochemical infrared absorption spectroscopy (QEIAS), consisting of total-reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), infrared absorption spectroscopy (IRAS), and transmission infrared absorption spectroscopy (TIAS) with a thin-layer flow cell, is established to probe it. Initially, the well-accepted EOR dual-pathway mechanism is confirmed via ATR-SEIRAS and IRAS. Ir-H ad species (ca. 2040 cm−1), originating from the ethanol dissociation at low potentials, are observed for the first time to replenish the reaction process. Based on it, the apparent Faradaic efficiency of the C1 pathway (FE C1) is readily estimated to be as high as 76.4% (0.7 V) in acidic media. The quantitative analysis of reaction residual verifies these FE C1 results through high-performance liquid chromatography (HPLC), and a relative error of only 2–9% exists between the two methods. Thus, Ir might be more efficient for ethanol complete oxidation than other Pt-group metallic catalysts, especially in acidic media. This work could be necessary for the rational design of Ir-based EOR catalysts with high C1 pathway selectivity and low over-potential for direct ethanol fuel cells. [Display omitted] • Replenishing EOR dual-pathway mechanism by ATR-SEIRAS and IRAS. • Revealing that Ir-H ad species are from the ethanol dissociation. • Estimation of quasi-quantitative FE C1 based on multiple methods. • FE C1 on Ir is up to 80% at low potentials in acidic media. [ABSTRACT FROM AUTHOR]

The rational design of inexpensive and highly efficient electrocatalysts for ethanol oxidation reaction (EOR) is crucial for direct ethanol fuel cells. In this study, a series of carbon-supported PtCu electrocatalysts with varying Pt/Cu ratios were synthesized using a microfluidic system. This system enabled the separation of heterogeneous nucleation and nanocrystal growth based on segmental thermal induction. Heterogeneous nucleation occurred at the low-temperature zone, which resulted in uniform loading, while the enhancement of solvent reducibility in the high-temperature region enabled the control of the PtCu nanoparticle composition. The synthesized PtCu/C electrocatalyst, with Cu content adjustable from 17% to 38%, exhibited high crystallinity and homogeneous dispersion, with an average particle size of 3.9 nm. These advantageous physical properties endowed the PtCu/C electrocatalysts with significantly enhanced electrocatalytic performance for EOR compared with commercial Pt/C catalysts. The development of this method presents a novel approach for the controlled preparation of supported catalysts. • The microfluidic synthesis method can effectively achieve the separation of heterogeneous nucleation and crystal growth of nanocrystals. • Monodispersed and composition-controlled PtCu/C alloy electrocatalysts were successfully synthesized in milli-second time resolution. • The products displayed higher electrochemical performance towards the ethanol oxidation reaction. [ABSTRACT FROM AUTHOR]

A series of Pt-Ru metallic aerogels (MAs) with controllable composition were successfully synthesized using a freeze–thaw method. Among all the samples we prepared, Pt 6 Ru MAs with rich surface defects, large specific surface area, and optimal electronic structure show the highest catalytic activity and reactivation ability in ethanol oxidation reaction (EOR). [Display omitted] • Pt 6 Ru MAs with abundant rich surface defects were prepared for the first time. • Pt 6 Ru MAs have excellent EOR activity and stability. • Pt 6 Ru MAs can be reactivated in a 0.1 M HClO 4 after stability measurement. Direct ethanol fuel cells (DEFCs) are a new type of green and efficient energy conversion devices, but the slow anodic reaction kinetics limit their application. Herein, a series of Pt-Ru metallic aerogels (MAs) with controllable composition, rich surface defects, and large specific surface area were prepared for ethanol oxidation reaction (EOR) by freeze–thaw method. Pt 6 Ru MAs exhibit the highest mass activity (1.264 A mg Pt −1) toward EOR among all the catalysts we have prepared, which is 2.0, 1.8, and 3.7 times higher than those of Pt MAs (0.632 A mg Pt −1), the commercial Pt/C (0.696 A mg Pt −1), Pt 6 Ru NPs (0.339 A mg Pt −1). 1H nuclear magnetic resonance spectroscopy confirms that only acetic acid was the liquid product of Pt 6 Ru MAs during EOR catalysis. Furthermore, Pt 6 Ru MAs show little attenuation and satisfactory reactivation abilities in stability assessment, demonstrating their good stability. This proves that the introduction of Ru makes feasible adjustments to the electronic structure of Pt in MAs, improving the electrocatalysis activity of Pt 6 Ru MAs in EOR. Mechanistic investigations reveal that the optimal electronic structure is the intrinsic reason for the excellent EOR performance of Pt 6 Ru MAs. The findings open a new way to develop high-performance Pt-based materials electrocatalysts. [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]

[Display omitted] • The synergistic effect of NiCoFe-hydroxide was studied. • ORR and EOR intermediate steps are identified. • CO– poisoning was eliminated during EOR due to NiCoFe-hydroxide support. • Portable electronics application of DEFC was demonstrated. The rational design and identification of the underlying role of the support materials to promote the electrocatalytic activity of the active catalyst are the main objectives of the current research. Herein, we synthesized different compositions of ternary nickel cobalt iron transition metal hydroxide (TMH) supported palladium (Pd) nanoparticles (Pd/Hy) to improve the ethanol electrooxidation reaction (EOR) and oxygen reduction reaction (ORR) kinetics of Pd NPs. The TMH supports modified the surface electronic structures of Pd through strong metal support interaction, thereby improving the EOR and ORR reaction kinetics. Herein, we explored potential-dependent electrochemical impedance spectroscopy (EIS) to identify the intermediates species formed during the ORR and EOR process and rationalize the reaction mechanism. The potential-dependent EIS reveals that TMH supports eliminating the adsorption of the poisonous carbonaceous species during the EOR. The synthesized bifunctional Pd/Hy catalyst integrated alkaline direct ethanol fuel cell device exhibits a peak power density of 28.1 mW/cm2, which is a higher performance than that of the Pt/C integrated devices. Finally, Pd/Hy catalyst-integrated passive DEFC was tested, and a portable electronic application was demonstrated. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells (DEFCs), with their boosted energy density and efficiency, are poised to supplant secondary batteries in the near future. However, the pricy and low-durability of Pt-based anode catalyst used in these cells have hampered the development of this technology. We successfully created a Ni-MOF @ nickel foam (NF) to operate as an anode for a DEFC. We next enhanced the electrical conductivity of these produced electrodes with graphene and tested them towards ethanol oxidation in a basic solution. The study looked at the electrodes' surface shape, crystalline structure, chemical and electrical properities, among other things. Furthermore, the electrochemical activity and durability of the prepared electrodes were examined. These tests demonstrated the successful formation of the MOF @ the surface of the NF, with and without reduced graphene oxide. The produced materials outperformed plain Ni foam in terms of ethanol oxidation activity, and the graphene doping significantly enhanced this activity. A 0.35 V onset potential was obtained, with current output increasing concurrently with ethanol oxidation up to 0.5 M before stabilizing. The superior activity was attributed to the prepared electrodes' perfect nano-sheet structure, high porosity, and outstanding mass and charge transport characteristics. The addition of reduced graphene oxide enhanced charge transfer and thus improved the overall performance. [Display omitted] • Ni-MOF @ nickel foam with and without reduced graphene oxide was successfully prepared. • The activity of the prepared electrodes towards ethanol oxidation was investigated. • Results discussed based on charge and mass transfer properties of the prepared materials. [ABSTRACT FROM AUTHOR]

Ethanol oxidation reaction (EOR) at the anode of direct ethanol fuel cells (DEFCs) obeys C1/C2 dual-pathway reaction mechanism, and improving the selectivity of C1 pathway is crucial to the commercialization of DEFCs. Herein, a novel hydrogen-implanted PdGa single-atom alloy metallene (H-Ga 1 Pdene) is designed for optimizing the C1 pathway to achieve greatly enhanced C1 pathway selectivity through electronic and strain engineering. Benefiting from the strong p-d orbital hybridization interaction and tensile strain effect induced by hydrogen-implantation, H-Ga 1 Pdene exhibits high mass activity of 10.34 A mg Pd −1 and C1 pathway selectivity of 54.7%, both showing an order of magnitude higher than that of commercial Pd/C. Theoretical calculations reveal that the p-d hybridization interaction could effectively accelerate the C-C bond cleavage and tensile strain enable efficient oxidation of CO* and CH 3 * produced by the C-C bond cleavage in C1 pathway, enabling H-Ga 1 Pdene to efficiently catalyze the complete electrooxidation of ethanol through the C1 pathway. [Display omitted] • Hydrogen-implanted PdGa single-atom alloy metallene (H-Ga1Pdene) was fabricated. • Both p-d orbital hybridization and tensile strain were induced by interstitial hydrogen. • p-d hybridization and tensile strain facilitated EOR activity and C1 pathway selectivity. • The C1 pathway selectivity of H-Ga1Pdene for EOR was 54.7%. • Uncover the underlying mechanism of p-d hybridization and tensile strain for efficient EOR. [ABSTRACT FROM AUTHOR]

The development of ethanol electrooxidation catalysts with high activity and robust stability is essential for the commercialization of direct ethanol fuel cells. However, because of their low C1 selectivity, the electrocatalytic efficiency of catalysts for complete ethanol oxidation is still far from satisfying. Herein, a novel 2D Pd--Au heterogeneous catalyst for enhancing C1 selectivity to achieve highly efficient ethanol oxidation through phase and interphase engineering is designed. It is found that owing to the plentiful amorphous/crystalline interphases, the selectivity of C1 pathway on Pd--Au heterocatalyst can be improved up to 33.2% at a low potential, 10.4 times higher than commercial Pd/C (3.2%). Furthermore, 89.1% of initial mass activity of Pd--Au HNS can be retained after the accelerated degradation test of 2000 potential cycles, much higher than those of Pd NS (39.3%), commercial Pd/C (34.4%), and Pt/C (11.4%). The CO stripping and in situ Fourier transform infrared experiments reveal that 2D Pd--Au heterocatalyst, with intricate design of the amorphous Pd domain and the crystalline Au cluster interface, has better antipoisoning properties and stronger C--C bond cleavage ability than pure Pd nanosheets. Density functional theory calculations further demonstrate that the introduction of Au clusters switches on the electroactivity of amorphous Pd as the electron pump to accomplish the complete oxidation of ethanol, in which the selectivity for C1 pathway is significantly boosted whereas the typical C2 pathway is substantially blocked. [ABSTRACT FROM AUTHOR]

The stoichiometry of ethanol oxidation (average number of electrons transferred per molecule) is a crucial parameter in fundamental studies of ethanol oxidation and the development of direct ethanol fuel cells and electrolysis cells. Measurements of stoichiometry are particularly important at elevated temperatures, where these cells become more efficient. In this work, rotating disk and flow cell methods have been used to explore the temperature dependence of ethanol oxidation at Pt/C and PtRu/C electrodes. Stoichiometries determined from the slopes of Koutecky-Levich plots ranged from 2.1 to 2.8 at 24 °C and increased to a range of 3.4 to 5.6 at 80 °C. They were higher for PtRu/C, and increased more with increasing temperature. At 80 °C, there was a significant decrease in stoichiometry with increasing potential at both catalysts, indicating a decrease in selectivity for the complete oxidation of ethanol to CO2. Analysis of ethanol consumption and product distributions using a flow cell provided independent measurements of stoichiometry that were in reasonable agreement with values from Koutecky-Levich plots. [ABSTRACT FROM AUTHOR]

This paper presents research on the effects of common solvents such as n-butyl acetate, isopropanol, and ethanol on the properties and electroactivity of catalyst ink based on PtAl/rGO. The inks prepared by mixing PtAl/rGO catalyst, Nafion solution (5 wt%), and solvent were coated on carbon cloth by the spin coating method. The results obtained showed that ethanol was the most suitable solvent for the preparation of catalyst ink with a volume ratio between catalyst slurry and solvent of 1 : 1 (CI-EtOH (1/1) ink). The surface of the CI-EtOH (1/1) coated electrode was smooth, flat, and even and had no cracks due to the increase of Nafion mobility, resulting in significant improvement in the interaction between Pt particles and ionomer. Moreover, the electrochemical activity of the CI-EtOH (1/1) ink in ethanol electrooxidation reaction, in both acidic and alkaline media, has the highest value, with the forward current density, IF, reaching 1793 mA mgPt−1 and 4751 mA mgPt−1, respectively. In the application in direct ethanol fuel cell (DEFC), the CI-EtOH ink-coated anode also exhibited the highest power density in both PEM-DEFC (with a proton exchange membrane) and AEM-DEFC (with an anion exchange membrane) at 19.10 mW cm−2 and 27.07 mW cm−2, respectively. [ABSTRACT FROM AUTHOR]

Fossil fuel alternatives are being increasingly studied, and alkaline direct ethanol fuel cells (ADEFC) have acquired importance, as to ethanol is a renewable fuel. In this context, the aims of the present study were to synthesize, characterize and evaluate electrocatalytic activity in oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR) using hybrid electrocatalysts based on Pd nanoparticles and CeO 2 nanorods supported on carbon black for application in ADEFC. The highest OCV, maximum current and power densities obtained using Pd 15 (CeO 2 NR) 10 (Vn) 75 as the cathode and Pd 10 (CeO 2 NR) 20 (Vn) 70 as the anode were 1270 mV, 190 mA cm−2 and 65 mW cm−2, respectively. These interesting results are justified by the highest I D /I G ratio and ECSA, which suggest a high number of oxygenated species, defects and vacancies in these electrocatalysts and by the synergistic effect between CeO 2 NR and Pd nanoparticles. Therefore, these hybrid electrocatalysts are promising for ADEFC applications. [Display omitted] • Hybrid electrocatalysts based on Pd and Ceria nanorods for EOR and ORR. • The electrocatalysts were applied as cathode and anode in ADEFC experiments. • Better performance compared to commercial materials in ADEFC tests. • Oxygenated species, vacancies and defects are the main electrocatalytic effects. [ABSTRACT FROM AUTHOR]

A composite of bimetallic micro/nanostructured palladium–platinum (Pd–Pt) alloy, reduced graphene oxide (rGO) and polydopamine (PDA) on three-dimensional nickel foam (NF) was obtained by chemical immersion method and anneal method for ethanol electrocatalysis. The key points of the synthesis method are employing PDA as an adsorbent of graphene oxide (GO), rGO with a high specific surface area as the carbon carrier of the Pd–Pt alloy after annealing, and NF as the secondary substrate. Scanning electron microscopy revealed that Pd–Pt particles with dendrite-like micro/nanostructure are well dispersed on the surface of rGO, which provide a great deal of catalytic sites. The structure and phase characterization were determined by X-ray diffraction. The diffraction peaks of bimetallic catalysts are shifted in comparison with those of two monometallic catalysts, which prove the formation of the Pd–Pt alloy. The lattice strain and electronic effect of Pd–Pt alloy micro/nanostructured particles lead to the improvement of the electrocatalytic properties of materials. In the electrochemical measurement, the composite of the Pd–Pt alloy with appropriate atomic ratio, rGO, PDA and NF (Pd6Pt@GPN) provided the largest electrochemically active surface area and the highest peak current density with significantly enhanced cycling stability in the forward scan toward EOR in alkaline medium among all catalysts prepared. Thus, this Pd6Pt@GPN catalyst highlights the potential application in the anode catalyst of a direct ethanol fuel cell. [ABSTRACT FROM AUTHOR]

The advancement of direct ethanol fuel cell (DEFC) represents a real challenge to electrochemical science because ethanol changes significantly the triple phase boundary properties such as the redox reactions and the proton transport. Ethanol molecules promote poor fuel cell performance due to their slow oxidation rate, reduction of the proton transport due to high affinity of ethanol by the membrane, and due to mixed potential when the ethanol molecules reach the cathode by crossover. DEFC performance has been improved by advances in the membranes, e.g., low ethanol crossover polymer composites, or electrode materials, e.g., binary/ternary catalysts. Herein, high temperature (130 °C) DEFC tests were systematically investigated by using optimized electrode and electrolyte materials: Nafion-SiO 2 hybrid electrolyte and well-alloyed PtSn/C electrocatalyst. By optimizing both the electrode and the electrolyte in conjunction, DEFCs operating at 130 °C exhibited a threefold increase on performance as compared to standard commercially available materials. • Nafion-SiO 2 hybrids show improved hygroscopic properties and thermal stability. • Hybrid with 6.5 wt% SiO 2 presents better proton conductivity than unmodified Nafion. • Improved performance DEFC prototypes with Nafion-SiO 2 hybrid electrolytes. • Substantial differences in DEFC performances depending on the PtSn/C anode catalysts. • 112 mA cm−2 power density of 130 °C for 6.5 wt% SiO 2 hybrid and homemade PtSn/C. [ABSTRACT FROM AUTHOR]

In this study, we present the synthesis of pristine carbon (p -CNO), nitrogen doped (N–CNO) and oxygen functionalized (ox-CNO) nano onions, using flame pyrolysis, chemical vapour deposition, and reflux methods, respectively. Pd/p-CNO, Pd/N–CNO and Pd/ox-CNO electrocatalysts are prepared using a simple and quick microwave-assisted synthesis method. The various CNO and Pd/CNO electrocatalysts are fully characterized and the FTIR and XPS results reveal that the synthesized CNOs contain oxygen and nitrogen functional groups that facilitates the attachment and dispersion of the Pd nanoparticles. Electrochemical tests show that the N–CNO and Pd/N–CNO electrocatalysts exhibit high current density (4.2 mA cm −2 and 17.4 mA cm −2), long-term stability (1.2 mA cm −2 and 6.9 mA cm −2), and fast electron transfer when compared to the equivalent pristine and oxidized catalysts (and their Pd counterparts), and a commercial Pd/C electrocatalyst, towards ethanol oxidation reactions in alkaline medium. Image 1 • Carbon nano onions (CNOs) were synthesized using a flame pyrolysis method. • Palladium-based electrocatalysts were prepared by a microwave synthesis method. • N-doping and functionalization facilitated the attachment of Pd onto the CNOs. • The N–CNO and Pd/N–CNO exhibit high current density for ethanol electro-oxidation. [ABSTRACT FROM AUTHOR]

Physical and electrochemical properties of Pd catalysts combined with Ru and Mo on carbon support were investigated. To this end, Pd, Pd1.3Ru1.0, Pd3.2Ru1.3Mo1.0 and Pd1.5Ru0.8Mo1.0 were synthesized on Carbon Vulcan XC72 support by the method of thermal decomposition of polymeric precursors and then physically and electrochemically characterized. The highest reaction yields are obtained for Pd3.2Ru1.3Mo1.0/C and Pd1.5Ru0.8Mo1.0/C and, as demonstrated by thermal analysis, they also show the smallest metal/carbon ratio compared the other catalysts. XRD (X-ray Diffraction) and Raman analyses show the presence of PdO and RuO2 for the Pd/C and the Pd1.3Ru1.0/C catalysts, respectively, a fact not observed for the Pd3.2Ru1.3 Mo1.0 /C and the Pd1.5Ru0.8Mo1.0/C catalysts. The catalytic activities were tested for the ethanol oxidation in alkaline medium. Cyclic voltammetry (CV) shows Pd1.3Ru1.0/C exhibiting the highest peak of current density, followed by Pd3.2Ru1.3Mo1.0/C, Pd1.5Ru0.8Mo1.0/C and Pd/C. From, chronoamperometry (CA), it is possible to observe the lowest rate of poisoning for the Pd1.3Ru1.0/C, followed by Pd3.2Ru1.3Mo1.0/C, Pd1.5Ru0.8Mo1.0/C and Pd/C. These results suggested that catalytic activity of the binary and the ternary catalysts are improved in comparison with Pd/C. The presence of RuO2 activated the bifunctional mechanism and improved the catalytic activity in the Pd1.3Ru1.0/C catalyst. The addition of Mo in the catalysts enhanced the catalytic activity by the intrinsic mechanism, suggesting a synergistic effect between metals. In summary, we suggest that it is possible to synthesize ternary PdRuMo catalysts supported on Carbon Vulcan XC72, resulting in materials with lower poisoning rates and lower costs than Pd/C. [ABSTRACT FROM AUTHOR]

Catalysts are an important part of the ethanol fuel cell. However, catalysts present certain problems such as high cost, low conversion efficiency, and poor durability, which hinder the commercialization of direct ethanol fuel cells. The method of loading the catalyst on the carrier and alloying can effectively improve the dispersion, enhance the anti‐poisoning ability, improve stability, and reduce cost of the catalyst. In this work, NiFe‐layered double hydroxide (NiFe‐LDH) with a "card‐house" structure was grown vertically on nickel foam by electrochemical deposition. Pt3Sn nano‐alloy particles were then deposited on NiFe‐LDH/NF by electrochemical deposition to generate the ethanol electrocatalytic material (denoted as Pt3Sn NPs/NiFe‐LDH/NF). The "card‐house" structure formed by NiFe‐LDH thin nanosheets (thickness of 14.63 nm) improved the dispersion and uniformity of the Pt3Sn nano‐alloy particles (5.34 nm). The introduction of the oxyphilic metals Ni and Fe enhanced the anti‐toxicity of the Pt3Sn nano‐alloys. The synthesized catalyst exhibited a large electroactive surface area with a specific activity of 21.74 mA cm−2 and a If/Ir of 1.23, which were higher than those of traditional ethanol electrocatalysts. The catalyst also presented better catalytic performance for ethanol oxidation, excellent stability and anti‐poisoning ability. [ABSTRACT FROM AUTHOR]

Direct Ethanol Fuel Cells (DEFCs) have fascinated remarkable attention on account of their high current density and being environmentally friendly. Developing efficient and durable catalysts with a simple and fast method is a great challenge in the practical applications of DEFCs. To this end, the bimetallic Pd–Ag with adjustable Pd:Ag ratios were synthesized via a simple and one-pot strategy on activated carbon as a support in this study. The Pd–Ag/C catalysts with different molar ratios were synthesized by simultaneous reduction of Pd and Ag ions in the presence of the ethanolic sodium hydroxide as a green reducing agent for the first time. Several different methods, including FE-SEM, HR-TEM, XRD, XPS EDX, ICP-OES, and BET were used to confirm the structure and morphology of the catalysts. The performance of catalysts was also examined in ethanol oxidation. Obtained results of electrochemical experiments revealed that the Pd 3 –Ag 1 /C catalyst had superior catalytic activity (2911.98 mAmg−1 Pd), durability, and long-stability compared to the other catalysts. The excellent catalytic characteristic can be attributed to the synergistic effect between Pd and Ag. We presume that our simple method have the chance to be utilized as a proper method for the synthesis of fuel cell catalysts. • Eco-friendly, simple strategy for the synthesis of the Pd–Ag/C catalysts. • A catalyst with higher electrocatalytic activity and durability towards ethanol oxidation reaction. • Ethanolic sodium hydroxide was used to synthesis of Pd–Ag/C catalysts. [ABSTRACT FROM AUTHOR]

Improving the catalytic activity and durability of the ethanol oxidation reaction (EOR) is crucial for realizing the commercialization of direct ethanol fuel cells (DEFCs). Herein, we design a facile route to fabricate AuPd nanowires as highly efficient electrocatalysts toward ethanol oxidation reaction (EOR), where AuPd nanowires were in-situ assembled through the co-reduction of HAuCl 4 and PdCl 2 in aqueous solution in the presence of Triton X-114 and with potassium borohydride as the reducing reagent. The surface microstructure and composition of AuPd alloyed nanowires with the diameter of 4 nm were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high resolution-transmission electron microscopy (HR-TEM). Among the AuPd NWs series, Au 8 Pd 3 NWs demonstrated the best electrocatalytic activity (mass activity 10,570 mA mg−1 Pd) and enhanced durability for ethanol electroxidation (retained 54% after 300 cycles) among the samples. The enhanced activities in EOR can be ascribed to the synergic electronic and structural effects of AuPd NWs. This work can provide a feasible method to boost Pd-alloy based electrocatalysts for EOR in direct ethanol fuel cells. Image 1 • A facile method is developed for fabricating well-defined AuPd alloy nanowires. • Au 8 Pd 3 nanowires exhibit the best EOR performance in the series. • The synergistic electronic and structural effects contribute to the EOR enhancement. • It offers a facile strategy for synthesizing efficient Pd-alloy based EOR catalyst. [ABSTRACT FROM AUTHOR]

Carbon-supported PtSnCu/C, Pt3Sn/C, Pt3Cu/C and Pt/C electrocatalysts were synthesized by chemical reduction of metal precursors in ethanol reflux. These materials were characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and applied to the ethanol electro-oxidation in acidic medium. The reaction kinetics was studied by cyclic voltammetry and the mechanism was explored by in situ Fourier transform infrared spectroscopy (FTIR). The investigated materials presented chemical composition close to the nominal ones. XRD results indicated the formation of solid solution of Pt and Cu and/or Sn in the bi and tri-metallic materials. The particle size distribution was narrow with mean particle size of around 3 nm. A homogeneous distribution of the nanoparticles over the carbon support was evidenced. The investigated catalysts were active towards the ethanol oxidation reaction in acidic medium and led to the formation of CO2 and carbonyl compounds, as evidenced by FTIR. PtSnCu/C and Pt3Cu/C started to produce CO2 at 0.70 V vs. RHE, while this product was detected only at 0.75 V and 0.80 V vs. RHE on Pt and Pt3Sn/C, respectively, suggesting that Cu improves the dissociative adsorption of ethanol. [ABSTRACT FROM AUTHOR]

The understanding of electrocatalytic activity and poisoning resistance properties of Pt and Pd nanoparticles, recognized as the best electrocatalysts for the ethanol oxidation reaction, is an essential step for the commercialization of direct ethanol fuel cells (DEFCs). In this paper, mono and bimetallic Pt and Pd nanoparticles with different atomic ratios have been synthesized to study their electrocatalytic properties for an ethanol oxidation reaction in alkaline solutions. The different nanoparticles were physiochemically characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrochemical characterization was performed by cyclic voltammetry and chronoamperometry measurements. The electrochemical measurements indicate that Pt nanoparticles have much higher electrocatalytic activity for ethanol oxidation than Pd nanoparticles. The studies with bimetallic PtPd nanoparticles showed a significant impact of their composition on the ethanol oxidation. Thus, the highest electrocatalytic activity and poisoning resistance properties were obtained for Pt3Pd2 nanoparticles. Moreover, this study demonstrates that the poisoning of the catalyst surface through ethanol oxidation is related to the prevalence of the acetaldehyde–acetate route and the polymerization of acetaldehyde through aldol condensation in the alkaline media. [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]

One-dimensional (1D) metal-coated Pd structures are efficient catalysts for the ethanol electro-oxidation and promising strategy for minimizing the Pd-loading toward commercialization of direct ethanol fuel cells (DEFCs). Herein, the decorated and core-shell architectures of a novel Pd coating on Ag nanowires (PdAg-NWs) are controllable by a two-step polyol method based on the galvanic replacement reaction. The integration of uniform shell with a low Pd concentration and partial hollow structure onto 1D PdAg-NWs exhibits the highest efficiency for ethanol oxidation reaction (EOR) in alkaline solution. In comparison with Pd nanoparticles (PdNPs/C), the PdAgNWs/C performes 11 times superior EOR activity, and the onset potential shifts 80 mV negatively. The presence of Ag in PdAg-NWs enhances the absorption capacity of ethanol molecules and hydroxyl ions on the active sites, and improves the catalyst tolerance to CO-like intermediates, making them a potential anodic catalyst for DEFCs. Image 1 • Novel PdAg core-shell nanowires with a low Pd-loading were synthesized. • Controllable configuration of Pd layer by temperature and PVP concentration. • Adjustable particle size of Pd by reaction time and Pd/Ag molar ratio. • Efficient bifunctional electrocatalyst for direct ethanol fuel cells in alkaline media. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells (DEFCs) promise the use of ethanol as a bio‐renewable and non‐toxic fuel for energy conversion through the ethanol oxidation reaction (EOR). Well dispersed Pt3Sn and Pt nanoparticles on graphene (denoted Pt3Sn/G and Pt/G) support electrocatalysts made with alcohol reduction were tested towards EOR. The HRTEM and XRD characterizations provide the morphology and crystal phase of the Pt3Sn alloy nanoparticles, which has a uniform particle size of 2.8±0.08 nm, as is consistent with a Pt/G catalyst as reference. According to the in‐situ quick X‐ray‐absorption near‐edge structure (QXANES) spectra during an anodic scan of CV for the EOR test to explain clearly the potential‐dependent electronic state of the prepared electrocatalysts, the white‐line intensities of the Pt L3‐edge QXANES spectra and their spectral profiles vary appreciably with the electrode voltage. Moreover, Pt3Sn/G shows a better EOR performance than Pt/G because SnO2 can improve adsorption and dissociation during the oxidation by an appropriate expansion of the lattice parameters in the PtSn alloy. This work provides insight into the reaction mechanism of dissociative adsorption of ethanol on alloyed Pt surface, which has an important role in enhancing the EOR activity for a complete ethanol oxidation. [ABSTRACT FROM AUTHOR]