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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 N2 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.

The local coordination environment around catalytically active sites plays a vital role in tuning the activity of electrocatalysts made of carbon-supported metal nanoparticles. However, the rational design of electrocatalysts with improved performance by controlling this environment is hampered by synthetic limitations and insufficient mechanistic understanding of how the catalytic phase forms. Here we show that introducing F atoms into Pd/N–C catalysts modifies the environment around the Pd and improves both activity and durability for the ethanol oxidation reaction and the oxygen reduction reaction. Our data suggest that F atom introduction creates a more N-rich Pd surface, which is favourable for catalysis. Durability is enhanced by inhibition of Pd migration and decreased carbon corrosion. A direct ethanol fuel cell that uses the Pd/N–C catalyst with F atoms introduced for both the ethanol oxidation reaction and oxygen reduction reaction achieves a maximum power density of 0.57 W cm−2 and more than 5,900 hours of operation. Pd/C catalysts containing other heteroatoms (P, S, B) can also be improved through the addition of F atoms. Metal- and N-coordinated carbon materials are promising electrocatalysts, but improved activity and stability are desirable for fuel cell applications. Chang et al. address this by introducing F atoms into Pd/N–C catalysts, modifying the environment around the Pd and enhancing performance for ethanol oxidation and oxygen reduction.

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

Pt3Ni alloy structure is an effective strategy to accelerate ethanol oxidation reaction (EOR), while the stability in acid electrolyte is the fatal weakness and the current density still needs to be enhanced. Herein, ultralong Pt3Ni nanowires tailored by trace Mo (Mo/Pt3Ni NWs) were successfully synthesized by surfactant free method. The specific activity of the optimized catalyst was 2.66 mA·cm−2, which is approximately 2.16 and 4.6-fold that of Pt3Ni NWs and commercial Pt/C catalyst, respectively. Most importantly, the Mo/Pt3Ni NWs catalyst showed negligible structure degradation after 3,000 cycles (42 h) of durability test in 0.1 M HClO4 and 0.5 M ethanol, as compared to severe structural collapse and Ni dissolution for the pure Pt3Ni NWs. The density functional theory (DFT) calculation also confirmed that both the surface and subsurface Mo atom could form Pt-Mo and Ni-Mo bonds with Pt and Ni, which were stronger than Pt-Ni bonds, to pin the Ni atoms in the unstable position and suppress the dissolution of surface Ni. The findings of this study indicate a promising pathway for the design and engineering of durable alloy nanocatalysts for direct ethanol fuel cell applications.

In this work, the metal content of Pd85Ni10Bi5/C catalysts for the alkaline ethanol-oxidation reaction was reduced from 40 wt.% (PdNiBi/C (40/60)) to 30 wt.% (PdNiBi/C (30/70)), 20 wt.% (PdNiBi/C (20/80)) and 10 wt.% (PdNiBi/C (10/90)), while increasing performance. The synthesized catalysts were examined using physicochemical measurements and electrochemical measurements. The best performing catalysts were used to fabricate membrane electrode assemblies for carrying out single-cell tests and to determine the influence of the metal/carbon ratio of the electrode. The electrochemical surface area (695 cm2 mg−1) and activity were increased, resulting in high peak-current densities for the ethanol oxidation reaction (3.72 A mg−1) by the resulting more accessible metal particles. The electrode produced with the PdNiBi/C (30/70) catalyst reached a maximum power density of 34.8 mW mg−1 at 50 °C. This successfully demonstrated a doubling of the power density compared with the performance of the PdNiBi/C (40/60) electrode, while simultaneously reducing the costs.

Direct ethanol fuel cell (DEFC) as a promising device for converting chemical energy to electricity has been paid ever-increasing attention. However, the slow kinetics of ethanol electrooxidation at an anode hinders the application of DEFCs. Although Pt is the best catalyst among all the pure metal catalysts, it still has a relatively poor ability to break the C C bond, is deactivated by the accumulated COad intermediates, and undergoes unwanted desired structure change over long-term operation. In recent years, the addition of other metals to form binary, ternary, and quaternary catalysts have significantly improved electroactivity and stability. Ternary catalysts can have numerous element combinations and complicated architectures and, therefore, have been the subject of considerable research. In this review, most of the reported ternary catalysts will be summarized and categorized according to their structure while discussing the essence of the role of each component.

Made available in DSpace on 2022-04-29T08:32:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Multilayer graphene (G-US) and multilayer graphene muffled (Gm-US) produced by liquid exfoliation ultrasound were used as support for Pd nanoparticles with a load of 20 wt% for application in an alkaline direct ethanol fuel cell (ADEFC) anode. The multilayer graphene–based electrocatalyst (Pd/G-US) exhibited superior current density and less positive onset potential for ethanol oxidation reaction (EOR) than the commercial Pd/C (AA). Also, the Pd/G-US electrocatalyst showed the less positive onset potential for CO oxidation. In ADEFC experiments, the Pd/G-US catalyst exhibited a superior performance with 38 mW cm−2. The findings suggest that the defective graphene structure promotes electron transport, and the presence of oxygenated species increases hydrophilicity facilitating the oxidation of intermediates. Hence, the synthesized material can be considered as promising support for an anode in ADEFC. Graphical abstract: [Figure not available: see fulltext.] Laboratório de Eletroquímica e Materiais Nanoestruturados (LEMN) – Centro de Ciências Naturais e Humanas (CCNH) Universidade Federal Do ABC (UFABC), Rua Santa Adélia 166, Bairro Bangu Departamento de Química Instituto de Ciências Químicas E Farmacêuticas Universidade Federal de São Paulo (UNIFESP), Rua Prof. Artur Riedel 275, Jd. Eldorado Instituto Do Mar Universidade Federal de São Paulo (UNIFESP), Rua Carvalho de Mendonça, 144 Departamento de Físico-Química Instituto de Química de Araraquara Universidade Estadual Paulista (UNESP) Departamento de Físico-Química Instituto de Química de Araraquara Universidade Estadual Paulista (UNESP)

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.

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/CeZrO4/MCNT) were successively prepared to improve the activity of the ethanol oxidation reaction (EOR). The prepared CeZrO4 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 CeZrO4/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%CeZrO4/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.

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 CoNiO2 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, CoNiO2 and rGO, a significant enhancement in electrocatalytic behavior, stability and CO poisoning tolerance of PtPd have been observed. Regarding the implications, PtPd/CoNiO2/rGO is greatly preferable than Pt/CoNiO2/rGO and Pd/CoNiO2/rGO in terms of high electroactive surface area (ECSA), electro-catalytic activity, and lower onset potential (Eons) 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/CoNiO2/rGO nanocomposite is found to be an excellent anode electrocatalyst for application in DEFCs.

The performances of the core-shell nano-electrocatalysts (FeCo@Fe@Pd/CNT-OH and their monometallic Pd counterparts (Pd/CNT-OH) on carbon nanotubes in passive and active direct methanol fuel cells (DMFCs) and direct ethanol fuel cells (DEFCs) have been studied. The direct alcohol alkaline fuel cell (DAAFCs) performances of the two nanocatalysts studied revealed the outstanding performances of the core shell, FeCo@Fe@Pd catalysts over the single Pd metal on the same substrates. A fourfold increase in power density value was observed in the DEFC while a threefold increase was seen in the DMFC while operating both passive DAAFCs at moderate temperatures using the core shell nanocatalysts. The core-shell-modified electrode also gave an exceptional activity of over 50% columbic efficiency in comparison with its Pd counterpart in the passive DEFC. Density functional theory calculations carried out to further comprehend the electrocatalytic oxidation of the nanocatalysts towards both methanol and ethanol fuels corroborated the experimental findings. An increase in the readily available electrons of the partially filled d-orbitals was found to be involved in the catalytic reactions on the surface of the FeCo@Fe@Pd/CNT-OH core shell catalysts as opposed to those of the p-orbitals of Pd/CNT-OH, thus enhancing its catalytic activities in both DAAFCs.

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 Pd3–Ag1/C catalyst had superior catalytic activity (2911.98 mAmg−1Pd), 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.

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 HAuCl4 and PdCl2 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, Au8Pd3 NWs demonstrated the best electrocatalytic activity (mass activity 10,570 mA mg−1Pd) 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.

Direct ethanol fuel cells (DEFCs) are one of the resourceful and sustainable technologies for energy applications. Ethanol oxidation has been used to construct cost-effective and proficient electro...

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.

The development of advanced electrocatalysts for efficient catalyzing ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR) is significant for direct ethanol fuel cells (DEFCs). However, in many previous studies, the major difficulties including lower utilization efficiency and weaker anti-CO-poison ability of Pt hamper the practical testing of such DEFCs. Herein, ternary Pt22Pd27Cu51 ultrathin (~5 nm) NWs are fabricated via a facile surfactant-free strategy. The surface and electronic structures of Pt22Pd27Cu51 NWs are further tailored via acid-etching treatment. The resulted PtPdCu NWs with an optimal atomic Pt/Pd/Cu ratio of 36:41:23 display excellent specific activities towards EOR (4.38 mA/cm2) and ORR (1.16 mA/cm2), which are 19.8- and 5.7-folds larger than that of Pt/C, respectively. A single-cell was fabricated using Pt36Pd41Cu23 NWs as electrocatalyst in both anode and cathode with Pt loading of 1.2 mgPt/cm2. The power density measured at 80 °C is 21.7 mW/cm2, which is ~3.9 folds enhancement relative to that fabricated by using Pt/C (2 mgPt/cm2). The enhanced catalytic performance of Pt36Pd41Cu23 NWs could be attributed to that synergistic effect between Pt, Pd and Cu enhances CO anti-poisoning ability and promotes the C–C bond cleavage. This work provides a promising strategy for developing efficient electrocatalysts for DEFCs.

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.

The present investigation deals with Pd NPs casted over Fe2O3 support in formulating Pd/Fe2O3 catalyst with a complete non-Pt and non-carbon approach toward accomplishing the electrocatalysis of ethanol oxidation reaction (EOR) at the anode and oxygen reduction reaction (ORR) at the cathode in alkaline media for low-temperature fuel cell. The high electrochemical surface area (ECSA) for Pd/Fe2O3 with smart intervention of Fe2O3 directly/indirectly in EOR and ORR sequences makes this distinct catalyst a highly preferred choice in direct ethanol fuel cell with respect to reduced polarization loss, substantial current density output, and greater stability compared to the usual Pt or Pd nano-catalysts supported over carbon. Studies involved morphology, which was determined through electron microscopy and electrochemical characterization with the help of potentiodynamic polarization and RDE-RRDE techniques. The catalytic pre-eminence of the nanostructured Pd/Fe2O3 was manifested by the facile electrode kinetics at the anode and the cathode, low yield of H2O2 in ORR, and appreciable power density output of 36.01 mW cm−2 of the complete cell bearing enormous mass activity for both EOR and ORR. This novel attempt of introducing the same robust catalyst at both ends ensures better catalyst utilization, imparts affordability, and avoids carbon corrosion in the fuel cell environment.

s For the first time, reduced graphene oxide (RGO) and nitrogen doped RGO (N-RGO) are prepared by the electrochemical procedure and then decorates with palladium nanoparticles via a solvothermal method to obtain Pd/RGO and Pd/NRGO. The as-synthesized electrocatalysts are characterized by transition electron microscopy (TEM), x-ray photoelectron (XPS), energy dispersive spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR) techniques. The bare RGO and NRGO electrodes are very active for the oxygen reduction reaction (ORR) and ethanol tolerance, providing the best performance in terms of tafel slope and onset potential. But, the resulting Pd/NRGO electrocatalyst shows outstanding electrocatalytic performance toward both ORR and ethanol oxidation reaction (EOR), including higher peak current density and low tafel slope than that of Pd/RGO, which can be related to high electrochemical active surface area of Pd/NRGO (53 m2 g−1) than that of Pd/RGO (41 m2 g−1). Finally, the fabricated anionic alkaline Membrane-electrode assemblies (MEAs) by using RGO, NRGO, Pd/RGO and Pd/NRGO are studied in single air-breathing direct ethanol fuel cell, as anode and cathode, with solutions of 4 M ethanol and 2 M KOH at room temperature.

Direct Ethanol Fuel Cells (DEFCs) structures compose membrane that separate anode and cathode. Membrane is vital structure, that play an essential role in facilitating electrochemical reaction. The crucial characteristics of an excellent membrane to be applied in DEFCs should posses high ionic conductivity. However, current membrane in DEFCS relatively has lower ionic conductivity with a high price. Membrane conductivity is obtained from the measurement of resistivity of the proton-conductive membrane against the flow of current. Ionic conductivity measured by electrochemical impedance spectroscopy (EIS) using electrochemical system. In this study, the Anion Exchange Membrane (AEM) using Methyllcellulose as host was fabricated using simple casting solution technique with KOH as doping salt and Polyetylene glycol as plasticizer. The effects of weight variations of KOH and Polyethylene glycol (PEG) were investigated on conductivity measurements of membrane. The optimal ratio of AEM using MC, KOH and PEG was performed via Central Composite Design (CCD) experiment. Based on the hierarchical agglomerative cluster analysis (HACA) approach, the results are grouped into their own clusters which shows the most reliable results. The optimum weight of plasticizers recorded is 1.5 g, 0.55 g, and 1.0 g for MC, KOH and PEG respectively yield the maximum conductivity which is 0.00025305 S/m. In summary, the findings of proper ratio weight of each compound are crucial to enhance the conductivity value.

Development of bifunctional catalysts with low platinum (Pt) content for the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR) is highly desirable, yet challenging. Herein, we present structural engineering of a series of two-dimensional/three-dimensional (2D/3D) hierarchical N-doped graphene-supported nanosized Pt

Made available in DSpace on 2020-12-12T02:42:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) In this work electrocatalysts based on Pd and Sn nanoparticles supported on Vulcan XC-72 carbon black with a reduced amount of Pd were prepared. We evaluated its electrocatalytic activity for ethanol oxidation reaction (EOR) in alkaline direct ethanol fuel cells (ADEFCs). The electrocatalysts were synthesized in different Pd:Sn mass ratios (1:3, 1:1, 3:1 and 1:0) on the carbon containing 20 wt % of metal. The XRD patterns of the electrocatalysts revealed an alloy formation between Pd and Sn, and the electrocatalysts with lowest amount of Pd (Pd1Sn3/Vulcan XC-72) and highest electrochemically active surface area (ECSA) presented best performance in ADEFC experiments with a maximum current density and power density of 152 mA cm-2 and 42 mW cm-2, respectively. Besides the current density three times higher for EOR than that of the pure Pd, the open circuit potential of 939 mV at an operation temperature of 80 °C yielded the higher carbonate production. This behavior can be attributed to the presence of oxophilic Sn species, which improve the ability to remove adsorbed CO. Oxygenated species, vacancies and defects detected in the structure of PdxSny/Vulcan XC-72 catalysts are accounted for their high activity, making them very promising for the application in ADEFC. Laboratório de Eletroquímica e Materiais Nanoestruturados (LEMN) - Centro de Ciências Naturais e Humanas (CCNH) Universidade Federal do ABC (UFABC), Rua Santa Adélia 166, Bairro Bangu Instituto Federal de Educação Ciência e Tecnologia do Maranhão (IFMA) Campus Açailândia, R. Projetada, s/n Instituto de Química UNESP Universidade Estadual Paulista Instituto de Química UNESP Universidade Estadual Paulista FAPESP: 2015/10314-8 FAPESP: 2017/00819-8 FAPESP: 2017/10118-0 FAPESP: 2017/21846-6 FAPESP: 2017/22976-0 FAPESP: 2017/26288-1 FAPESP: 2018/26307-9 CNPq: 406612/2013-7

Electrocatalyst support materials play significant role in the performance, durability and commercialization of fuel cells. This research work describes the preparation of metal oxide (nickel oxide (NiO), cobalt (Co) and copper (Cu) doped NiO) support materials on meshed titanium (Ti) substrate via a simple electro-deposition method for their application as novel support material for palladium (Pd) catalyst. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) techniques are employed to study morphology, composition and structure of fabricated electrodes, respectively. The electrocatalytic performance of fabricated electrodes toward ethanol oxidation reaction (EOR) in alkaline solution is examined by the cyclic voltammetry (CV), chronoamperometry (CA) techniques. Low peak potential (−0.2 V), increased peak current density (62.54 mA cm−2) and large electrochemical active surface area (16.02 m2 g−1) were remarkable properties of Pd/Cu–NiO/Ti electrode. The results of other electrochemical measurements, CO-striping voltammetry, long-term stability and electrochemical impedance spectroscopy (EIS) revealed that the Pd/Cu–NiO/Ti electrode has the privileged electrocatalytic performance for EOR relative to other prepared electrodes. Accordingly, the Pd/Cu–NiO/Ti can be considered as a hopeful electrode for ethanol electro-oxidation reaction in DEFCs.

The catalysis of Au thin film could be improved by fabrication of array structures in large area. In this work, nanoimprint lithography has been developed to fabricate flexible Au micro-array (MA) electrodes with ∼ 100% coverage. Advanced electron microscopy characterisations have directly visualised the atomic-scale three-dimensional (3D) nanostructures with a maximum depth of 6 atomic layers. In-situ observation unveils the crystal growth in the form of twinning. High double layer capacitance brings about large number of active sites on the Au thin film and has a logarithmic relationship with mesh grade. Electrochemistry testing shows that the Au MAs perform much better ethanol oxidation reaction than the planar sample; MAs with higher mesh grade have a greater active site utilisation ratio (ASUR), which is important to build electrochemical double layer for efficient charge transfer. Further improvement on ASUR is expected for greater electrocatalytic performance and potential application in direct ethanol fuel cell.[Figure not available: see fulltext.]. Ministry of Education (MOE) This research was supported by the MOE AcRF Tier 1 grant M4011528. The XRD and FEG-TEM characterisations were performed at Facility for Analysis, Characterisation, Testing and Simulation (FACTS) Lab; the FEG-SEM/FIB characterisations were carried out at Microelectronics Reliability and Characterisation (MRC) Lab.

The conventional anode design of direct ethanol fuel cells (DEFCs) usually encounter a problem on the performance stability and ethanol mass transport, i.e., ethanol crossover. Aiming to alleviate these issues, in this study, the anode with different configurations for DEFC was designed and fabricated with different catalyst layer (CL) and microporous layer (MPL) arrangements. The four types of membrane electrode assembly (MEA) is named with MEA-1 (with pretreated carbon paper (PCP) and PtCL), MEA-2 (with PCP, MPL and PtCL), MEA-3 (with PCP, MPL, PtCL and PdCL) and MEA-4 (with PCP, MPL, PtCL, MPL and PdCL). The performance, stability and ethanol crossover of MEAs were tested and measured for continuous long-term operation for 120 h, while the morphological characterization was analyzed. Based on the results, power density for each MEA decreased with time, while ethanol crossover increased gradually. The MEA-3 with additional PdCL shows a highest performance and stability about 20 W/m2, and has a lowest ethanol crossover's magnitude. The highest ethanol crossover was obtained using MEA-1 at 3.7 mg/m2·s. Higher ethanol crossover had caused low stability of DEFC performance which result higher irreversible degradation. Moreover, based on characterization, elemental mapping and EDX illustrated phenomena of membrane swelling, delamination of electrode from membrane, and CL loss after stability test for 5 days for all MEAs. The significance of anode structure design was proven in this current study. The anode design of double-layered CL has potential to use at anode structure to reduce ethanol crossover rate, thereby improving DEFC performance and stability.

Nickel foam has been applying as the electrode support material for alkaline direct ethanol fuel cells, since its unique three-dimensional network structure helps efficiently use the catalyst to improve the cell performance. In this work, the effect of the thickness of nickel foam electrodes on cell performance is investigated. The experimental results show that the nickel foam thickness influences both the electron conduction and mass transfer, and the optimal thickness is a trade-off between them. Through XRD, SEM image, polarization curve test, EIS test and CV test, it is found that the nickel foam electrode with the thickness of 0.6 mm has better performance than that of 0.3 mm and 1.0 mm. The thinner the nickel foam, the better the conductivity. However, the corresponding three-dimensional space becomes narrower, which leads to partial agglomeration of the catalyst and hindrance of mass transfer. In addition, the influence of catalyst loading on the performance of 0.6 mm nickel foam electrode is explored. The maximum power density of 1.0 mg cm−2 Pd loading reaches 56.3 mW cm−2 at 60 °C, which is higher than that of 2.0 mg cm−2 loading, indicating that the three-dimensional network structure of nickel foam can efficiently utilize the catalyst, and fully exert the catalytic function of the catalyst even at a lower catalyst loading. Moreover, the effects of operating temperature and ethanol concentration on cell performance are also studied. The cell performance increases with the increase of temperature, and it reaches the highest with 3 M ethanol.

Direct ethanol fuel cells (DEFCs) are considered as the ideal green power suppliers because of high energy density and non-toxicity of ethanol. Here the ball cactus-like gold (Au) particles reduced by hydrogen peroxide solution are coated with sulfhydryl-functionalized carbon dots (SCDs-Au). When the SCDs-Au composite is employed as the anodic electrocatalyst for ethanol oxidation reaction, an anode peak current density of 23.23 mA cm−2 (mass activity of 102.65 mA mg−1) is obtained at 0.19 V (vs. SCE) in 1.0 M KOH and 1.0 M ethanol at a scan rate of 20 mV s−1, which is about 4.4 times than that of Au without modification of SCDs. The higher catalytic activity is attributed to the higher ethanol adsorption capability caused by the shell-like SCDs. According to the adsorption experiment, ethanol adsorption capability of SCDs-Au is calculated as 2.8 times than that of Au without modification. At the same time, the addition of SCDs improves the electrocatalytic stability of Au. Such a surface modification method can be applied in other catalyst design processes. The ball cactus-like gold (Au) particles reduced by hydrogen peroxide solution are coated with sulfhydryl-functionalized carbon dots (SCDs-Au). SCDs-Au shows enhanced anode current density for ethanol oxidation attributed to the higher ethanol adsorption capability caused by CDs shell.

The anodic reaction in direct ethanol fuel cells (DEFCs), ethanol oxidation reaction (EOR) faces challenges, such as incomplete electrooxidation of ethanol and high cost of the most efficient electrocatalyst, Pt in acidic media at low temperature. In this study, core-shell electrocatalysts with an Au core and Pt-based shell (Au@Pt) are developed. The Au core size and Pt shell thickness play an important role in the EOR activity. The Au size of 2.8 nm and one layer of Pt provide the most optimized performance, having 6 times higher peak current density in contrast to commercial Pt/C. SnO2 as a support also enhances the EOR activity of Au@Pt by 1.73 times. Further modifying the Pt shell with Ru atoms achieve the highest EOR current density that is 15 and 2.5 times of Pt/C and Au@Pt. Our results suggest the importance of surface modification in rational design of advanced electrocatalysts.

The ethanol oxidation reaction is of critical importance to the commercial viability of direct ethanol fuel cell technology. However, owing to the poor C-C bond cleavage capability, almost all ethanol oxidation is incomplete and suffers from low selectivity toward the C1 pathway. Herein, under the support of theoretical calculations that the heterointerfaces between CoP and Pd can reduce the energy barrier of C-C bond cleavage, rich heterointerfaces in CoP/RGO-Pd hybrids were designed to improve ethanol electrooxidation performance through enhancing the selectivity toward the C1 pathway. The experimental results show that the faradaic efficiency of the C1 pathway of CoP/RGO-Pd hybrids is as high as 27.6%, surpassing most reported catalysts in the literature. As a result of this enhancement, CoP/RGO-Pd10 exhibits mass activity as high as 4597 mA·mg

The development of highly efficient Pt-based nanocatalysts is important for the commercialization of direct ethanol fuel cells (DEFCs) but remains challenging to achieve. Here in, we developed an ingenious strategy to significantly improve the electrocatalytic property of Pt-based catalyst towards ethanol oxidation reactions (EOR) in acid medium by doping tungsten. In this study carbon (Vulcan XC-72R, Ketjen black, carbon nanotubes) supported Pt-surface-enriched platinum–tungsten bimetallic nanoparticles (W@Pt/C, W@Pt/KJ, W@Pt/CNT) were prepared using the etching effect of galvanic replacement on amorphous tungsten nanoparticles. Additionally, no surfactant is used in the preparation of the catalysts. The catalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. From the results, we can conclude that W@Pt nanoparticles were uniformly loaded on each carbon support. Finally, when compared with JM Pt/C, the catalytic activity of W@Pt/C was increased by 30% and the current density retained by W@Pt/C was 1.6 times that of the commercial catalyst (123 mA mgPt−1). At the end of the 3600 s reaction, W@Pt/C retained a current density of 198 mA mg−1 which is 1.6 times that of commercial catalyst JM Pt/C (123 mA mg−1). Also, W@Pt/KJ retained a current density of 176 mA mg−1 which is 1.4 times that of JM Pt/C. Furthermore, the metal oxides (WOX) in the catalyst can easily adsorb -OH species which can transform COads poisoning species to CO2, thus promoting the catalytic activity and stability toward EORs.

Pt-Ru and Pt–Re and Pt-Ru-Re nanoparticles supported on functionalized multi-walled carbon nanotubes (f-MWCNT) were synthesized via modified polyol reduction method and tested thoroughly in a half cell and single direct ethanol fuel cell for ethanol electrooxidation in acidic medium. The MWCNTs were functionalized in a mixture of HNO3/H2SO4 solution for depositing a more active metal alloy nanoparticle on support material. The alloy formation of bi-metallic and tri-metallic electrocatalysts were examined by XRD analysis and more clearly explained by FE-SEM element mapping. The TEM analyses reveal that electrocatalysts nanoparticles are well dispersed on f-MWCNT, with spherical shapes and nano sizes range of 1.5–4 nm. The electrochemical analyses by cyclic voltammetry and chronoamperometry measurements reveal that tri-metallic electrocatalyst Pt-Ru-Re (1:1:0.5)/f-MWCNT exhibits the highest electrocatalytic activity and stability towards ethanol electrooxidation among all the synthesized electrocatalysts. The same electrocatalyst as anode in single DEFC results in excellent performance in comparison to all other synthesized electrocatalysts, with a maximum power density of 9.52 mW/cm2 at a cell temperature of 30 °C. The bi-metallic Pt-Ru (1:1)/f-MWCNT and Pt–Re (1:1)/f-MWCNT produced power density of 7.48 mW/cm2 and 4.74 mW/cm2 at room temperature of 30 °C. The power density of DEFC enhanced 2.44 times, when cell operating temperature was increased from 30 °C to 80 °C using anode electrocatalyst Pt-Ru-Re (1:1:0.5)/f-MWCNT and keeping other parameters constant. The best result obtained in half cell and single DEFC using Pt-Ru-Re (1:1:0.5)/f-MWCNT electrocatalyst may be attributed to the synergistic effect of Pt, Ru and Re combined with bi-functional and ligand effects.

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

Direct ethanol fuel cell (DEFC) has received tremendous research interests because of the more convenient storage and transportation of ethanol vs. compressed hydrogen. However, the electrocatalytic ethanol oxidation reaction typically requires precious metal catalysts and is plagued with relatively high over potential and low mass activity. Here we report the synthesis of Pt3Ag alloy wavy nanowires via a particle attachment mechanism in a facile solvothermal process. Transmission microscopy studies and elemental analyses show highly wavy nanowire structures with an average diameter of 4.6 ± 1.0 nm and uniform Pt3Ag alloy formation. Electrocatalytic studies demonstrate that the resulting alloy nanowires can function as highly effective electrocatalysts for ethanol oxidation reactions (EOR) with ultrahigh specific activity of 28.0 mA/cm2 and mass activity of 6.1 A/mg, far exceeding that of the commercial Pt/carbon samples (1.10 A/mg). The improved electrocatalytic activity may be partly attributed to partial electron transfer from Ag to Pt in the Pt3Ag alloy, which weakens CO binding and the CO poisoning effect. The one-dimensional nanowire morphology also contributes to favorable charge transport properties that are critical for extracting charge from catalytic active sites to external circuits. The chronoamperometry studies demonstrate considerably improved stability for long term operation compared with the commercial Pt/C samples, making the Pt3Ag wavy nanowires an attractive electrocatalyst for EOR.

Platinum (Pt) is widely used as anode catalyst for direct ethanol fuel cell (DEFC) but toxic CO gas was produced in the system. Pt bimetallic catalysts can increase the reaction rate, current density and reduce CO gas production. However, some bimetallic catalysts are still expensive and give the low reaction rate. Trimetallic catalysts on carbon supporter were represented instead due to their better catalytic activities, long life time of operation and higher current density. In this study, we synthesized trimetallic alloy on N-doped reduced graphene oxide (NrGO) catalysts using as DEFC anode. The percentage of metals composition in the synthesized catalysts was varied. NrGO was prepared by Modified Hummers Method, then reduced by annealing under Nitrogen gas atmosphere and N-added by annealing with melamine. The preparation method for trimetallic alloy catalysts on NrGO was NaBH4 reduction. The X-ray diffraction (XRD) patterns displayed their alloy phase of PtMRu (M = Au, Sn) which compose of Pt main structure and NrGO supporter. Scanning Electron Microscopy (SEM) images showed the dispersion of alloy metal particles on NrGO surface. The composition of catalysts could be confirmed by Energy dispersive spectroscopy (EDS) data and the phase of alloy particles were verified by electron diffraction (SAD) patterns. Transmission Electron Microscopy (TEM) images showed the particle size of PtAuRu and PtSnRu in various specific percentage on NrGO. The approximate particle size for 10Pt2Au8Ru = 4.88±1.02 nm, 10Pt5Au5Ru = 58.45±42.16 nm, 10Pt8Au2Ru = 11.05±2.29 nm, 10Pt2Sn8Ru = 3.31±1.44 nm, 10Pt5Sn5Ru = 3.50±0.73 nm and 10Pt8Sn2Ru = 4.09±0.97 nm. Catalytic activity of these materials related to their particle size.

The electrocatalytic performance of Polypyrrole-Copper oxide particles modified carbon paste electrode (Cu2O/PPy/CPE) for electrocatalytic oxidation of ethanol was reported for the first time in alkaline media. The composite Cu2O/PPy was prepared using a facile approach consisting on the deposition of Polypyrrole film on CPE using galvanostatic mode then followed by the deposition of Copper particles at a constant potential. Scanning electron spectroscopy (SEM), infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the structural and electrochemical properties of the Cu2O/PPy/CPE and to explain the mechanism of electrooxidation of ethanol. The experimental parameters that influence the electrooxidation of ethanol were investigated and optimized. Our findings suggest that the electrodeposition of Copper particles on Polypyrrole film enhanced the catalytic activity towards the ethanol oxidation with a peak current density of 2.25 mA cm−2 at 0.8 V vs Ag/AgCl, which is 2.6 times higher than the peak current density obtained by PPy/CPE electrode. It important to note that the saturation limit reaches a value of 5 M. To summarize, the good catalytic activity, stability and easy preparation make the Cu2O/PPy composite as an excellent electrocatalyst for ethanol oxidation.

The design of electrocatalysts with high activity and enhanced durability for the ethanol oxidation reaction (EOR) is critical for commercializing direct ethanol fuel cells (DEFCs). Herein, a disti...

A highly electroactive nickel nanorod (NNR)/nickel foam (NF) electrode was fabricated for direct alcohol fuel cells (DAFCs) using a simple and cost-effective hydrothermal process. The Ni/NiO nanorods were successfully grown on the surface of an NF electrode, which strongly enhanced the anode wettability and increased surface area by 18 times (11.9 m2 g−1), resulting in interfacial polarization resistance reduction. The NNR/NF electrode shows high electro-catalytic activity and great stability during alcohol oxidation. The current densities obtained for NNR/NF were four (479 mA cm−2) and six (543 mA cm−2) times higher than that for pristine NF in the cases of methanol and ethanol oxidations, respectively. This high current density can be attributed to the superhydrophilic surface of the Ni/NiO nanorods and corresponding high mass transfer capability between the electrolytes and Ni/NiO nanorods embedded on the surface of the electrodes. This study presents a new approach for using the novel NNR/NF as a cheap and high performance anode in DAFCs.

Direct ethanol fuel cells (DEFCs) have shown a high potential to supply energy and contribute to saving the climate due to their bioethanol sustainability and carbon neutrality. Nonetheless, there is a consistent need to develop new catalyst electrodes that are active for the ethanol oxidation reaction (EOR). In this work, two C-supported PdIrNi catalysts, that have been reported only once, are prepared via a facile NaBH4 co-reduction route. Their physiochemical characterization (X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS)) results show alloyed PdIrNi nanoparticles that are well dispersed (&lt, 3 nm) and exist in metallic state that is air-stable apart from Ni and, slightly, Pd. Their electrocatalytic activity towards EOR was evaluated by means of cyclic voltammetry (CV) and chronoamperometry (CA). Even though the physiochemical characterization of PdIrNi/C and Pd4Ir2Ni1/C is promising, their EOR performance has proven them less active than their Pd/C counterpart. Although the oxidation current peak of Pd/C is 1.8 A/mgPd, it is only 0.48 A/mgPd for Pd4Ir2Ni1/C and 0.52 A/mgPd for PdIrNi/C. These results were obtained three times and are reproducible, but since they do not add up with the sound PdIrNi microstructure, more advanced and in situ EOR studies are necessary to better understand the poor EOR performance.

A method for preparing polybenzimidazole or polybenzimidazole blend membranes and fabricating gas diffusion electrodes and membrane-electrode assemblies is provided for a high temperature polymer electrolyte membrane fuel cell. Blend polymer electrolyte membranes based on PBI and various thermoplastic polymers for high temperature polymer electrolyte fuel cells have also been developed. Miscible blends are used for solution casting of polymer membranes (solid electrolytes). High conductivity and enhanced mechanical strength were obtained for the blend polymer solid electrolytes. With the thermally resistant polymer, e.g., polybenzimidazole or a mixture of polybenzimidazole and other thermoplastics as binder, the carbon-supported noble metal catalyst is tape-cast onto a hydrophobic supporting substrate. When doped with an acid mixture, electrodes are assembled with an acid doped solid electrolyte membrane by hot-press. The fuel cell can operate at temperatures up to at least 200 °C with hydrogen-rich fuel containing high ratios of carbon monoxide such as 3 vol% carbon monoxide or more, compared to the carbon monoxide tolerance of 10-20 ppm level for Nafion®-based polymer electrolyte fuel cells.

Direct methanol fuel cells (DMFCs) and direct ethanol fuel cells (DEFCs) have drawn great attention as promising power sources for mobile and portable devices. However, the anodic reactions in DMFCs and DEFCs, namely the methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR), suffer from notoriously sluggish kinetics which seriously limited their large-scale applications. In this review, we will present a brief review on the interfacial engineering of noble metals for the MOR and EOR. This review starts by introducing the fundamental electrochemistry of the MOR and EOR and the performance evaluation of MOR and EOR electrocatalysts. We then move to summarize recent advances in the design and synthesis of MOR and EOR electrocatalysts in acidic and alkaline electrolytes, in which we emphasize the importance of rational engineering of the interface in noble metals (such as Pt, Pd and Rh) for enhanced activity and improved stability toward the MOR and EOR. Finally, challenges and prospects will be concluded for designing better MOR and EOR electrocatalysts.

In direct ethanol fuel cell technology, the sluggish kinetics of the ethanol oxidation reaction (EOR) at the anode is the main obstacle, and it is thus urgent to develop high performance catalysts. In this work, a new class of porous Ir3Pb nanodendrites (NDs) was successfully synthesized. The specific activity and mass activity of the synthesized ND-Ir3Pb/C reach 1.337 mA cm−2 and 801.1 mA mgIr−1, respectively, which are 5.79 and 5.82 times higher than those of the commercial Pt/C-JM. Moreover, the much higher CO2 selectivity and enhanced durability of ND-Ir3Pb/C were also evaluated compared to those of the commercial Pt/C-JM. Unexpectedly, we found that the EOR performance, especially the durability and CO2 selectivity of ND-Ir3Pb/C can be enhanced dramatically by alloying trace Au (Ir : Au = 3 : 0.05). The specific activity loss of ND-Ir3PbAu0.05/C was only 13.9% after 6000 potential cycles, which is much smaller than that of ND-Ir3Pb/C (34.3%) and Pt/C-JM (53.7%). This study provides a strategic design of efficient Ir-based EOR catalysts for fuel cells.

The wide application of direct ethanol fuel cells (DEFCs) was blocked by the sluggish catalytic activity of catalysts, insufficient ionic conductivity of the polymer electrolyte membrane (PEM), and ethanol crossover issues. To overcome the problems mentioned above, a novel DEFC system with a polymer fiber membrane (PFM) and nonplatinum catalysts is proposed. In this system, the performance of the anode catalyst Pd/C is significantly promoted by homogeneous Ni-doped SnO2 nanoparticles, and the inexpensive permeable PFM is used as a substitute for the PEM. Due to the remarkable catalytic activity and the optimized resistance, the PFM-based DEFC exhibits encouraging performance, which can afford a peak power density of 47.4 mW cm−2 with a porous NiCo2O4 cathode catalyst. Moreover, it can operate continuously for 100 h with only 4.56% drop in electrical output. Therefore, this study provides a very effective strategy for optimizing DEFCs with low cost and high performance.

High-quality Pt-based catalysts are highly desirable for ethanol oxidation reaction (EOR), which is of critical importance for the commercial applications of direct ethanol fuel cells (DEFCs). However, most of the Pt-based catalysts have suffered from high cost and low operation durability. Herein a two-step method has been developed to synthesize porous Pt nanoframes decorated with Bi(OH)3, which show excellent catalytic activity and operation durability in both alkaline and acidic media. For example, the nanoframes show a mass activity of 6.87 A·mgPt−1 in alkaline media, which is 13.5-fold higher than that of commercial Pt/C. More importantly, the catalyst can be reactivated simply, which shows negligible activity loss after running for 180,000 s. Further in situ attenuated total reflection-infrared (ATR-IR) absorption spectroscopy and CO-stripping experiments indicate that surface Bi(OH)3 species can greatly facilitate the formation of adsorbed OH species and subsequently remove carbonaceous poison, resulting in a significantly enhanced stability towards EOR. This work may favor the tailoring of desired electrocatalysts with high activity and durability for future commercial application of DEFCs.

Highly dispersed Pt-Ru nano electrocatalysts supported on functionalized acetylene black carbon (CAB) were synthesized by a modified polyol reduction route followed by post treatment under three different conditions. The synthesized Pt-Ru/CAB-syn electrocatalysts after post treatment were designated as Pt-Ru/CAB-H2-RT when treated under H2 atmosphere at room temperature of 40 °C, and Pt-Ru/CAB-H2-160 when treated under H2 atmosphere at 160 °C and Pt-Ru/CAB-Air-160 when treated under air at 160 °C, respectively. The post treatment of synthesized electrocatalyst modified the crystallographic and morphological structures of the synthesized electrocatalysts which enhanced the electrocatalytic activity for ethanol electrooxidation. The physical characteristics of the post-treated electrocatalysts were recorded using XRD, SEM-EDX and TEM techniques. The XRD and TEM analyses revealed that the synthesized electrocatalysts have particle size in nano range with narrow size distribution. The electrochemical study of synthesized electrocatalysts were evaluated via cyclic voltammetry and chronoamperometry revealed that the Pt-Ru/CAB-H2-RT electrocatalyst is the most active exhibit towards ethanol electrooxidation in comparison to that of Pt-Ru/CAB-H2-160, Pt-Ru/CAB-Air-160 and commercial Pt-Ru/C electrocatalysts. In DEFC performance test at a temperature of 40 °C, the obtained power density (9.15 mW/cm2) using the synthesized Pt-Ru/CAB-H2-RT as anode electrocatalyst was higher than that of Pt-Ru/CAB-Air-160 (5.79 mW/cm2), Pt-Ru/CAB-H2-160 (6.84 mW/cm2) and commercial Pt-Ru/C (7.86 mW/cm2) electrocatalysts with same anode electrocatalyst loading of 1 mg/cm2 and 2 M ethanol fuel. The maximum OCV of 0.737 V and power density of 16.23 mW/cm2 at 0.317 V with a current density of 51.2 mA/cm2 were obtained using Pt-Ru/CAB-H2-RT electrocatalyst as anode at a cell temperature of 80 °C. The enhanced and superior performance of Pt-Ru/CAB-H2-RT electrocatalyst after post treatment could be attributed to well alloyed microstructure and highly dispersed surface morphology of metal nanoparticles.

PtRh/C–ITO electrocatalysts were prepared in a single-step method using H2PtCl6·6H2O and RhCl3·xH2O as metal sources, sodium borohydride as the reducing agent and a physical mixture of 85% Vulcan Carbon XC72 and 15% In2O3·SnO2 (indium tin oxide—ITO) as support. PtRh/C–ITO were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry, chronoamperommetry, attenuated total reflectance, Fourier transform infrared spectroscopy and performance test on direct alkaline ethanol fuel cell. X-ray diffraction patterns for all PtRh/C–ITO indicated a shift in Pt (fcc) peaks, showing that Rh was incorporated into Pt lattice. Transmission electron microscopy for PtRh/C–ITO showed nanoparticles homogeneously distributed over the support with particles size between 3.0 and 4.0 nm. The XPS results for Pt70Rh30/C–ITO showed the presence of mixed oxidation states of Sn0 and SnO2 that could favor the oxidation of adsorbed intermediates by bifunctional mechanism. Pt90Rh10/C–ITO was more active in electrochemical studies, which could be associated with the C–C bond break. Experiments in direct alkaline ethanol fuel cells showed that the power density values obtained for Pt70Rh30/C–ITO and Pt90Rh10/C–ITO were higher than Pt/C, indicating the beneficial effect of Rh addition to Pt and the use of C–ITO support.