An alkaline direct ethylene glycol fuel cell with an alkali-doped polybenzimidazole membrane

An alkaline direct ethylene glycol fuel cell (DEGFC) with an alkali-doped polybenzimidazole membrane (APM) is developed and tested. It is demonstrated that the use of APMs enables the present fuel cell to operate at high temperatures. The fuel cell results in the peak power densities of 80 mW cm⁻² at 60 °C and 112 mW cm⁻² at 90 °C, respectively. The power output at 60 °C is found to be 67% higher than that by DEGFCs with proton exchange membranes, which is mainly attributed to the superior electrochemical kinetics of both ethylene glycol oxidation and oxygen reduction reactions in alkaline media.     

Performance of a direct ethylene glycol fuel cell with an anion-exchange membrane

This paper reports on the development and performance test of an alkaline direct ethylene glycol fuel cell. The fuel cell consists of an anion-exchange membrane with non-platinum electrocatalysts at both the anode and cathode. It is demonstrated that this type of fuel cell with relatively cheap membranes and catalysts can result in a maximum power density of 67 mW cm⁻² at 60 °C, which represents the highest performance that has so far been reported in the open literature. The high performance is mainly attributed to the increased kinetics of both the ethylene glycol oxidation reaction and oxygen reduction reaction rendered by the alkaline medium with the anion-exchange membrane.     

Performance of a hybrid direct ethylene glycol fuel cell

In this work, a hybrid fuel cell is developed and tested, which is composed of an alkaline anode, an acid cathode, and a cation exchange membrane. In this fuel cell, ethylene glycol and hydrogen peroxide serve as fuel and oxidant, respectively. Theoretically, this fuel cell exhibits a theoretical voltage reaching 2.47 V, whereas it is experimentally demonstrated that the hybrid fuel cell delivers an open‐circuit voltage of 1.41 V at 60°C. More impressively, this fuel cell yields a peak power density of 80.9 mW cm^?2 (115.3 mW cm^?2 at 80°C). Comparing to an open‐circuit voltage of 0.86 V and a peak power density of 67 mW cm^?2 previously achieved by a direct ethylene glycol fuel cell operating with oxygen, this hybrid direct ethylene glycol fuel cell boosts the open‐circuit voltage by 62.1% and the peak power density by 20.8%. This significant improvement is mainly attributed not only to the high‐voltage output of this hybrid system design but also to the faster kinetics rendered by the reduction reaction of hydrogen peroxide.     

Study of core-shell platinum-based catalyst for methanol and ethylene glycol oxidation

A Ru_core-Pt_shell, XC72-supported catalyst was synthesized in a two-step process: first, by deposition of Ru on XC72 by the polyol process and then by deposition of Pt on the XC72-supported Ru, with NaBH₄ as reducing agent. The structure and composition of this core-shell catalyst were determined by EDS, XPS, TEM and XRD. Electrochemical characterization was determined with the use of cyclic voltammetry and chronoamperometry. The methanol and ethylene glycol oxidation activities of the core-shell catalyst were studied at 80 °C and compared to those of a commercial catalyst. It was found to be significantly better (in terms of A g⁻¹ of Pt) in the case of methanol oxidation and worse in the case of ethylene glycol oxidation. Possible reasons for the lower ethylene glycol oxidation activity of the core-shell catalyst are discussed.     

Effect of methanol, ethylene glycol and their oxidation by-products on the activity of Pt-based oxygen-reduction catalysts

Direct-oxidation fuel cells (DOFC) are promising electrochemical devices for various applications. In addition to methanol (MeOH), alternative fuels are being tested in a search for lower toxicity, safer handling, and higher energy density. Ethylene glycol (EG) was employed as one of such fuels. However, DOFCs face several problems, such as fuel crossover through the membrane during its operation. This not only lowers the cell potential but also poisons the catalyst for the oxygen-reduction reaction (ORR). Experiments were performed on the poisoning of Pt and Pt-alloy ORR catalysts (both commercial and homemade, by electroless deposition), by fuels and their oxidation by-products. At 25 °C, methanol poisoning was found to be reversible and the catalytic activity measured afterwards in a fuel-free solution and the electrochemical surface area (ECSA) were enhanced. The effect of poisoning by methanol and ethylene glycol and their oxidation intermediates is reported here for the first time. The severity of poisoning was found to be MeOH ? formaldehyde < formic acid. In solutions of EG and its oxidation by-products, the poisoning order was EG ≤ glycolic acid < oxalic acid, the poisoning of all three being more severe than that of methanol. The catalysts most resistant both to MeOH and EG poisoning were commercial acid-treated PtCo and homemade PtCoSn. The reasons for the enhanced tolerance were investigated and PtCoSn was found to be the less active both in the methanol and ethylene glycol oxidation processes.     

A poly(ethylene glycol)-based smart phase change material

A shape memory thermoplastic polyurethane (PU) as a phase change material (PCM) was synthesized by employing poly(ethylene glycol) (PEG) as the soft segment via bulk polymerization. Its phase separation structure, crystalline morphology, phase change behaviors, dynamic mechanical properties and melt-processing ability were investigated using polarizing optical microscopy, atomic force microscopy, differential scanning calorimetry, dynamic mechanical analysis, thermogravimetry and melt flow index. A well-formed phase separation structure in the PEG-based polyurethane (PEGPU) was found which accounts for most of the material phase change properties and shape memory effect. The PEG soft segment phase transition between crystalline and amorphous states resulted in heat storage and release of the PEGPU. Due to the hydrogen bonded hard segment phase serving as “physical cross-linking” restricted the free movement of the soft segments, at temperature above the PEG phase melting transition, the PEGPU was still solid. The differential scanning calorimetry results indicated that the PEGPU had high latent heat storage capacity of more than 100 J/g. The dynamic mechanical analysis results showed that it had a plateau elastic modulus about 40 MPa in the region above the PEG phase melting transition while below 150 °C. The thermogravimetry results suggested that the PEGPU had a much broader applicable temperature range compared with pure PEG. The melt flow index results indicated that the material had a good melt-processing ability. The material shape fixity ratio was more than 84% and shape recovery ratio up to 93.7% obtained from thermomechanical cyclic tensile testing.     

Comparison of methanol and ethylene glycol oxidation by alloy and Core-Shell platinum based catalysts

Two Core-Shell, Ru_Core-Pt_Shell and IrNi_Core-PtRu_Shell, XC72-supported catalyst were synthesized in a two-step deposition process with NaBH₄ as reducing agent. The structure and composition of the Core-Shell catalysts were determined by EDS, XPS and XRD. Electrochemical characterization was performed with the use of cyclic voltammetry. Methanol and ethylene glycol oxidation activities of the Core-Shell catalysts (in terms of surface and mass activities) were studied at 80 °C and compared to those of a commercial Pt-Ru alloy catalyst. The surface activity of the alloy based catalyst, in the case of methanol oxidation, was found to be superior as a result of optimized surface Pt:Ru composition. However, the mass activity of the PtRu/IrNi/XC72 was higher than that of the alloy based catalyst by ∼50%. Regarding ethylene glycol oxidation, while the surface activity of the alloy based catalyst was slightly higher than that of the Pt/Ru/XC72 catalyst, the latter showed ∼66% higher activities in terms of A g⁻¹ of Pt. These results show the potential of Core-Shell catalysts for reducing the cost of catalysts for DMFC and DEGFC.     

Preparation of NiO nanofibers by electrospinning and their application for electro-catalytic oxidation of ethylene glycol

In this work, nickel oxide nanofibers (NiO-NFs) are produced by electrospinning method and calcination in air for 5 h. The thermal gravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and electrochemical impedance spectroscopy (EIS) are used for characterization of the NiO-NFs. The FE-SEM images of the precursor indicate that a large quantity of nanofibers with diameters ranging from 100 to 150 nm with tens of micrometers in length can be acquired. Also, the results show that rough NiO-NFs having large specific surface area are composed of the small nanoparticles. After calcination, the nanofibers are composed of cubic structure. The EIS study shows that the value of charge-transfer resistance of the NiO-NFs modified carbon paste electrode (NiO-NFs/CPE) is much smaller than that CPE, indicating a faster electron-transfer process. The NiO-NFs are used as potential catalysts for electro-catalytic oxidation of ethylene glycol (EG) in 0.2 M NaOH solution. The results demonstrate that the NiO-NFs/CPE reveals good electro-catalytic activity towards EG oxidation, showing a suitable stability and robustness.     

Electrocatalytic oxidation of ethylene glycol and glycerol on nickel ion implanted-modified indium tin oxide electrode

The electrochemical behaviour of direct ethylene glycol and glycerol oxidation on a novel nickel ion implanted-modified indium tin oxide electrode (NiNPs/ITO) was investigated. The investigation is used to verify the feasibility of using the NiNPs/ITO electrode in the ethylene glycol and glycerol fuel cells. The size and morphology of nickel nanoparticles (NiNPs) on the substrate surface was determined by scanning electron microscopy (SEM). The cyclic voltammetry (CV) technique was utilized to characterize the typical electrochemical behaviours of the NiNPs/ITO electrode. In alkaline medium (0.2 M NaOH), a good redox behaviour of Ni(III)/Ni(II) coupled at the surface of modified electrodes can be observed. Electrochemical performances were measured by current–time curve technology. We find that the NiNPs/ITO electrode exhibits a satisfactory electrocatalytic activity toward ethylene glycol and glycerol with good stability, making it a prime candidate for use in ethylene glycol and glycerol fuel cells.     

Pd nanoparticles on self-doping-defects mesoporous carbon supports for highly active ethanol oxidation and ethylene glycol oxidation

The high activity electrocatalysts with low cost are crucial for large-scale direct alcohol fuel cells (DAFCs) applications. In this study, the “self-doping-defects” mesoporous carbon (SDMC) as support of uniformly-dispersed Pd nanoparticles (Pd/SDMC) was prepared for high active electrooxidation by a simple route without additional surfactant and acid treatment. According to the mutually corroborated experimental and theoretical calculation results, our route can significantly increase the carbon defect, which is conducive to the anchoring and uniform distribution of Pd nanoparticles. Meanwhile, the uniquely and hierarchically mesoporous nanostructure of SDMC provides abundant pathways for mass transport in the electrooxidation reaction. Benefitting from the above advantages, Pd/SDMC exhibits superior activity than commercial Pd/C and previously reported carbon-based electrocatalysts. The mass activities and specific activities of Pd/SDMC toward ethanol oxidation reaction (EOR) are 3404.3 mA mg⁻¹, 4.48 mA cm⁻², respectively. The mass activities and specific activities of Pd/SDMC for ethylene glycol oxidation reaction (EGOR) are 4002 mA mg⁻¹, 5.26 mA cm⁻², respectively. We believe that the facile strategy to synthesis mesoporous carbon with “self-doping” defects would promote large-scale DAFCs applications in the future.     

Nanostructured Pt and Pt-Sn catalysts supported on oxidized carbon nanotubes for ethanol and ethylene glycol electro-oxidation

Pt and Pt-Sn catalysts supported on oxidized carbon nanotubes were prepared by multiple potentiostatic pulses and tested for ethanol and ethylene glycol electro-oxidation in sulfuric acid. The composed nanostructured materials were characterized via SEM, TEM, EDX and XRD analysis. Small metal nanoparticles (4-6 nm) forming 3-D nanostructured agglomerates (25-100 nm) distributed over the carbon substrate were formed. XRD results showed that the bimetallic electrocatalysts consisted of a Pt single-phase material, suggesting the formation of solid solutions over the entire composition range. The tin content in the alloys was between 10 and 40 at. %.Cyclic voltammetry and chronoamperometry measurements at room temperature showed that at potentials below 0.5 V, the bimetallic catalyst with 40 at. % Sn exhibited the highest activity for ethanol and ethylene glycol oxidation, whereas at potentials above 0.5 V, the alloy with 25 at. % Sn displayed better performance. This behavior can be explained by the synergistic effect between the facilitation of alcohol oxidation via oxygen-containing species adsorbed on Sn atoms, the alteration of the electronic structure of Pt atoms that weakens CO and intermediates adsorption, and the adequate Pt ensembles size. Besides, the increment of the lattice parameter and the presence of grain boundaries can enhance the adsorption of the alcohols and favor the splitting of the C-C bond.     

Phase change characteristics of ethylene glycol solution‐based nanofluids for subzero thermal energy storage

Nanofluids, particularly water‐based nanofluids, have been extensively studied as liquid–solid phase change materials (PCMs) for thermal energy storage (TES). In this study, nanofluids with aqueous ethylene glycol (EG) solution as the base fluid are proposed as a novel PCM for cold thermal energy storage. Nanofluids were prepared by dispersing 0.1–0.4 wt% TiO₂ nanoparticles into 12, 22, and 34 vol.% EG solutions. The dispersion stability of the nanofluids was evaluated by Turbiscan Lab. The liquid–solid phase change characteristics of the nanofluids were also investigated. Phase change temperature (PCT), nucleation temperature, and half freezing time (HFT) were investigated in freezing experiments. Subcooling degree and HFT reduction were then calculated. Latent heat of solidification was measured using differential scanning calorimetry. Thermal conductivity was determined using the hot disk thermal constant analyzer. Experimental results show that the nanoparticles decreased the PCT of 34 vol.% EG solution but minimally influenced the PCT of 12 and 22 vol.% EG solutions. For all nanofluids, the nanoparticles decreased the subcooling degree, HFT, and latent heat but increased the thermal conductivity of the EG solutions. The mechanism of the improvement of the phase change characteristics and decrease in latent heat by the nanoparticles was discussed. The nanoparticles simultaneously served as nucleating agent that induced crystal nucleation and as impurities that disturbed the growth of water crystals in EG solution‐based nanofluids. Copyright © 2016 John Wiley & Sons, Ltd.     

Rapid room-temperature synthesis of Pd nanodendrites on reduced graphene oxide for catalytic oxidation of ethylene glycol and glycerol

In this paper, a simple, fast, and green method is developed for preparation of uniform Pd nanodendrites anchored on reduced graphene oxide (Pd/RGO) at room temperature, with the assistance of octylphenoxypolye thoxyethanol (NP-40) as a soft template, while no seed, organic solvent, or special apparatus involved. The as-prepared nanocomposites show the improved CO tolerance, enhanced catalytic activity, and better stability for ethylene glycol (EG) and glycerol (Gly) electrooxidation in alkaline media, compared with commercial Pd black and Pd/C catalysts. The synthetic strategy can be extended to fabricate other electrocatalysts in direct alcohol fuel cells.     

Real-time monitoring of hemicellulose liquefaction in ethylene glycol

Xylan was used as a model material to study the liquefaction of hemicellulose in the presence of ethylene glycol. The ReactIR^TM reaction analysis system was used to monitor the entire liquefaction process online. The results showed that xylan was decomposed and transferred to liquid phase. The gel permeation chromatography results of the liquid products showed that the weight average molecular of xylan decreased signi?cantly to around 1728 g/mol after liquefaction. Gas chromatography-mass spectrometry revealed that the ethylene glycol liquefaction products from xylan include ethylene glycol and its derivatives, alcohols, aldehydes, ketones, some acids and their esters.     

Ethylene glycol biodegradation in microbial fuel cell

Ethylene glycol is an environmental pollutant, which exists in airport runoff and industrial waste. In this article, biodegradation of ethylene glycol in a two-chamber, batch-mode microbial fuel cell was investigated. Glucose and ethylene glycol at different concentrations were used as carbon and energy sources. Chemical oxygen demand removal in the range of 92–98% indicated that microbial fuel cell can be used for biodegradation of ethylene glycol. Ethylene glycol also improved power generation and the maximum power density was 5.72 mW/m² (137.32 mW/m³), with respect to the same glucose and ethylene glycol concentrations (500 ppm).     

Comprehensive understanding of electro-oxidation of ethylene glycol

In the present article, a full investigation of the electrochemical characteristics of the electro-oxidation reaction of ethylene glycol on platinum (Pt) electrode in sulfuric acid has been performed to comprehensively understand and explore the details of the reaction mechanism. The dependence of the basic characteristics of the potentiostatic-mode electrochemical impedance spectroscopy (EIS) on the externally applied potentials has been studied in detail. The influence of the externally applied potentials and the ethylene glycol concentration on the galvanostatic potential's oscillation has been investigated in-depth. Finally, the origin of all oxidation/reduction peaks in the cyclic voltammetries (CV) has been discussed based on the CV and linear sweeping measurements and the reports by other groups.     

Hydrolysis characteristics of calcium hydride (CaH2) powder in the presence of ethylene glycol,methanol, and ethanol for controllable hydrogen production

Calcium hydride (CaH₂) reacts vigorously with water, liberating hydrogen gas. For the development of an effective hydrogen storage system, it is an absolute necessity to control the rate of hydrogen production. In the present study, the effects of different solvent, ethylene glycol, methanol, and ethanol, on the hydrolysis of CaH₂ for controllable hydrogen production were investigated. Reactions were performed at different temperatures (20, 40, and 60°C) in order to calculate the kinetic parameters. The Arrhenius equation was used to calculate the activation energies. The activation of energy of the hydrolysis reaction of CaH₂ in an ethanol solution (E_a = 20.03 kJ/mol) was found to be less than the other reactions.     

Hydrothermal synthesis of MoO3 nanobelts utilizing poly(ethylene glycol)

Metal oxide nanostructures hold enormous potential for electrochemical applications. While thin films of polymer-modified metal oxide electrodes have been widely investigated, there have been a few studies on polymer-modified nanopowders. We report the synthesis of pure molybdenum trioxide (MoO₃), pristine and aged nanobelts using hydrothermal method with poly(ethylene glycol) (PEG). Scanning electron microscope (SEM) images reveal the nanobelts to have dimensions of 1–5 μm in length and 100–600 nm in diameter. The electrochemical measurements show that PEG-used aged MoO₃ nanobelts have higher specific charge capacity than the PEG-free MoO₃ and PEG-used pristine MoO₃ nanobelts.     

In-situ synthesis of palladium-base binary metal oxide nanoparticles with enhanced electrocatalytic activity for ethylene glycol and glycerol oxidation

To achieve the better electrocatalytic activity and stability of Pd-base catalysts for ethylene glycol and glycerol oxidation reactions, a novel Pd-base binary PdCo oxides nanoparticles (PdPdO-CoO_x) was synthesized by in-situ oxidation of PdCo precursor. The strategy was simple, mild, green and efficient. The prepared nanoparticles exhibited a mutually connected, fused irregular nanoparticles in TEM. The as-synthesized PdPdO-CoO_x (1:4) nanoparticles displayed prominent catalytic activity (5.82 A $\mathrm{m}{\mathrm{g}}_{\mathrm{Pd}}^{\mathrm{?}1}$ for ethylene glycol and 5.16 A $\mathrm{m}{\mathrm{g}}_{\mathrm{Pd}}^{\mathrm{?}1}$ for glycerol) for ethylene glycol and glycerol oxidation reactions in alkaline solution compared to the commercial Pt/C (1.64 A $\mathrm{m}{\mathrm{g}}_{\mathrm{Pt}}^{\mathrm{?}1}$ for ethylene glycol and 1.48 A $\mathrm{m}{\mathrm{g}}_{\mathrm{Pt}}^{\mathrm{?}1}$ for glycerol) catalyst. The improved electrocatalytic activity of PdPdO-CoO_x catalyst mainly ascribes to the producing Strong Metal-Support Interactions (SMSI) between PdO-CoO_x and Pd nanoparticles, the synergistic effect between PdO and CoO_x and the presence of CoO_x promoved hydroxyl adsorption at lower potentials. Combined with the simple synthetic method, lower cost and good performance, PdPdO-CoO_x is a promising catalyst for direct fuel cells.     

A study of tri(ethylene glycol)-substituted trimethylsilane (1NM3)/LiBOB as lithium battery electrolyte

Silicon-based electrolyte has emerged as a primary candidate for the development of large lithium-ion batteries for electric vehicle (EV) and other systems in which safety is a primary consideration. Comparing to the electrolyte used in the conventional lithium-ion batteries, which are flammable, volatile, and highly reactive organic carbonate solvents, silicon-based electrolytes are thermally and chemically stable, less flammable and environmental benign. Tri(ethylene glycol)-substituted trimethylsilane (1NM3) was identified as a focus of investigation due to its high conductivity and low viscosity. We present the results of a systematic investigation of the 1NM3-based electrolytes with lithium bis(oxalate)borate (LiBOB) salt, including temperature dependent ionic conductivity and lithium cell performance. Lithium-ion cell with LiNi_1/3Co_1/3Mn_1/3O₂ as the positive electrode and MAG graphite as the negative electrode has shown excellent cyclability using 1NM3-LiBOB as electrolyte.