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Nano sized copper oxide-zirconia particles were prepared by using a sol-gel technique. The phase change with the calcinations temperature was also investigated for the sample containing 30 wt% copper. It was found that the calcinations temperature strongly influenced the interaction between the active species and support and hence the structure and catalytic performance. Low calcinations temperature yielded poorly crystallized catalysts and favored the formation of a Cu(OH)₂ and Zr(OH)₄ like structure. The results show that cubic ZrO₂ and copper oxide were present below calcinations at 400°C, and cubic ZrO₂ with some amount of monoclinic ZrO₂ and tetragonal ZrO₂, as well as copper oxide, formed after calcinations at 500°C. However, below heating at 500°C, amorphous compounds were obtained; suggesting that 500°C could be a phase transition point. The incorporation of copper in the ZrO₂ lattice resulted in a loss of order in the ZrO₂ structure when calcined at 500°C, with a further increase in the calcinations temperature leading to the phase change. In this work, the latest results on nano crystalline CuO-ZrO₂ as the catalyst for hydrogen synthesis from methanol is reported. The effect of calcinations temperature on the nanoparticle structure of catalyst is focused.

Although biomass-derived metal-free electrocatalysts for oxygen reduction reaction (ORR) have garnered increasing attention, their ORR performance is lower than that of commercial 20% Pt/C. To improve their ORR performance, a series of porous carbons with high $N$ contents are prepared by pyrolyzing a mixture of spinach leaf powder and urea at different mass ratios (1:0, 1:5, 1:10, and 1:15) at a high temperature; the resultant materials are labeled as S-850, S-850-5, S-850-10, and S-850-15, respectively. The results indicate that the $N$ contents in the as-synthesized S-850, S-850-5, S-850-10, and S-850-15 products are 5.43, 5.74, 5.93, and 5.93 at%, respectively, which gradually increase with increasing urea contents, while the $P$ and $S$ contents (0.7 and 0.3 at%, respectively) show no change. Among all the as-synthesized products, the sample obtained by the addition of 10 wt.% urea (S-850-10) exhibits the best ORR catalytic performance in an O₂-saturated 0.1 M KOH solution with a half-potential of 0.748 V and a diffusion-limited current density of −4.76 mA cm${}^{-2}$ at 0.4 V. The half-potential and diffusion-limited current density of S-850-10 are improved by 0.53% and 8.61% compared to those of S-850 (0.744 V and −4.35 mA cm${}^{-2}$ at 0.4 V, respectively). These findings indicate that urea can be used as an $N$ resource to increase the $N$ content of biomass-derived metal-free porous carbon, enhancing its ORR performance.

In this paper, the design methodology of a parallel-resonant $LC$ converter for fuel cell applications in the electric vehicle is proposed in order to achieve high efficiency. Although the converter is unidirectional, it is interposed between the fuel cell and the DC link. Additionally, the converter is made up of two full bridges, an $LC$ resonant filter and a planar transformer. The use of a high-frequency transformer enables to minimize the converter size and the weight, to produce a higher voltage in the secondary side from an input voltage (fuel cell) and to isolate the full bridges. Furthermore, the rectifier diodes operate with a zero-current switching. Therefore, an experimental converter prototype has been designed, simulated, built and tested in the laboratory. Finally, a prototype having 30V as an input and 150V as an output with 500W is designed to demonstrate and analyze the proposed converter.

In this paper we report the electrochemical behavior of heat-treated carbon blacks and Pt/C catalysts. Cyclic voltammetry indicates that the heat-treated carbon black as catalyst support does not improve the Pt/C catalyst's activity for methanol oxidation. An XPS study of a Pt-loaded carbon black indicates that the amounts of oxidized platinum and oxygen-functional groups on catalysts are decreased when the platinum particles are deposited on the heat-treated carbon surface. These changes in the surface and crystalline structural properties of carbon materials lead to the catalytic activity change in methanol electro-oxidation.

The cuprous oxide nanoparticles were prepared with glucose as reducing agent by a wet-chemical method. The composition and structure of the catalysts were characterized with XRD and SEM analysis. The catalytic activity and stability of the catalyst for the H₂O₂ reduction were studied using the curves of cyclic voltammetry and chronoamperometry. The results showed that the crystal structure of the synthesized Cu₂O was the pure cubic phase and the crystallite size was about 19.5 nm. The Cu₂O powder was spherical and the average diameter of the spheres is about 1.0 μm. The Cu₂O nanoparticles were active for H₂O₂ electroreduction and the current density was about 30 mA cm^-2 at E = -0.4 V.

A variety of modification approaches such as cross-linking and nano blending have been explored to prepare efficient membranes based on Sulfonated polyether ether ketone (SPEEK). The addition filler is also one of the most widely used approaches to modify the SPEEK. The crosslinked membranes were utilized as proton exchange membranes (PEM) for fuel cell application. The performances of these composite membranes were comparative researched in terms of water uptake, ion exchange capacity, proton conductivity, and methanol permeability.While the nanohybrid membranes display remarkably enhanced proton conduction property due to the incorporation of additional sites for proton transport and the formation of well-connected channels by bridging the hydrophilic domains in SPEEK matrix. The as-prepared nanohybrid membranes also show elevated thermal and mechanical stabilities as well as decreased methanol permeability.

The work presents the synthesis and characterization of amidated pectin (AP) based polymer electrolyte membranes (PEM) crosslinked with glutaraldehyde (GA). The prepared membranes are characterized by Fourier transform infrared spectroscopy (FTIR), organic elemental analysis, X-ray diffraction studies (XRD), thermogravimetric analysis (TGA) and impedance spectroscopy. Mechanical properties of the membranes are evaluated by tensile tests. The degree of amidation (DA), molar and mass reaction yields (Y_M and Y_N) are calculated based on the results of organic elemental analysis. FTIR spectroscopy indicated the presence of primary and secondary amide absorption bands. XRD pattern of membranes clearly indicates that there is a considerable increase in crystallinity as compared to parent pectin. TGA studies indicate that AP is less thermally stable than reference pectin. A maximum room temperature conductivity of 1.098 × 10^-3Scm^-1 is obtained in the membrane, which is designated as AP-3. These properties make them good candidates for low cost biopolymer electrolyte membranes for fuel cell applications.

Sunken hollow carbon spheres (SHCs) are prepared by using glucose as carbon source and polystyrene spheres (PSs) as templates. Pt particles are then loaded on the SHCs as electrocatalyst and used for catalyzing both methanol oxidation and oxygen reduction reaction (ORR) in acidic media. Physical measurements show that the SHCs are formed due to sinking of hollow carbon spheres. It can be imagined that the SHCs have the similar specific surface area as hollow carbon spheres with reduced volume. Moreover, the SHCs have high surface area (786.3 m² ⋅ g^-1) with hollow and sunken structure are beneficial for the uniform dispersion of the noble metal particles and efficiently improve the mass transfer in catalytic reactions. The cyclic voltammogram measurements show that the current densities on Pt/SHC electrocatalyst are 2.1 times ) that on commercial Pt/C for methanol oxidation and 1.5 times () that on Pt/C for ORR at the same Pt loadings, being promising candidate for fuel cell electrocatalyst.

Enhancing oxygen reduction reaction (ORR) activity and simultaneously reducing usage of noble metal catalysts are significantly important both in fundamental and applied science communities for polymer electrolyte fuel cells (PEFCs). In this work, we confirm the proton conductor (perfluorosulfonic acid, containing $-$SO₃H) can promote the specific activity $(I_{\text{s}})$ of metal catalysts toward ORR. Herein, Pt nanoparticles (NPs) with a small and narrow size distribution are encapsulated with perfluorosulfonic acid through a simple colloidal route. The resulting catalyst obtains about two times $(I_{\text{s}})$ towards ORR than that of the pristine Pt/C. Significantly, the amount of $-$SO₃H groups is controlled by a heat-treatment method to investigate the influence of $-$SO₃H groups on $(I_{\text{s}})$. The results evidence the contribution of $-$SO₃H groups to elevating the ORR specific activity. The mechanism can be ascribed to the $-$SO₃H groups which effectively promote the transfer process of reaction species (e.g., H${}^{+}$, H₂O), improving the triple-phase boundary (TPB).

In this study, we report the findings that the C–N composites containing Ni and Co (Ni₁Co₁/C–N, Ni₃Co₁/C–N, Ni₆Co₁/C–N, Ni₉Co₁/C–N, Ni${}_{10}$Co₀/C–N and Ni₀Co${}_{10}$/C–N) can be produced by direct pyrolysis of the NiCo-doped polyaniline (PANI) precursors in N₂ atmosphere at 800${}^{\circ }$C and show efficient electroactivity for oxygen reduction reaction (ORR) in alkaline media. Distribution and compositions of the catalysts were characterized by SEM, TEM, EDS and XRD techniques. The catalysts were loaded on carbon paper to prepare gas diffusion electrodes, in which electrocatalytic activity for ORR in alkaline media was investigated by voltammetric techniques. The ORR current density on these carbon paper-supported NiCo/C–N catalysts exhibits a linear increase with the negative shift of ORR potential. The ORR onset potential is around $-$0.2V (versus Ag/AgCl) in alkaline media. Among the prepared catalysts, the catalyst Ni₆Co₁/C–N presents the largest ORR current density, which is 68.5mAcm${}^{-2}$@$-$0.8V (versus Ag/AgCl) in alkaline media. Moreover, Ni₆Co₁/C–N catalyst also presents good electrocatalytic activity stability for ORR.

Cobalt phosphide (CoP) has aroused extensive research interest in a field of electrochemical application due to its excellent catalytic activities. CoP and its compounds have been widely reported using in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, few reports about CoP as electrocatalysts for oxygen reduction reaction (ORR) were presented. In this work, we prepare reduced graphene-oxide(rGO)-loaded CoP (rGO@CoP) as an electrocatalyst for ORR through in situ hydrothermal treatment. The rGO@CoP as ORR catalyst exhibits excellent activities where its onset potential has a positive increase of 129mV, and the ORR potential achieves an increase of 330mV at a current density of 1.0mAcm${}^{-2}$ compared with that of pure CoP. The current density is also significantly improved with an increase of 0.51mAcm${}^{-2}$ at $-$350mV, and the Tafel slope has a decrease of 19mV dec${}^{-1}$. Further tests show that the electron transfer number of rGO@CoP is 3.66, which is larger than 2.19 of pure CoP, indicating that it is dominated by a four-electron transfer pathway. Moreover, its stability (remained 98.6% current after working 6000s) and methanol tolerance are outstanding. These results show that rGO@CoP may be considered to replace traditional Pt-based ORR catalysts for fuel cells, and rGO loading has been proven to be an effective strategy to enhance the ORR performance of CoP, which may provide a new idea to synthesize transition metal phosphides as ORR catalysts.

Improving the efficiency of glucose oxidation reaction (GOR) is extremely important to build high performance nonenzymatic glucose sensors and fuel cells. In this work, we designed a novel binary ($\alpha$–$\beta )$ NiS/PANI nanorods electrocatalyst with polyaniline (PANI) as the substrates and binary ($\alpha$–$\beta )$ NiS nanoparticles dispersing on the PANI nanorods. The as-prepared NiS/PANI nanorods were characterized by XRD, XPS and SEM. The electrochemical performance of NiS/PANI nanorods was evaluated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy, which showed highly improved catalytic efficiency for GOR. When used as anodic catalysts in nonenzymatic glucose fuel cells, NiS/PANI nanorods displayed much higher power density of 1343.39 $\mu \mathrm{\text{W}}\cdot {\mathrm{\text{cm}}}^{-2}$ with an open circuit voltage of 0.84 V. NiS/PANI/NiS nanorods also presented excellent nonenzymatic sensing performance for glucose detection including a wide sensitivity of 682.21 $\mu \mathrm{\text{A}}\cdot {\mathrm{\text{mM}}}^{-1}\cdot {\mathrm{\text{cm}}}^{-2}$ (10–9000 $\mu$M) and the low detection limit of 3.33 $\mu$M ($\mathrm{\text{S/N}}=3$). The obviously improved electrochemical properties of NiS/PANI/NiS nanorods for GOR may be due to the synergistic effect of binary ($\alpha$–$\beta )$ NiS and PANI nanorods.

A hierarchical carbon material containing nanopores (micropores and mesopores) and micrometric sized capillaries (macropores) is produced using a combination of hard and soft templates. The hard template is a polypropylene (PP) cloth which decomposes during pyrolysis leaving a macroporous structure. The soft template is a cationic polyelectrolyte which stabilizes the resorcinol/formaldehyde (RF) resin porous structure during drying to give a nanoporous RF resin. The method produces a nanocomposite of the porous RF resin with an imbibed PP cloth. The composite is then pyrolyzed in a inert gas atmosphere to render a carbon material having macropores as well as micro/mesopores. The material exhibits both a large surface area (S_BET = 742 ± 2 m²/g) due to nanopores and goof fluid permeability due to micrometric sized pores. The macropores can be oriented during fabrication. The nanoporous surface can be used to support metal nanoparticles for fuel cell while the macropores allow easy flux of gas and liquids through the monolithic material.

In this work, slurry spraying is evaluated as a deposition method of thin electrolytes for solid oxide fuel cells. This method is cost effective, uncomplicated and have several advantages in respect to widely used screen printing method. Influence of deposition parameters: slurry concentration, spraying pressure are discussed. Anode supported cells are produced with three different electrolyte thicknesses: 5, 10 and 20 μm showing flexibility of the developed method. Prepared fuel cells achieve satisfactory power densities of almost 1 W cm^-2 at 800°C. As evidenced by impedance spectroscopy, performance of cells is determined by the polarization resistance. Cross sections of cells show that all electrolyte layers are of high quality. Slurry spraying is a feasible method for fabrication of functional cells and can be easily scaled for large quantity production.

Catalysts are a key component of polymer electrolyte membrane fuel cells (PEMFCs). In this work, nitrogen-doped three-dimensional graphene-supported platinum (Pt-3DNG) catalysts are successfully prepared and characterized. SEM and TEM images show the Pt nanoparticles are uniformly dispersed in the sheets of nitrogen-doped 3DNG. Compared with that of the commercial Pt/C catalysts, Pt-3DNG show much better oxygen reduction reaction (ORR) activity and cycling stability, and the reduction in limit current density after 1000 cycles is only about 1.6% for the Pt-3DNG catalysts, whereas 7.2% for the commercial Pt/C catalysts. The single cell using Pt-3DNG catalysts in both the anode and the cathode show a higher peak power density (21.47mW cm${}^{-2})$ than that using commercial Pt/C catalysts (20.17mW cm${}^{-2})$ under the same conditions. These properties make this type of catalyst suitable for the application in PEMFCs.

In order to develop non-noble metal-based electrocatalysts for glucose oxidation, the Ni-doped, urchin-like Bi₂S₃ particles were prepared by a solvothermal method using the solvent of ethylene glycol/H₂O. The obtained products were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The background signal from capacitance current is relatively low and the electrocatalytic oxidation current of glucose relatively high due to the urchin-like nanostructure of Bi₂S₃ particles and high surface area where the presence of Bi also improves the electrocatalytic performance of Ni${}^{II}$/Ni${}^{III}$ shift.

This paper studies an absorption machine driven by the heat recovered from a Solid Oxide Fuel Cell (SOFC). The absorption unit was first evaluated by a cycle analysis determining the sensitivity to the main boundary conditions and to the internal parameters. Then a specific simulation code of all the different devices of the absorption machine was developed to evaluate the performance and size of the unit together with its operating condition limits.

In the present paper, the effect of desorption temperature on the performance of adsorption cooling systems driven by waste heat from fuel cells was analyzed. The studied adsorption cooling systems employ activated carbon fiber (ACF) of type A-20–ethanol and RD type silica gel–water as adsorbent–refrigerant pairs. Two different temperature levels of waste heat from polymer electrolyte fuel cell (PEFC) and solid oxide fuel cell (SOFC) are used as the heat source of the adsorption cooling systems. The adsorption cycles consist of one pair of adsorption–desorption heat exchanger, a condenser and an evaporator. System performance in terms of specific cooling capacity (SCC) and coefficient of performance (COP) are determined and compared between the studied two systems. Results show that silica gel–water based adsorption cooling system is preferable for effective utilization of relatively lower temperature heat source. At relatively high temperature heat source, COP of ACF–ethanol based adsorption system shows better performance than that of silica gel–water based adsorption system.

Direct oxidation of tryptophan on multi-wall carbon nanotubes modified glassy carbon electrode was examined. Surface poisoning, which was suppression of oxidative current caused from adsorption of oxidized compounds of amino acids through multiple redox scan, was observed on carbon material electrodes (multi-wall carbon nano tube(CNT), carbon powder(CP), Ketjen Black (KB) and glassy carbon(GC). It was found that CNT showed a highly inhibitory effect on the surface poisoning and high current value in the direct oxidation of tryptophan because of a π-π interaction between CNT and indole ring of tryptophan results from orbital mixing. This CNT modified GC electrode was applied to an anode in a fuel cell used with amino acids as fuel. As a result, the maximum of the power density showed 0.36 mW cm^-2 at 2.5 mA cm^-2 of the current density and 140 mV of the cell voltage.

Flight endurance is still a bottleneck for many types of unmanned air vehicle (UAV) applications. While battery technology improves over the years, for flights that last an entire day, batteries are still insufficient. Hydrogen-powered fuel cells offer an interesting alternative but pose stringent requirements on the platform. The required cruise power must be sufficiently low and flying with a pressurized tank poses new safety and shape constraints. This paper proposes a hybrid transitioning UAV that is optimized towards carrying a hydrogen tank and fuel cell. Hover is achieved using 12 redundant propellers connected to a dual Controller Area Network (CAN) bus and dual power supply. Forward flight is achieved using a tandem wing configuration. The tandem wing not only minimizes the required wingspan to minimize perturbations from gusts during hover, but it also handles the very large pitch inertia of the inline pressure tank and fuel cell very well. During forward flight, 8 of the 12 propellers are folded while the tip propellers counteract the tip vortexes. The propulsion is tested on a force balance and the selected fuel cell is tested in the lab. Finally, a prototype is built and tested in-flight using battery power. Stable hover, good transitioning properties, and stable forward flight are demonstrated.