Abstract:The catalyst layers for polymer-electrolyte-membrane (PEM) fuel cells were fabricated by deposition of platinum directly onto the gas diffusion layer using pulsed laser deposition (PLD). This technique reduced the number of steps required to synthesize the catalyst layers and the amount of Pt loading required. PEM fuel cells with various Pt loadings for the cathode were investigated. With a cathode Pt loading of 100 µg·cm −2 , the current density of a single cell reached 1205 mA·cm −2 at 0.6 V, which was close to that of a single cell using an E-TEK (trademark) Pt/C electrode with a cathode Pt loading of 400 µg·cm −2 . Furthermore, for a PEM fuel cell with both electrodes prepared by PLD and a total anode and cathode Pt loading of 117 µg·cm −2 , the overall Pt mass-specific power density at 0.6 V reached 7.43 kW·g −1 , which was five times that of a fuel cell with E-TEK Pt/C electrodes. The high mass-specific power density was due to that a very thin nanoporous Pt layer was deposited directly onto the gas diffusion layer, which made good contact with the Nafion membrane and thus resulted in a low-resistance membrane electrode assembly.

A series of five-membered ring aluminum complexes bearing thiol-Schiff base ligands were synthesized, and their application in the ring-opening polymerization of ε-caprolactone (CL) was investigated.

Fatty liver diseases, common metabolic diseases in chickens, can lead to a decrease in egg production and sudden death of chickens. To solve problems caused by the diseases, reliable chicken models of fatty liver disease are required. To generate chicken models of fatty liver, 7-week-old ISA female chickens were fed with a control diet (17% protein, 5.3% fat, and 1,300 mg/kg choline), a low protein and high fat diet ( LPHF , 13% protein, 9.1% fat, and 1,300 mg/kg choline), a high cholesterol with low choline diet ( CLC , 17% protein, 7.6% fat with additional 2% cholesterol, and 800 mg/kg choline), a low protein, high fat, high cholesterol, and low choline diet ( LPHFCLC , 13% protein, 12.6% fat with additional 2% cholesterol, and 800 mg/kg choline) for 4 wk. Our data showed that the CLC and LPHFCLC diets induced hyperlipidemia. Histological examination and the content of hepatic lipids indicated that the CLC and LPHFCLC diets induced hepatic steatosis. Plasma dipeptidyl peptidase 4, a biomarker of fatty liver diseases in laying hens, increased in chickens fed with the CLC or LPHFCLC diets. Hepatic ballooning and immune infiltration were observed in these livers accompanied by elevated interleukin 1 beta and lipopolysaccharide induced tumor necrosis factor mRNAs suggesting that the CLC and LPHFCLC diets also caused steatohepatitis in these livers. These diets also induced hepatic steatosis in Plymouth Rock chickens. Thus, the CLC and LPHFCLC diets can be used to generate models for fatty liver diseases in different strains of chickens. In ISA chickens fed with the CLC diet, peroxisome proliferator-activated receptor γ, sterol regulatory element binding transcription factor 1, and fatty acid synthase mRNAs increased in the livers, suggesting that lipogenesis was enhanced by the CLC treatment. Our data show that treatment with CLC or LPHFCLC for 4 wk induces fatty liver disease in chickens. These diets can be utilized to rapidly generate chicken models for fatty liver research.

To improve the properties of mesoporous carbon (MC), used as a catalyst support within electrodes, MC fibers (MCFs) were successfully synthesized by combining organic–organic self-assembly and electrospinning deposition and optimizing heat treatment conditions. The pore structure was controlled by varying the experimental conditions. Among MCFs, MCF-A, which was made in the most acidic condition, resulted in the largest pore diameter (4–5 nm), and the porous structure and carbonization degree were further optimized by adjusting heat treatment conditions. Then, since the fiber structure is expected to have an advantage when MCFs are applied to devices, MCF-A layers were prepared by spray printing. For the resistance to compression, MCF-A layers showed higher resistance (5.5% change in thickness) than the bulk MC layer (12.8% change in thickness). The through-plane resistance was lower when the fiber structure remained more within the thin layer, for example, +8 mΩ for 450 rpm milled MCF-A and +12 mΩ for 800 rpm milled MCF-A against the gas diffusion layer (GDL) 25BC carbon paper without a carbon layer coating. The additional advantages of MCF-A compared with bulk MC demonstrate that MCF-A has the potential to be used as a catalyst support within electrodes in energy devices.

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Mesoporous carbon fiber (MCF) with the pore diameter of 5 nm and the BET surface area of 380 m2 g-1 has been analyzed as an electrocatalyst for PEFC after depositing Pt nanoparticles. Fundamental electrochemical characteristics of Pt deposited MCF has been compared with Pt deposited bulk mesoporous carbon and a commercial electrocatalyst, Pt deposited on Ketjen black. We have found that there is not much difference on fundamental oxygen reduction reaction activity among these three electrocatalysts. Therefore, fiber structure in MCF is expected for an advantage on constructing three dimensional cathode structure without changing fundamental electrochemical aspects.

Due to the low conductivity of sulfur and the dissolution of polysul des, the research and application of lithium-sulfur (Li-S) batteries have encountered certain resistance. Increasing conductivity and introducing polarity into the sulfur host can effectively overcome these long-standing problems. Herein, We rst prepared Co 3 W 3 C@ C@ CNTs / S material and used it in the cathode of lithium-sulfur batteries,The existence of carboxylated CNTs can form a conductive network, accelerate the transmission of electrons and improve the rate performance, and polar Co 3 W 3 C can form a strong interaction with polysul de intermediates, effectively inhibiting its shuttle effect, improving the utilization of sulfur cathode electrodes, and improving the capacity and cycle stability. The Co 3 W 3 C@C@CNTs / S electrode material has a capacity of 1,093 mA h g-1 at a 0.1 A g − 1 and 482 mA h g-1 at 5 A g − 1 . Even after 500 cycles of 2 A g − 1 , the capacity of each cycle is only reduced by 0.08%. The excellent stability of this material can provide a new idea for the future development of lithium-sulfur batteries.

A high-surface area (572 m2 g–1) dendritic mesoporous silica (KCC-1) was synthesized successfully and used as a support to confine Pt–Ni bimetallic nanoparticles (NPs). It is revealed that the Pt–Ni NPs are highly dispersed with an ultra-small size of 1.0 nm, and the large specific surface area as well as the abundant mesoporous structure of dendritic KCC-1 can effectively promote the dispersion and the thermal stability of Pt–Ni nanoparticles, thus significantly improving the CO oxidation activity. Compared with monometallic 1% Pt/KCC-1 and 1% Ni/KCC-1 catalysts, the combination of Pt and Ni together with a suitable ratio can further enhance the activity of the catalyst due to the synergetic effect between Pt and Ni. Over the 1% Pt7Ni3/KCC-1, the optimal catalyst in this study, 100% CO conversion was achieved at 100 °C. The incorporation of Ni into Pt leads to a reduction in the amount of noble metal required while simultaneously enhancing catalytic activity. This study offers a pathway for designing CO oxidation catalysts with low precious metal loading, yet exhibiting superior catalytic activity.