The purely aqueous system of phospholipase D (PLD)-mediated transphosphatidylation using pre-existing carriers for the adsorption of phosphatidylcholine (PC) to act as an "artificial interface" was introduced to replace the liquid-liquid system. Toxic organic solvents are avoided during the reaction, and the free enzyme can be simply reused by centrifugation. Special attention has been paid to the effect of the pore diameter and surface area of silica gel 60H covered with PC molecules on the yield of phosphatidylserine (PS). Results indicated that the highest PS yield of 99.5% was achieved. Moreover, 73.6% of the yield of PS was obtained after being used for six batches. This is the first description of the remarkably high reusability of free enzymes for enzymatic synthesis of PS as well. The excellent results make the aqueous-solid system more promising candidates for the industrial production of PS.
Abstract:In this paper, a catalyst of hollow PdCu alloy nanocubes supported on nitrogendoped graphene support (H-PdCu/ppy-NG) is successfully synthesized using a simple onepot template-free method. Two other catalyst materials such as solid PdCu alloy particles supported on this same nitrogen-doped graphene support (PdCu/ppy-NG) and hollow PdCu alloy nanocubes supported on the reduced graphene oxide support (H-PdCu/RGO) are also prepared using the similar synthesis conditions for comparison. It is found that, among these three catalyst materials, H-PdCu/ppy-NG gives the highest electrochemical active area and both the most uniformity and dispersibility of H-PdCu particles. Electrochemical tests show that the H-PdCu/ppy-NG catalyst can give the best electrocatalytic activity and stability towards the ethanol electrooxidation when compared to other two catalysts. Therefore, H-PdCu/ppy-NG should be a promising catalyst candidate for anodic ethanol oxidation in direct ethanol fuel cells.
OPEN ACCESSCatalysts 2015, 5 748
In this paper, a low palladium dosage hybrid catalyst (Pd/Fe 2 O 3 ) for ethanol electrooxidation promoted by Fe 2 O 3 has been fabricated by a facile solvothermal approach. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses reveal that the prepared face-centered cubic Pd nanoparticles with the average diameter of ca. 5 nm are well dispersed on the surface of the as-prepared dendritic Fe 2 O 3 . The resulting Pd/Fe 2 O 3 hybrid catalyst with a total loading of 8.4 wt% Pd shows higher mass activity (450.8 mA mg À1 Pd) than Pd/XC-72 catalyst (359.9 mA mg À1 Pd) and JM commercial 20% Pt/C catalyst (144.0 mA mg À1 Pt) towards ethanol electrooxidation, and better stability as well. Fe 2 O 3 has a promoting effect on oxidizing and removing the adsorbed CO-like intermediate species during electrooxidation of ethanol. These results indicate that due to the low cost and enhanced performance, the Pd/Fe 2 O 3 hybrid catalyst may be a superior candidate for direct ethanol fuel cells (DEFCs).
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