An efficient and robust bifunctional electrocatalyst for both ORR and OER is highly desired for the applications in renewable energy technologies. Here, we prepare the carbonaceous microspheres (CMSs) by a facile hydrothermal treatment of glucose precursor and then dope the CMSs with La 2 O 3 , resulting in a high performance bifunctional electrocatalyst of La 2 O 3 @ CMSs. In alkaline solution, the La 2 O 3 @CMSs catalyzes oxygen reduction reactions (ORR) with an onset potential of 0.80 V versus RHE and an overpotential only of 600 mV to achieve a current density of 1.3 mA cm −2 . Meanwhile, oxygen evolution reaction (OER) at La 2 O 3 @CMSs electrode occurs at an onset potential of 1.60 V versus RHE and the overpotential is only 370 mV. Also, the as-prepared La 2 O 3 @CMSs exhibits high Faraday efficiency and long-term stability toward ORR and OER. Significantly, we demonstrate that La 2 O 3 @CMSs possesses surprisingly high mass activity, which is calculated to be 78.4 A g −1 for ORR and 831.5 A g −1 for OER, respectively. A potential window for ORR and OER at the modified electrode is estimated to be 0.80 V, implying a promising bifunctional electrocatalytical performance of La 2 O 3 @CMSs. The improvement of the bifunctional electrocatalytical activity may be due to the generation of active component of La−O and C−O at the surface and its synergistic interact with the La 2 O 3 @CMSs. This work not only provides a facile strategy for preparing highly efficient bifunctional electrocatalyst, but also offers an insight into the design of metal-oxides doped carbon materials for energy storage and conversion applications.
Bis(α-diimine) single nickel(ii) catalyst with strong electron-withdrawing group was applied to catalyze polymerization and copolymerization of norbornene and butyl methacrylate.
Crosslinked hydroxyl-conductive copolymer/silica composite membranes based on addition-type polynorbornene, poly(dodoxymethylene norbornene-co-norbornene-3-(trimethylpropyl ammonium)-functionalized silica (QP(DNB/ NB-SiO 2 ), were prepared by a sol-gel method. Copolymer composite membranes with different degree of quaternary ammonium functional silica, designated as QP(DNB/NBSiO 2 -X) (X 5 5, 10, 15 and 25 wt%, respectively), displayed good dimensional stabilities with low in-plane swelling rate of 1.32-3.7%, good mechanical properties with high elastic modulus of 605.4-756.8 MPa and high tensile strength of 13.2-20 Mpa. The achieved copolymer composite membranes could self-assemble into a microphase-separated morphology with randomly oriented long-range aliphatic chain/cylinder ionic channels that were imbedded in the hydrophobic PNB matrix. Among these membranes, the QP(DNB/NB-SiO 2 -25) showed the parameter with ionic conductivity of 9.33 3 10 23 S cm 21 , methanol permeability of 2.89 3 10 27 cm 2 s 21 , and ion-exchange capacity(IEC) of 1.19 3 10 23 mol g 21 . A current density of 82.3mA cm 22 , the open circuit voltage of 0.65 V and a peek power density of 32 mW cm 22 were obtained. POLYM. ENG. SCI., 58:13-21, 2018.
Enhancing the cathode capacity of lithium ion batteries (LIBs) has been one strategy to improve the energy density of batteries for electric vehicle applications, because of the limitation of inorganic cathode capacity.
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