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Core-shell structured catalysts, made by placing either a monolayer or a thin layer of a noble metal on relatively cheap core-metal nanoparticles, are fascinating and promising fuel cell catalysts due to their high utilization of noble metals. Here, we report our development of a core-shell structured catalyst, Ru@Pt/C, generated by a novel and facile pulse electrochemical deposition (PED) approach. We demonstrate that compared with a commercial Pt/C catalyst, this novel catalyst achieves over four times higher mass activity towards the anodic oxidation of methanol, and 3.6 times higher mass activity towards the cathodic reduction of oxygen. Importantly, we find that the intrinsic activity of Pt in this Ru@Pt/C catalyst is doubled due to the formation of the core-shell structure. The catalyst also shows superior stability: even after 2000 scans, it still retains up to 90% of the peak current. Our findings demonstrate that this novel PED approach is a promising method for preparing high-performance core-shell catalysts for fuel cell applications. [ABSTRACT FROM AUTHOR]

We designed a novel aqueous rechargeable lithium battery with LiFePO 4 /C (LFP) and LiMn 2 O 4 /C (LMO) as the anode and cathode, respectively; then investigated the battery in Li 2 SO 4 aqueous electrolyte. We also studied the electrochemical behavior of LFP in aqueous electrolyte using cyclic voltammetry (CV). The material exhibited excellent electrochemical performance in the aqueous electrolyte, including good oxidation/reduction reversibility and cycling stability; almost no decays were observable after 200CV cycles. The diffusion coefficients of Li ions through the interface between the liquid electrolyte and the solid LiFePO 4 in terms of intercalation and deintercalation were 1.22 × 10 −14 and 9.97 × 10 −15 cm 2 /s, respectively. The material could be completely intercalated/deintercalated with Li ions in the aqueous electrolyte, indicating the excellent performance of LFP in an aqueous solution. Further, an aqueous rechargeable lithium battery (ARLB), which we fabricated using LFP as the anode and LMO as the cathode, also exhibited quite good performance in aqueous Li 2 SO 4 solution: after 1,000 charge–discharge cycles at 2 C, the capacity loss was less than 30%, indicating that this type of ARLB has excellent cycling stability and may be promising for future research and application. [ABSTRACT FROM AUTHOR]

A novel lithium-oxygen (Li-O 2 ) battery with a polymer gel electrolyte (PGE) membrane is successfully prepared. The membrane is a blend of cellulose acetate (CA) and poly(vinylidene fluoride- co -hexafluoropropylene) (P(VDF-HFP)) and is fabricated using a solution casting technique followed by impregnation with lithium bis(trifluoromethane sulfonimide) (LiTFSI) solution. We demonstrate that the PGE membrane has good electrolyte uptake and shows high ionic conductivity as well as excellent thermal and electrochemical stability. A Li-O 2 battery containing our PGE as the electrolyte and separator exhibits good rate capability and enhanced cycling capacity retention compared to a battery using commercial liquid electrolyte and a polyethylene (PE) separator under the same conditions. We attribute this enhanced performance to the PGE, which maybe restrain the diffusion of oxygen from the air cathode to the Li metal anode. This study may prove valuable for resolving the problem of poor cycling stability in Li-O 2 batteries caused by oxygen diffusion from cathode to anode. [ABSTRACT FROM AUTHOR]

Pd@Pt nanoparticles with a three-dimensional (3D) nanospherical shape have been prepared using a two-step approach in which the Pd nanospheres are synthesized controllably by a solvothermal method, and then a Pt monolayer is deposited on the Pd nanospheres using an underpotential deposition process. We systematically investigate (i) the influences of temperature and additive on the morphology of the Pd nanoparticles and (ii) the electrochemical activity of Pd@Pt for the oxygen reduction reaction (ORR). The Pd@Pt nanoparticles exhibit enhanced activity towards the ORR. The mass activity of Pt in the Pd@Pt nanospheres (1.03 A mgPt −1 ) is 3.3 times higher than that of commercial Pt/C (0.24 A mgPt −1 ). The catalyst enhanced activity may result from the 3D structure of the Pd nanospheres and the monolayer dispersion of Pt on the surface of the nanoparticles. [ABSTRACT FROM AUTHOR]