Self-Assembled Pt/MoCx/MWCNTs Nano Catalyst for Ethanol Electrooxidation of Fuel Cells.

Direct ethanol fuel cells (DEFCs) have attracted more and more attention because of their unique advantages such as low cost and low toxicity. However, sluggish C-C bond cleavage during the ethanol electrooxidation reaction (EOR) in acidic media results in a lower energy yield and gravely hinders the commercialization of DEFCs. Therefore, it is very necessary to develop an anode catalyst with high performance, high stability and low cost to solve this problem. In this paper, Pt/MoCx/MWCNTs nanocomposites with different mass ratios of PtMo were obtained through a molecular self-assembly technology. The structure and morphology of Pt/MoCx/MWCNTs nanocomposites were characterized by several techniques such as XRD, FESEM, XPS, etc. The electrochemical performance and stability of Pt/WCx/MWCNTs electrocatalysts toward EOR were investigated in acid electrolytes. The results show that PtMo exists in the form of alloy. The size of Pt/MoCx nanoparticles is very uniform with an average size of ∼24 nm. The Pt/MoC0.25/MWCNTs exhibits excellent electrocatalytic activities with an electrochemically active surface area of 37.1 m2 g-1, a peak current density of 610.4 mA mgPt -1 and a steady-state current density of 39.8 mA mgPt -1 after 7,200 s, suggesting that the Pt/MoC0.25/MWCNTs is a very promising candidate for application in EOR of DEFCs.

Selective Phosphoranation of Unactivated Alkynes with Phosphonium Cation To Achieve Isoquinoline Synthesis.

We herein develop a selective phosphoranation of alkynes with phosphonium cation, which directs a concise approach to isoquinolines from unactivated alkyne and nitrile feedstocks in a single step. Mechanistic studies suggest that the annulation reaction is initiated by the unprecedented phosphoranation of alkynes, thus representing a unique reaction pattern of phosphonium salts and distinguishing it from existing protocols that largely rely on the utilization of highly functionalized imines/oximes and/or highly polarized alkynes.

Core-Shell Structured PtxMoy@TiO2 Nanoparticles Synthesized by Reverse Microemulsion for Methanol Electrooxidation of Fuel Cells.

The high price of catalyst and poor durability still restrict the development of fuel cells. In this work, core-shell structured PtxMoy@TiO2 nanoparticles with low Pt content are prepared by a reverse microemulsion method. The morphologies, particle size, structure, and composition of PtxMoy@TiO2 nanoparticles are examined by several techniques such as X-ray Diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy, etc. The PtxMoy@TiO2 electrocatalysts show significantly higher catalytic activity and better durability for methanol oxidation than the commercial Pt/C (ETEK). Compared to Pt/C catalyst, the enhancement of the electrochemical performance of PtxMoy@TiO2 electrocatalysts can be attributed to the core-shell structure and the shift of the d-band center of Pt atoms, which can weaken the adsorption strength toward CO molecules, facilitate the removal of the CO groups and improve electrocatalytic activity. The development of PtxMoy@TiO2 electrocatalysts is promising to reduce the use of noble metal Pt and has a great potential for application in fuel cells.

Mesoporous Silica Nanospheres Impregnated with 12-Phosphotungstic Acid as Inorganic Filler of Nafion Membrane for Proton Exchange Membrane Fuel Cells.

In this work, a novel nanocomposite material, hollow mesoporous silica nanosphere impregnated with 12-phosphotungstic acid, briefed as HMSN-I, was synthesized by a vacuum-assisted impregnation method. The HMSN-I was used as an inorganic filler to synthesize Nafion-based composite membranes for the high temperature and low humidity operation of proton exchange membrane fuel cells (PEMFCs). The Nafion/HMSN-I composite membrane showed much higher conductivity than the pristine Nafion membrane under the identical conditions. The cell with the Nafion/HMSN-I composite membrane demonstrated significantly enhanced cell performance and stability in high temperature and low humidity environment. The mechanism can be ascribed to the enhanced proton conductivity and water retention ability of the composite membrane, which is very promising for the development of high temperature and low humidity PEMFCs.