Tunable carots: Construction of the stable carotenoid wires with a specific conductance value is possible by the attachment of phenyl groups to the polyene chain to overcome the in vitro instability of natural carotenoids, the perfect molecular wires utilized in various biological processes. Diverse electronic natures of the substituents on the phenyl groups provide the carotenoids with tunable conductance (see figure).

Our lycopene synthesis highlights the expeditious assembly of the carbon skeleton by the use of a readily available ten-carbon unit, geraniol, rather than the original natural five-carbon building block, isopentenyl pyrophosphate. Furthermore, four oxidation steps by the enzyme desaturases to produce the conjugated carbon-carbon double bonds of lycopene are merged into one-pot double elimination reactions in our synthesis. These accomplished the highly efficient synthesis of all-(E)-lycopene from geraniol through a seven-step sequence in 51% overall yield.

A convergent synthetic method for new types of carotenoid compounds containing phenyl substituents at C(13) and C(13') has been developed by the coupling of allylic sulfone and 2,7-diphenyloct-4-enedials, followed by the double elimination strategy. These carotenoid compounds are fairly stable and legitimate candidates for nanosized molecular wires, which show diverse conductance values according to the electronic nature of the substituent group in the phenyl ring.

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membrane fuel cells (PEMFCs) use the chemical energy of both hydrogen and oxygen to generate electricity with high efficiency, zero pollution, and rapid start-up/shut-down at relatively low temperatures (<100 °C). [1,2] Because of these attractive characteristics, PEMFCs have considerable potential as power sources for diverse applications, particularly in automobiles; With the motivation, many manufacturers have successfully commercialized these applications. However, some critical issues, such as high cost, insufficient durability, and water management difficulty, still limit further commercialization of PEMFCs in the market. Therefore, to address these issues, novel technological breakthroughs are necessary. Accordingly, the United States (US) Department of Energy (DOE) has set 2025 technical targets for membrane electrode assembly (MEA) in fuel cells. The targets require almost two times prolonged fuel cell durability to 8000 h and reduced MEA cost by 15% compared to those of the current commercial achievement of 4100 h and $11.8 kW −1 . [3] MEA, which is the essential part of PEMFCs, where electrochemical reactions occur, comprises two catalyst layers (anode and cathode) and a proton exchange membrane (PEM).Generally, MEA is manufactured by two representative techniques, [4] i.e., decal transfer and direct coating methods. For the decal transfer process, catalyst ink or slurry is first coated onto the release films. Next, at high pressure and temperature above the glass transition temperature of the PEM, the coated films are transferred to the PEM which is prepared by casting the electrolyte ionomer to the backer film. For the direct coating process, catalyst inks are directly coated onto the PEM by spray coating or ink-jet printing. For these processes, membrane manufacturing and electrode-coating should be separately conducted, and different type of equipment is required for each process. To simplify manufacturing, direct membrane deposition (DMD) method has been extensively studied. [5][6][7][8][9][10] For the DMD process, without the free-standing membrane, PEM is directly coated onto the anode and cathode in which the catalyst layer is coated on a gas diffusion layer (GDL) via a single coating system (e.g., spray or ink-jet), and then layers are assembled after aligning membrane-coated For achieving economically viable polymer electrolyte membrane fuel cells (PEMFCs) in the commercial market, simplifying the fabrication process and manufacturing of robust membrane electrode assembly (MEA) are important. Herein, a single spray-coating method for developing a robust and freestanding reinforced Nafion composite membrane and electrodes is reported. By comparing the fabricated membrane's morphology under diverse process conditions including the nozzle-to-substrate distance and solution-loading rates, the optimized spray-coating for uniformly deposited spray-based membrane without any defects has been determined. To explain this optimized condition, a simple theoretical model based on the concept of the surfa...