Energy Focus
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ACS Nano DOI: 10.1021/nn1024434
Energy & Environmental Science DOI: 10.1039/C0EE00570C
A new method of forming porous titanium dioxide electrodes for use in solid-state dye-sensitized solar cells for faster electron transport, as an alternative to nanoparticle-based electrodes, has been developed. The new process uses titanium dioxide nanorods, which self assemble and join together to form a 3D network of fused single-crystalline nanowires very quickly from aqueous solution. The main aim is to speed up electron transport through the electrode structure and avoid recombination with ©2010, American Chemical Society/ACS Nano. holes. The new structure showed several orders of magnitude faster electron transport compared to conventional electrodes, and yielded a conversion efficiency of 4.9%.
Nano Letters DOI: 10.1021/nl102981d
A new nanomaterial for use in Li-ion battery anodes has been developed. The shape of the nanomaterial resembles a cone with a scoop of ice cream on top, hence the moniker “nanoscoop” by the researchers. The structure incorporates a carbon (C) nanorod base topped with a thin layer of nanoscale aluminum (Al) and a “scoop” of nanoscale silicon (Si). An anode made of arrays of this material was shown to withstand extremely high rates of charge and discharge that would cause conventional electrodes used in current Li-ion batteries to rapidly deteriorate and fail. The electrode was dem©2010, American Chemical Society/Nano Letters onstrated to charge/discharge at a rate 40 to 60 times faster than conventional battery anodes while maintaining a comparable energy density for more than 100 continuous charge/discharge cycles. The segmented structure of the nanoscoop allows strain, during the charging and discharging of Li ions, to be gradually transferred from the C base to the Al layer and finally to the Si scoop, thereby minimizing mismatch at the interfaces between the differentially strained materials. MRS BULLETIN
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VOLUME 36 • MARCH 2011
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www.mrs.org/bulletin • Energy Quarterly
Hematite (α-Fe2O3) is a very promising photoanode material for hydrogen production using solar radiation by photoelectrochemically splitting water, due to its unique combination of properties. With an energy bandgap of 2.1 eV, hematite photoanodes can reach solar-to-hydrogen conversion efficiencies as high as 15.5%. However, in practice, only a quarter of this theoretical limit has been achieved thus far, attributed to surface and bulk recombination losses connected with a low rate of water oxidation and short diffusion lengths 100 100 of the photogenerat80 80 ed minority carriers 60 60 (holes). The question of 40 40 the rate-limiting step in 20 20 hematite photoanodes and whether carrier re0 0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 combination occurs at VRME (Volt) the bulk or the surface has been under inves©2011, Royal Society of Chemistry/Energy & Environmental Science tigation. A report now presents a new approach to answering this fundamental question, using hydrogen peroxide as a hole scavenger that readily accepts holes
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