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Nathan S. Lewis

Bio: Nathan S. Lewis is an academic researcher from California Institute of Technology. The author has contributed to research in topics: Semiconductor & Silicon. The author has an hindex of 112, co-authored 720 publications receiving 64808 citations. Previous affiliations of Nathan S. Lewis include Lawrence Berkeley National Laboratory & Massachusetts Institute of Technology.


Papers
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TL;DR: In this paper, the response of the open-circuit photovoltage, V/sub oc/, has been investigated with regard to changes in the minority carrier diffusion length, majority carrier density, shortcircuit photocurrent density, and cell temperature of n-Si/CH/sub 3/OH junctions.
Abstract: The response of the open-circuit photovoltage, V/sub oc/, has been investigated with regard to changes in the minority carrier diffusion length, majority carrier density, short-circuit photocurrent density, and cell temperature of n-Si/CH/sub 3/OH junctions. The reaction kinetics are observed to be first order in dopant density, minority carrier diffusion length, and photocurrent density. The activation barrier for carrier recombination, obtained from plots of V/sub oc/ vs. temperature, is 1.15 +/- 0.05 eV. An optimum dopant density for maximum V/sub oc/ is observed, and this is consistent with bulk lifetime measurements on similarly doped Si samples. The reaction kinetics are not sensitive to the concentration of redox species (at constant electrochemical potential), indicating minimal recombination losses due to poor interfacial charge transport rates. V/sub oc/ values for optimally doped systems (V/sub oc/ = 670 mV for 0.015 omega-cm n-Si samples at 20 mA/cm/sup 2/ photocurrent densities) represent the highest photovoltages obtained to date for any n-Si-based surface barrier device. Surface recombination velocity measurements at the n-Si/CH/sub 3/OH interface have been performed, and correlations between the surface recombination rate and the improvement in current-voltage properties have been investigated.

87 citations

Journal ArticleDOI
TL;DR: In this article, the stabilization of various semiconductor photoanodes is reviewed in the context of the electronic characteristics and a mechanistic analysis of the TiO_2 films, along with a discussion of the optical, catalytic, and electronic nature of NiO_x films for stabilization of semiconductor photos for water oxidation.

87 citations

Journal ArticleDOI
TL;DR: In this paper, cuprous oxide (Cu2O) photoelectrodes prepared by the thermal oxidation of Cu foils exhibited open-circuit voltages in excess of 800 mV in nonaqueous regenerative photo-electrochemical cells.
Abstract: P-Type cuprous oxide (Cu2O) photoelectrodes prepared by the thermal oxidation of Cu foils exhibited open-circuit voltages in excess of 800 mV in nonaqueous regenerative photoelectrochemical cells. In contact with the decamethylcobaltocene+/0 (Me10CoCp2+/0) redox couple, cuprous oxide yielded open-circuit voltage, Voc, values of 820 mV and short-circuit current density, Jsc, values of 3.1 mA cm−2 under simulated air mass 1.5 illumination. The energy-conversion efficiency of 1.5% was limited by solution absorption and optical reflection losses that reduced the short-circuit photocurrent density. Spectral response measurements demonstrated that the internal quantum yield approached unity in the 400–500 nm spectral range, but poor red response, attributable to bulk recombination, lowered the overall efficiency of the cell. X-Ray photoelectron spectroscopy and Auger electron spectroscopy indicated that the photoelectrodes had a high-quality cuprous oxide surface, and revealed no observable photocorrosion during operation in the nonaqueous electrolyte. The semiconductor/liquid junctions thus provide a noninvasive method to investigate the energy-conversion properties of cuprous oxide without the confounding factors of deleterious surface reactions.

86 citations

Journal ArticleDOI
TL;DR: In this article, ordered bilayers of close-packed polystyrene spheres were deposited onto (100)-oriented n-type single crystal Si surfaces, forming a physical mask through which Ni was evaporated to produce regularly spaced and regularly sized Si/Ni contacts.
Abstract: Nanosphere lithography has been used to prepare a series of ordered, periodic arrays of low barrier height nanometer-scale n-Si/Ni contacts interspersed among high barrier height n-Si/liquid contacts To form the arrays, ordered bilayers of close-packed polystyrene spheres were deposited onto (100)-oriented n-type single crystal Si surfaces The spheres formed a physical mask through which Ni was evaporated to produce regularly spaced and regularly sized Si/Ni contacts By varying the diameter of the latex spheres from 174 to 1530 nm, geometrically self-similar Si/Ni structures were produced having triangular Si/Ni regions with edge dimensions of 100−800 nm The resulting Si surfaces were used as electrodes in contact with a methanolic solution of LiClO_4 and 1,1‘-dimethylferrocene^(+/0) The current−voltage and photoresponse properties of these mixed barrier height contacts were strongly dependent on the size of the Ni regions, even though the fraction of the Si surface covered by Ni remained constant Electrodes formed from large-dimension Si/Ni and Si/electrolyte contacts behaved as expected for two area-weighted Schottky diodes operating independently and in parallel, whereas electrodes having nanoscale Si/Ni regions surrounded by Si/liquid contacts behaved in accord with effective barrier height theories that predict a “pinch-off” effect for mixed barrier height systems of sufficiently small physical dimensions

86 citations

Journal ArticleDOI
17 Aug 1989-Nature
TL;DR: In this paper, a series of experiments has been performed to determine whether nuclear fusion processes occur in palladium rods that have been electrochemically charged with deuterium, but no evidence has been obtained for any excess enthalpy, neutron, gamma ray, tritium or helium production during electrolysis of D_20 with palladium cathodes.
Abstract: A series of experiments has been performed to determine whether nuclear fusion processes occur in palladium rods that have been electrochemically charged with deuterium. With a variety of metallurgical pretreatment procedures and different electrolytes, no evidence has been obtained for any excess enthalpy, neutron, gamma ray, tritium or helium production during electrolysis of D_20 with palladium cathodes.

85 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
24 Oct 1991-Nature
TL;DR: In this article, the authors describe a photovoltaic cell, created from low-to medium-purity materials through low-cost processes, which exhibits a commercially realistic energy-conversion efficiency.
Abstract: THE large-scale use of photovoltaic devices for electricity generation is prohibitively expensive at present: generation from existing commercial devices costs about ten times more than conventional methods1. Here we describe a photovoltaic cell, created from low-to medium-purity materials through low-cost processes, which exhibits a commercially realistic energy-conversion efficiency. The device is based on a 10-µm-thick, optically transparent film of titanium dioxide particles a few nanometres in size, coated with a monolayer of a charge-transfer dye to sensitize the film for light harvesting. Because of the high surface area of the semiconductor film and the ideal spectral characteristics of the dye, the device harvests a high proportion of the incident solar energy flux (46%) and shows exceptionally high efficiencies for the conversion of incident photons to electrical current (more than 80%). The overall light-to-electric energy conversion yield is 7.1-7.9% in simulated solar light and 12% in diffuse daylight. The large current densities (greater than 12 mA cm-2) and exceptional stability (sustaining at least five million turnovers without decomposition), as well as the low cost, make practical applications feasible.

26,457 citations

28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
TL;DR: This critical review shows the basis of photocatalytic water splitting and experimental points, and surveys heterogeneous photocatalyst materials for water splitting into H2 and O2, and H2 or O2 evolution from an aqueous solution containing a sacrificial reagent.
Abstract: This critical review shows the basis of photocatalytic water splitting and experimental points, and surveys heterogeneous photocatalyst materials for water splitting into H2 and O2, and H2 or O2 evolution from an aqueous solution containing a sacrificial reagent Many oxides consisting of metal cations with d0 and d10 configurations, metal (oxy)sulfide and metal (oxy)nitride photocatalysts have been reported, especially during the latest decade The fruitful photocatalyst library gives important information on factors affecting photocatalytic performances and design of new materials Photocatalytic water splitting and H2 evolution using abundant compounds as electron donors are expected to contribute to construction of a clean and simple system for solar hydrogen production, and a solution of global energy and environmental issues in the future (361 references)

8,850 citations