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.

Synthesis, Characterization, and Reactivity of Ethynyl- and Propynyl-Terminated Si(111) Surfaces

Abstract: Ethynyl- and propynyl-terminated Si(111) surfaces synthesized using a two-step halogenation/alkylation method have been characterized by transmission infrared spectroscopy (TIRS), high-resolution electron energy-loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), atomic-force microscopy (AFM), electrochemical scanning–tunneling microscopy (EC-STM) and measurements of surface recombination velocities (S). For the ethynyl-terminated Si(111) surface, TIRS revealed signals corresponding to ethynyl ≡C–H and C≡C stretching oriented perpendicular to the surface, HREELS revealed a Si–C stretching signal, and XPS data showed the presence of C bound to Si with a fractional monolayer (ML) coverage (Φ) of ΦSi–CCH = 0.63 ± 0.08 ML. The ethynyl-terminated surfaces were also partially terminated by Si–OH groups (ΦSi–OH = 0.35 ± 0.03 ML) with limited formation of Si3+ and Si4+ oxides. For the propynyl-terminated Si(111) surface, TIRS revealed the presence of a (C–H)...

An Integrated, Systems Approach to the Development of Solar Fuel Generators

Abstract: 40% of current global transportation fuel is consumed in uses for which electrification is technically difficult, if not impossible, such as in heavy-duty trucks, ships, and aircraft.2 Exhaustive use of advanced biofuels might possibly supply adequate carbon-neutral transportation fuel for these uses, but could not then also fulfill the requirement for long term, massive, grid-scale energy storage.3 Chemical fuels are desirable for energy storage because fuels are the most energy-dense storage medium known to man (other than the atomic nucleus), and could simultaneously provide a means to baseload at scale intermittent renewable energy resources while also fulfilling gaps in the need for high energy-density, carbon neutral, sustainable, transportation fuels.4 Hence a clear rationale exists to

Phase Directing Ability of an Ionic Liquid Solvent for the Synthesis of HER-Active Ni2P Nanocrystals

Abstract: An ionic liquid (IL) solvent was used to synthesize small, phase-pure nickel phosphide (Ni2P) nanocrystals. In contrast, under analogous reaction conditions, substitution of the IL for the common high-boiling organic solvent 1-octadecene (ODE) results in phase-impure nanocrystals. The 5 nm Ni2P nanocrystals prepared in IL were electrocatalytically active toward the hydrogen evolution reaction. The synthesis in IL was also extended to alloyed Ni2–xCoxP nanocrystals, where 0.5 ≤ x ≤ 1.5.

Modeling and Simulation of the Spatial and Light-Intensity Dependence of Product Distributions in an Integrated Photoelectrochemical CO2 Reduction System

Abstract: A multiphysics model that accounts for the performance of electrocatalysts and triple-junction light absorbers, as well as for the transport properties of the electrolyte and dissolved CO2, was used to evaluate the spatial and light-intensity dependence of product distributions in an integrated photoelectrochemical CO2 reduction (CO2R) cell. Different sets of band gap combinations of triple-junction light absorbers were required to accommodate the optimal total operating current density relative to the optimal partial current density for CO2R. The simulated product distribution was highly nonuniform along the width of the electrode and depended on the electrode dimensions as well as the illumination intensity. To achieve the same product selectivity as in a potentiostatic, “half-cell” configuration, the electrocatalyst must retain its selectivity over a range of cathode potentials, and this range is dependent on the transport losses and current–voltage relationship of the light absorbers, the geometric pa...

I and i

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 …

A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films

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.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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。

Heterogeneous photocatalyst materials for water splitting

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)