Atom transfer radical polymerization is a versatile technique for exerting precise control over polymer molecular weights, weight distributions, and complex architectures. Here, we show that an externally applied electrochemical potential can reversibly activate the copper catalyst this process by one-electron reduction of initially added air-stable cupric species (Cu(II)/Ligand). Modulation kinetics thereby tunable in real time varying magnitude potential. Application multistep intermittent...

The electrochemical instability of semiconductors in aqueous electrolytes has impeded the development robust sunlight-driven water-splitting systems. We review use protective thin films to improve stability otherwise unstable semiconductor photoelectrodes (e.g., Si and GaAs). first discuss origins various strategies for achieving stable functional photoelectrosynthetic interfaces. then focus specifically on photoanodes photocathodes photosynthetic reactions that include oxygen evolution,...

Photoelectrochemical (PEC) water splitting has received growing attention as a potential pathway to replace fossil fuels and produce clean, renewable, sustainable source of fuel. To achieve overall the associated production solar fuels, complex devices are needed efficiently capture light from sun, separate photogenerated charges, catalyze reduction oxidation reactions. date, highest performing rely on multi-component systems, which introduce interfaces that can be with further performance...

Thin (10 nm) films of manganese oxide have been deposited by atomic layer deposition (ALD) onto n-type silicon and degenerately doped p-type silicon. The photoelectrochemical properties the resulting semiconductor/metal-oxide structures were evaluated in contact with aqueous 0.35 M K4Fe(CN)6–0.05 K3Fe(CN)6, 1.0 KOH(aq), as well a series nonaqueous one-electron, reversible, outer-sphere redox systems. Under simulated air mass (AM) 1.5 illumination K3Fe(CN)6(aq), MnO-coated n-Si photoanodes...

This work demonstrates the role of microstructure in friction and oxidation behavior lamellar solid lubricant molybdenum disulfide (MoS2). We report on systematic investigations for two MoS2 films with distinctively different microstructures—amorphous planar/highly-ordered—before after exposure to atomic oxygen (AO) high-temperature (250 °C) molecular oxygen. A combination experimental tribology, dynamics simulations, X-ray photoelectron spectroscopy (XPS), high-sensitivity low-energy ion...

We present a simple, solution-based synthetic route to hollow cerium oxide spheres. Thin layers (∼12 nm) of are deposited onto ∼200 nm silica colloids using nitrate and the cores subsequently removed yield The spheres composed ∼4 ceria nanocrystals. Nitrogen adsorption isotherms indicate that microporous with pore sizes approximately 10 Å. thermally stable collapse ripening up 700 °C active for catalytic combustion carbons. developed in this work attractive as building blocks multicomponent...

Thin films formed by atomic layer deposition (ALD) are being examined for a variety of chemical protection and diffusion barrier applications, yet their stability in various fluid environments is not well characterized. The titania alumina thin air, 18 MΩ water, 1 M KCl, HNO3, H2SO4, HCl, KOH, mercury was studied. Films were deposited at 150 °C using trimethylaluminum–H2O tetrakis(dimethylamido)titanium–H2O chemistries titania, respectively. A subset samples heated to 450 900 inert...

We report the molecular beam epitaxy growth of Al0.3Ga0.7As∕GaAs multijunction solar cells with epitaxial, semimetallic ErAs nanoparticles at interface tunnel junction. The states provided by these reduce bias required to pass current through junction three orders magnitude, and therefore drastically voltage losses in have measured open-circuit voltages which are 97% sum constituent cells, result nearly double efficiency our cell a conventional

We examined mesoporous TiO(2) as a photosensitizer and template for creating hybrid TiO(2)-polypyrrole materials. Optical excitation of was used to generate the electronic potential necessary oxidation polymerization pyrrole monomer. The photopolymerization process monitored by quartz crystal microbalance, nitrogen sorption, thermogravimetric techniques. In situ generation polypyrrole observed be self-limiting after approximately 20-30% filling network. complementary phase means charge...

The photoelectrochemical behavior of methyl-terminated p-type and n-type Si(111) surfaces was determined in contact with a series one-electron, outer-sphere, redox couples that span >1 V the Nernstian potential, E(A/A–), solution. dependence current vs potential data, as well open-circuit photovoltage, Voc, on E(A/A–) compared to H-terminated these same electrolytes. For particular value, CH3-terminated p-Si(111) electrodes showed lower Voc values than electrodes, whereas n-Si(111) higher...

The behavior of graphene-coated n-type Si(111) photoanodes was compared to the H-terminated in contact with aqueous K3[Fe(CN)6]/K4[Fe(CN)6] as well a series outer-sphere, one-electron redox couples nonaqueous electrolytes. n-Si/Graphene electrodes exhibited stable short-circuit photocurrent densities over 10 mA cm(-2) for >1000 s continuous operation electrolytes, whereas n-Si-H yielded nearly complete decay current density within ~100 s. values open-circuit photovoltages and flat-band...

Aluminum oxide thin films fabricated via atomic layer deposition are introduced as passivating tunneling interlayers between hole-selective molybdenum contacts and silicon absorbers. Surface recombination velocity specific contact resistivity reported a function of Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thickness. The effects substrate chemical pretreatment, the thermal...

Owing to the small energy differences between its polymorphs, MoTe2 can access a full spectrum of electronic states, from 2H semiconducting state 1T semimetallic state, and Td Weyl superconducting in phase at low temperature. Thus, it is model system for transformation studies as well quantum phenomena such spin Hall effect topological superconductivity. Careful potential applications require large area thin films with high crystallinity thickness control. Here, we present cm2 scale...

For decades, density has been attributed as a critical aspect of the structure sputter-deposited nanocrystalline molybdenum disulfide (MoS2) coatings impacting oxidation resistance and wear resistance. Despite its importance, there are few examples in literature that explicitly investigate relationship between behaviors MoS2 coatings. Aging primary considerations for use aerospace applications they inevitably experience prolonged storage water oxygen-rich environments prior to use. Oxidation...

The development of one- and two-photon induced polymerization using CdS semiconductor quantum dots (QDs) amine co-initiators to promote radical generation subsequent is presented. Two-photon absorption (TPA) cross-section measurements, linear absorption, transmission electron microscopy are used characterize the QDs. effectiveness in increasing efficiency photopolymerization (polymer chains formed per excitation) examined. Triethylamine was observed be most effective, yielding efficiencies...

Porous silica materials are attractive for hemorrhage control because of their blood clot promoting surface chemistry, the wide variety topologies and porous structures that can be created, potential ability to achieve high loading therapeutic proteins within support. We show cell-window size variation in nanometers tens range greatly affects rate at which clots formed human plasma, indicating window sizes this directly impact accessibility diffusion clotting-promoting from interior surfaces...

Abstract Gallium phosphide exhibits a short diffusion length relative to its optical absorption length, and is thus candidate for use in wire array geometries that allow light be decoupled from minority carrier collection. Herein reported the photoanodic performance of heteroepitaxially grown gallium on planar microwire‐array Si substrates. The n‐GaP|n‐Si heterojunction results favorable conduction band alignment electron collection silicon. A conformal electrochemical contact outer GaP...

Wafer-scale fabrication of PtSe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> MOSFETs was demonstrated by photolithography on Pt films directly selenized at 400 °C. Taking advantage the unique property to transition from a semiconductor semimetal as its thickness increases beyond few monolayers, channel recess adapted for improving gate control while keeping contact resistance below 0.01 Ω · cm. The wafer-scale resulted in uniform...

Abstract Pure molybdenum disulfide (MoS 2 ) solid lubricant coatings could attain densities comparable to doped films (and the associated benefits wear rate and environmental stability) through manipulation of microstructure via deposition parameters. Unfortunately, pure can exhibit highly variable microstructures mechanical properties due processes that are not controlled during (i.e., batch-to-batch variation). This work focuses on developing a relationship between density, hardness,...

Thin films of niobium nitride are useful for their physical, chemical, and electrical properties. NbN superconducting properties have been utilized in a wide range applications. Plasma-enhanced atomic layer deposition (PEALD) with (t-butylimido) tris(diethylamido) niobium(V) remote H2/N2 plasmas has investigated. Deposited film studied as function substrate temperature (100–300 °C), plasma power (150–300 W), H2 flow rate (10–80 sccm). PEALD were characterized spectroscopic ellipsometry...