Claire J. Carmalt

Robust self-cleaning surfaces that function when exposed to either air or oil

A robust paintlike repellent coating Superhydrophobic materials often depend on a particular surface patterning or an applied coating. However, these surfaces can be damaged by wear or fouled by oily materials. Lu et al. devised a suspension of coated titanium dioxide nanoparticles that can be spray-painted or dipcoated onto a range of hard and soft surfaces, including paper, cloth, and glass. The coatings resisted rubbing, scratching, and surface contamination. Science, this issue p. 1132 Robust, coated self-cleaning surfaces function after either abrasion or oil contamination. Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications.

Self-Driven One-Step Oil Removal from Oil Spill on Water via Selective-Wettability Steel Mesh

Marine oil spills seriously endanger sea ecosystems and coastal environments, resulting in a loss of energy resources. Environmental and economic demands emphasize the need for new methods of effectively separating oil-water mixtures, while collecting oil content at the same time. A new surface-tension-driven, gravity-assisted, one-step, oil-water separation method is presented for sustained filtration and collection of oil from a floating spill. A benchtop prototype oil collection device uses selective-wettability (superhydrophobic and superoleophilic) stainless steel mesh that attracts the floating oil, simultaneously separating it from water and collecting it in a container, requiring no preseparation pumping or pouring. The collection efficiencies for oils with wide ranging kinematic viscosities (0.32-70.4 cSt at 40 °C) are above 94%, including motor oil and heavy mineral oil. The prototype device showed high stability and functionality over repeated use, and can be easily scaled for efficient cleanup of large oil spills on seawater. In addition, a brief consolidation of separation requirements for oil-water mixtures of various oil densities is presented to demonstrate the versatility of the material system developed herein.

Gas sensing with nano-indium oxides (In2O3) prepared via continuous hydrothermal flow synthesis.

A rapid, clean, and continuous hydrothermal route to the synthesis of ca. 14 nm indium oxide (In(2)O(3)) nanoparticles using a superheated water flow at 400 °C and 24.1 MPa as a crystallizing medium and reagent is described. Powder X-ray diffraction (XRD) of the particles revealed that they were highly crystalline despite their very short time under hydrothermal flow conditions. Gas sensing substrates were prepared from an In(2)O(3) suspension via drop-coating, and their gas sensing properties were tested for response to butane, ethanol, CO, ammonia, and NO(2) gases. The sensors showed excellent selectivity toward ethanol, giving a response of 18-20 ppm.

Creating superhydrophobic mild steel surfaces for water proofing and oil-water separation

A simple and inexpensive two-step immersion method is reported to make mild steel superhydrophobic. Micro–nano-scale roughness and surface chemistry modifications were created via immersing mild steel into a salt solution followed by treatment with a low surface-energy polymer. The fabricated mild steel has water contact angles greater than 150° and remarkable water bouncing properties. This method was also used to treat a mild steel mesh for oil–water separation. In this paper, a new, facile and reusable gravity-induced separation system is proposed to collect floating oil, the oil collection rate can reach >96%.

Atmospheric pressure chemical vapor deposition of WSe2 thin films on glass : highly hydrophobic sticky surfaces

Atmospheric pressure chemical vapour deposition (APCVD) of tungsten selenide films on glass substrates was achieved by reaction of diethyl selenide with WCl6 at 500–650 °C. X-Ray diffraction showed that the WSe2 films were crystalline with cell constants close to those expected—some preferred orientation was noted at higher deposition temperature. Energy-dispersive analysis by X-rays (EDAX) gave a W ∶ Se ratio close to 1 ∶ 2 for all the films formed at 550 °C. The films were matt black in appearance, were adhesive, passed the Scotch tape test but could be scratched with a steel scalpel. SEM showed that the films were composed of either plate or needle like crystals which become longer and thicker with increasing deposition temperature. The films were highly hydrophobic with contact angles for water droplets in the range of 135–145°. Furthermore these surfaces were highly adherent for water droplets—that did not roll or slide even at a tilt angle of 90°.

The reactions of stable nucleophilic carbenes with main group compounds

Publisher Summary This chapter discusses various reactions of stable nucleophilic carbenes with main group compounds. Special interest is associated with carbenes that feature the attachment of donor groups to the carbenic carbon as they behave as nucleophiles and, in some instances, can be isolated. Stable nucleophilic carbenes that are capable of forming isolable complexes with a variety of main group species in oxidation states ranging from +1 to +6. The majority of the complexes that have been reported thus far possess 1:1 stoichiometry; however, there are several instances of 2:1 complexation and one example of a 3:1 complex. Although, in principle, it is possible to write double-bonded (carbene)CuEXn canonical forms to describe the interactions between carbenes and main group entities (EXn), in the stable nucleophilic carbene complexes the bonding is predominantly of the donor–acceptor type—namely (carbene)C→EX n . As such, the chemistry of these two-electron donor carbenes bears a strong-resemblance to that of electron-rich phosphines.

Tungsten Doped TiO2 with Enhanced Photocatalytic and Optoelectrical Properties via Aerosol Assisted Chemical Vapor Deposition.

Tungsten doped titanium dioxide films with both transparent conducting oxide (TCO) and photocatalytic properties were produced via aerosol-assisted chemical vapor deposition of titanium ethoxide and dopant concentrations of tungsten ethoxide at 500 °C from a toluene solution. The films were anatase TiO2, with good n-type electrical conductivities as determined via Hall effect measurements. The film doped with 2.25 at.% W showed the lowest resistivity at 0.034 Ω.cm and respectable charge carrier mobility (14.9 cm3/V.s) and concentration (×1019 cm−3). XPS indicated the presence of both W6+ and W4+ in the TiO2 matrix, with the substitutional doping of W4+ inducing an expansion of the anatase unit cell as determined by XRD. The films also showed good photocatalytic activity under UV-light illumination, with degradation of resazurin redox dye at a higher rate than with undoped TiO2.

Atmospheric pressure chemical vapour deposition of WS2 thin films on glass

The atmospheric pressure chemical vapour deposition reaction Of W(CO)(6), WOCl4 or WCl6 with HS(CH2)(2)SH or HSC(CH3)(3) at 350-600degreesC leads to thin films Of WS2 on glass substrates. The WS2 films were nanocrystalline, showed a W:S ratio of 1:2 by EDAX and gave Raman bands at 416 and 351 cm(-1). The films were silver or gold in colour, adhesive to the substrate and showed Volmer-Webber type growth by SEM. Optical band gaps were 1.4 eV. The films were reflective in the visible region and transparent in the near IR

n-Type doped transparent conducting binary oxides: an overview

This article focuses on n-type doped transparent conducting binary oxides – namely, those with the general formula MxOy:D, where MxOy is the host oxide material and D is the dopant element. Such materials are of great industrial importance in modern materials chemistry. In particular, there is a focus on the search for alternatives to indium-based materials, prompted by indiums problematic supply risk as well as a number of functional factors. The important relationship between computational study and experimental observation is explored, and an extensive comparison is made between the electrical properties of a number of the most interesting experimentally-prepared materials. In writing this article, we aim to provide both an accessible tutorial of the physical descriptions of transparent conducting oxides, and an up-to-date overview of the field, with a brief history, some key accomplishments from the past few decades, the current state of the field as well as postulation on some likely future developments.

Designing durable and flexible superhydrophobic coatings and its application in oil purification

Lotus-inspired superhydrophobic coatings are usually mechanically weak and lack durability, this hinders their practical applications. A suspension that can be treated on various materials in any size and shape to form a mechanically durable superhydrophobic coating is developed, which retains water repellent properties after multiple cycles of abrasion, blade scratching, tape-peeling, repeated deformation, a series of environmental tests and recycling. Based on its superhydrophobicity under oil, two highly efficient systems were developed for oil purification – stirring and inverted cone systems. Small water drops converge on the coated surface that was immersed in oil through velocity-controlled stirring, or designing an inverted cone superhydrophobic surface under oil to collect water drops spontaneously. This coating can be readily used for practical applications to make a durable superhydrophobic coating that functions either in air or oils.