Cross-linked single-walled carbon nanotube aerogel electrodes via reductive coupling chemistry

Single-walled carbon nanotube (SWCNT) anions can be cross-linked by a dielectrophile to form covalent, carbon-bonded organogels. Freeze-drying produces cryogels with low density (2.3 mg cm−3), high surface area (766 m2 g−1), and high conductivity (9.4 S m−1), showing promise as supercapacitor electrodes. Counterion concentration controls debundling, grafting ratio, as well as all the resulting properties

Chemical Vapor Deposition Synthesis and Optical Properties of Nb2O5 thin films with Hybrid Functional Theoretical Insight into Band Structure and Band Gaps

Nb2O5 is an important material able to exist in many polymorphs with unique optical properties and morphologies that are dependent on the synthetic route. Here we report a novel ambient-pressure chemical vapor deposition route to Nb2O5 via aerosol-assisted chemical vapor deposition. The amorphous as-deposited films were annealed in air to obtain the the three most stable crystal structures: orthorhombic, tetragonal, and monoclinic. The films were thoroughly characterized for their material properties, and an in-depth study into the optical properties was carried out using state-of-the-art hybrid functional theory that allowed more insight into the optical properties of the materials

Ultraviolet Radiation Induced Dopant Loss in a TiO2 Photocatalyst

Doped TiO2 has been studied with intense interest in recent decades because of its ability to utilize visible wavelengths and enhance the efficiency of photocatalytic processes. Thus, as a class of materials, it is of significant interest for use in environmental ambient energy utilization applications. Using a popular and well-studied form of doped TiO2 (nitrogen doped) as an example, we show how 28 days of UVA irradiation which is identical in intensity with solar conditions is sufficient to cause the UV induced surface segregation and eventual loss of nitrogen dopant species in TiO2. This is evidenced by X-ray photoelectron spectroscopy and transient absorption spectroscopy. The loss of interstitial nitrogen dopants correlates with the eventual permanent loss of photocatalytic activity and visible light absorption. The UV induced loss of dopants in a metal oxide is unprecedented and represents a potential problem where the environmental use of doped metal oxides in applications is concerned