Highly Sensitive and Selective Formaldehyde Gas Sensors Based on Polyvinylpyrrolidone/Nitrogen-Doped Double-Walled Carbon Nanotubes.

A highly sensitive and selective formaldehyde sensor was successfully fabricated using hybrid materials of nitrogen-doped double-walled carbon nanotubes (N-DWCNTs) and polyvinylpyrrolidone (PVP). Double-walled carbon nanotubes (DWCNTs) and N-DWCNTs were produced by high-vacuum chemical vapor deposition using ethanol and benzylamine, respectively. Purified DWCNTs and N-DWCNTs were dropped separately onto the sensing substrate.

Magnetite nanoparticles decorated on multi-walled carbon nanotubes for removal of Cu from aqueous solution.

Acid-functionalized multi-walled carbon nanotube (MWCNTs-COOH) was prepared by acid treatment followed by decoration with magnetite (FeO) nanoparticles (FeO/MWCNTs-COOH) by co-precipitation of Fe/Fe in the colloidal suspension of MWCNTs-COOH. The adsorption capacity and separation efficiency of these two adsorbents were investigated for the removal of Cu ions in aqueous solution as water treatment adsorbents. The effect of reaction conditions, such as contact time, initial concentration of Cu ions, and adsorbent dosage, on the adsorption capacity of MWCNTs-COOH was investigated.

Prominent electronic and geometric modifications of palladium nanoparticles by polymer stabilizers for hydrogen production under ambient conditions.

A remarkable effect from the modification of electronic and geometric properties of Pd nanoparticles by the use of polymer pendant groups bound to the surface of palladium nanoparticles is reported. The degree of electron promotion to the Pd nanoparticles under ambient conditions was found to be dependent on the availability of the lone pair electrons of the pendant groups.

Electron promotion by surface functional groups of single wall carbon nanotubes to overlying metal particles in a fuel-cell catalyst.

A remarkable promotion: Functional groups added onto single-wall carbon nanotubes (SWNTs) can significantly influence the activity of a noble metal for formic acid oxidation. Phenolate groups on SWNTs under alkaline conditions can double the activity of 20 % w/w Pd compared to unmodified SWNTs. This catalyst has 14 times higher activity than the commercial benchmark catalyst (10 % w/w Pd on Vulcan).

Hydrogen production from formic acid decomposition at room temperature using a Ag-Pd core-shell nanocatalyst.

Formic acid (HCOOH) has great potential as an in situ source of hydrogen for fuel cells, because it offers high energy density, is non-toxic and can be safely handled in aqueous solution. So far, there has been a lack of solid catalysts that are sufficiently active and/or selective for hydrogen production from formic acid at room temperature. Here, we report that Ag nanoparticles coated with a thin layer of Pd atoms can significantly enhance the production of H₂ from formic acid at ambient temperature.

¹³C NMR guides rational design of nanocatalysts via chemisorption evaluation in liquid phase.

The search for more efficient heterogeneous catalysts remains critical to the chemical industry. The Sabatier principle of maximizing catalytic activity by optimizing the adsorption energy of the substrate molecule could offer pivotal guidance to otherwise random screenings. Here we show that the chemical shift value of an adsorbate (formic acid) on metal colloid catalysts measured by (13)C nuclear magnetic resonance (NMR) spectroscopy in aqueous suspension constitutes a simple experimental descriptor for adsorption strength.

Formate as a surface probe for ruthenium nanoparticles in solution 13C NMR spectroscopy.

Formic acid adsorption on ruthenium nanoparticles of different sizes allows differentiation of differently bound formate species by solution (13)C NMR spectroscopy (see picture). The chemical shifts are comparable to those of organometallic analogues, thus indicating that formate can act as a probe to distinguish surface features of metallic nanoparticles in solution with good quantification and resolution.