The Chemistry of Cu₃N and Cu₃PdN Nanocrystals**

Abstract

The precursor conversion chemistry and surface chemistry of Cu 3 N and Cu 3 PdN nanocrystals are unknown or contested. Here, we first obtain phase-pure, colloidally stable nanocubes. Second, we elucidate the pathway by which copper(II) nitrate and oleylamine form Cu 3 N. We find that oleylamine is both a reductant and a nitrogen source. Oleylamine is oxidized by nitrate to a primary aldimine, which reacts further with excess oleylamine to a secondary aldimine, eliminating ammonia. Ammonia reacts with Cu I to form Cu 3 N. Third, we investigated the surface chemistry and find a mixed ligand shell of aliphatic amines and carboxylates (formed in situ). While the carboxylates appear tightly bound, the amines are easily desorbed from the surface. Finally, we show that doping with palladium decreases the band gap and the material becomes semi-metallic. These results bring insight into the chemistry of metal nitrides and might help the development of other metal nitride nanocrystals.

General Route to Colloidally Stable, Low-Dispersity Manganese-Based Ternary Spinel Oxide Nanocrystals

“…The carboxylic acid then undergoes condensation with an amine to form the observed amide. Alternatively, the imine (or aldehyde) could condense with another amine to produce the observed secondary imine product (Figure a,c, orange ). ,, Both mechanisms would also generate appreciable amounts of ammonia (Figure a, dark purple ), and this is evidenced by positive ammonia tests from a vessel containing DI water through which the reaction effluent gas was bubbled (Figure S19). Also, appreciable amounts of nitro-octane (Figure a, green ) are observed on the particle surface by FTIR (Figure S18, Table S3, N–O stretch ), , which we believe are derived from an alternative amine oxidation mechanism. , …”

“…The coprecipitation of nanocrystals and organic byproducts limits the purity of the nanocrystal product while providing little aid in colloidal stability. De Roo and co-workers 53,54 have also observed the formation of highmolecular-weight organic byproducts from nanocrystal syntheses containing amines, specifically the amide and imine byproducts which are especially difficult to purify during solvent/antisolvent washes. We hypothesized that using an amine with a shorter alkyl chain would allow for more facile purification of nanocrystals (Figures 5b and S20b) due to the lower hydrophobicity of its organic byproducts.…”

Coactivation of Multiphase Reactants for the Electrosynthesis of Urea

“…[36][37][38] Figure S4 (Supporting Information) provides the Auger electron spectroscopy of Cu, which in combination with the Cu 2p spectrum shows that: 934.6 and 954.7 eV peaks correspond to Cu 2p 2/3 and Cu 2p 1/2 , which are two characteristic peaks of Cu + (Figure 2c). [39] The appearance of a single peak at 398.7 eV indicates the presence of nitrogen in the nanoneedle array (Figure 2d). It is noteworthy that the N-H peak of V N -Cu 3 N-300 is lower relative to Cu 3 N, indicating an increase in nitrogen vacancies.…”

Solution-phase synthesis of group 3–5 transition metal chalcogenide inorganic nanomaterials

“…The possible decomposition pathways of the ligand must also be considered; even oleylamine can decompose to produce metal nitrides under some circumstances. 90 The use of solvents with saturated carbon chains, which tend to be more stable with respect to decomposition, and ligands with higher boiling points, should also be considered. 91…”