Colloidal Synthesis of Tunable Copper Phosphide Nanocrystals

Abstract

Colloidal copper phosphide (Cu 3−x P) nanocrystals are attractive materials because of their ability to support excess delocalized holes, leading to localized surface plasmon resonance (LSPR) absorption in the near-IR. We present a one-pot, colloidal synthesis of Cu 3−x P nanoplatelets from copper halide salts and tris(diethylamino)phosphine [P(NEt 2 ) 3 ] in the presence of oleylamine (OAm) and trioctylamine. Mass spectrometry and nuclear magnetic resonance spectroscopy reveal that the formation of Cu 3−x P is accompanied by an aminophosphonium byproduct, suggesting that Cu 3−x P synthesis proceeds through a mechanism similar to that of other metal phosphide nanocrystals. The in situ copper−phosphorus precursor is identified by mass spectrometry, providing an insight into the prenucleation chemistry that was not possible in other aminophosphine-based metal phosphide syntheses. The final nanocrystal ensemble can be tuned by varying the precursor ratios (OAm/P(NEt 2 ) 3 or P(NEt 2 ) 3 /CuCl), copper halide (CuCl vs CuBr), or temperature, maintaining low polydispersity over a wide parameter space. By modulating the reactivity, the syntheses presented herein can be used to access nanocrystals with lateral sizes of 6.1−23 nm with LSPR energies of 709−861 meV. Overall, this synthesis presents a platform for systematic mechanistic investigations of the chemical processes underlying Cu 3−x P nanocrystal formation. The low polydispersity, size-and LSPR-tunability, and colloidal stability make these nanocrystals promising candidates for further investigations into factors governing the LSPR energy in Cu 3−x P nanomaterials.

Shape-Controlled Synthesis of Colloidal Nanorods and Nanoparticles of Barium Titanium Sulfide

“…These results are reminiscent of the properties of nanomaterials, such as copper sulfide, Cu 2– x S, and related materials, where off-stoichiometric compositions give rise to strong absorbance peaks in the visible-to-NIR regions which arise from localized surface plasmon resonances (LSPRs) due to the presence of free charge carriers (holes, in the case of Cu 2– x S). − It is possible that a similar phenomenon in BaTiS y is responsible for our observations, which would make BaTiS y a relatively rare example of a non-copper-containing chalcogenide nanocrystal exhibiting LSPR resonances; we do note that the observation of an LSPR absorbance in TiS 2 nanosheets has been proposed . The fact that the energy of the observed NIR absorbance peak increases with increasing off-stoichiometry would be consistent with this hypothesis.…”

Crystallize it before it diffuses: Kinetic stabilization of thin-film phosphorus-rich semiconductor CuP2

“…Cu 3 P is the most commonly reported binary stoichiometry in the Cu-P system. 5,6,26,27 Last, and most surprisingly, we find that highly Prich initial compositions do not help achieve a higher P content in the post-annealed films. In fact the opposite is true.…”

Two-dimensional copper based colloidal nanocrystals: synthesis and applications

“…Recently, Rachkov et al reported a colloidal synthesis of Cu 3− x P nanoplatelets from copper halide salts and tris(diethylamino)phosphine [P(NEt 2 ) 3 ] in a one-pot approach. 136 The mass spectrometry and nuclear magnetic resonance spectroscopy study revealed that aminophosphine is first transaminated with a long-chain primary amine. Then the aminophosphine-coordinated metal is disproportionated to give Cu 3− x P NCs along with some byproducts (Fig.…”