Copper Selenophosphate, Cu₃PSe₄, Nanoparticle Synthesis: Octadecane Is the Key to a Simplified, Atom-Economical...

Nanoparticle syntheses are designed to produce the desired product in high yield but traditionally neglect atom-economy. Here we report that the simple, but significant, change of the solvent from 1-octadecene (1-ODE) to the operationally inert octadecane (ODA) permits an atom-economical synthesis of copper selenophosphate (Cu₃PSe₄) nanoparticles. This change eliminates the competing selenium (Se) delivery pathways from our first report that required an excess of Se. Instead Se⁰_powder is dispersed in ODA, which promotes a formal eight-electron transfer between Cu_3-P and Se⁰. Powder X-ray diffraction and transmission electron microscopy confirm the purity of the Cu₃PSe₄, while ¹H and ¹³C NMR indicate the absence of oxidized ODA or Se species. We utilize the direct pathway to gain insights into stoichiometry and ligand identity using thermogravimetric analysis and X-ray photoelectron spectroscopy. Given the prevalence of 1-ODE in nanoparticle synthesis, this approach could be applied to other chalcogenide reaction pathways to improve stoichiometry and atom-economy.