Ultrasmall Cu₃N Nanoparticles: Surfactant-Free Solution-Phase Synthesis, Nitridation Mechanism, and Application for Lithium Storage

New chemical pathways are of fundamental interest for materials synthesis. Here, we report a novel surfactant-free, solution-phase, low-temperature route to crystalline, ultrasmall (∼2 nm) Cu 3 N nanoparticles via a one-step reaction between copper(II) methoxide and benzylamine. We propose a reaction mechanism for Cu 3 N formation based on the gas chromatography–mass spectrometry (GC–MS) analysis of the organic reaction byproducts. The reaction pathway involves reduction of the Cu(II) to Cu(I) by benzylamine, in situ generation of ammonia, and finally, the reaction between Cu(I) and ammonia to form Cu 3 N. We tested the Cu 3 N nanoparticles as an anode material for Li-ion batteries (LIBs). According to cyclic voltammetry, the Cu 3 N nanoparticles quickly undergo a phase transformation to Cu 2 O, but then stably deliver a capacity of ∼290 mAh/g at 1 A/g in the following 150 cycles.