Phase-transformation of hexagonal Cu<sub>2</sub>S microplates to nanoparticle-confined Cu<sub>2</sub>O microplates at low temperatures and their electro-catalytic property for methanol oxidation

Abstract

The direct phase transformation of hexagonal Cu2S microplates to those that are S-included Cu2O was induced by low-temperature annealing at 200 degrees C under ambient conditions. The Cu2O microplates showed a nanoparticle-confined structure, which continued to have the hexagonal framework of the original Cu2S microplates. The compositional distributions, sizes, structures, and optical properties of the synthesized Cu2S and S-included Cu2O microplates were characterized. The S-included Cu2O microplates prepared via low-temperature annealing at 200 degrees C for 12 h (Cu2S-Cu2O-12 h), 24 h (Cu2S-Cu2O-24 h), and 48 h (Cu2S-Cu2O-48 h) showed electro-catalytic activities for methanol oxidation. The Cu2S-Cu2O-24 h microplates showed the best electro-catalytic activity and long-term stability.