CuO/Cu2O‐Coated Cu2S Nanowire Arrays: Effects of Thermal Annealing on Thermal Stability and Optical Properties

Abstract CuO/Cu 2 O‐coated Cu 2 S nanowire arrays with an average diameter of 180 and 280 nm are prepared by the solid–gas reaction. The crystallinity of the oxide improves with increasing annealing temperature from 100 to 500 °C, whereas the melting point of the Cu 2 S nanowire arrays decreases with decreasing nanowire diameter (always less than that of bulk Cu 2 S, 1100 °C). The annealing temperature should be less than 500 °C for oxide‐coated Cu 2 S nanowire arrays that have an average diameter less than 180 nm, but can reach 500 °C for nanowire arrays that have an average diameter greater than 280 nm. Thermal annealing can improve the crystallinity of the oxide and optimize the optical properties of oxide‐coated Cu 2 S nanowire arrays. This research lays a foundation for direct application of CuO/Cu 2 O‐coated Cu 2 S nanowire arrays in photovoltaic and lithium‐ion batteries.