Vertically aligned single-crystalline ultra-thin CuO nanosheets: Low-temperature fabrication, growth mechanism, and excellent field emission

An effective and one-step solvothermal process is developed to fabricate vertically aligned ultra-thin CuO nanosheets with high-quality single crystalline structure on Cu substrate at low temperature of 90 °C. The thickness and size of the prepared nanosheets can be tailored by changing reaction duration and temperature. On the basis of experimental results, a possible mechanism for the formation of the vertically aligned ultra-thin CuO nanosheets is speculated. Moreover, the prepared ultra-thin CuO nanosheets exhibit excellent field emission (FE) properties, a low turn-on electric field of 2.19 V/μm and a high current density of 4.5 mA/cm2 at 8.23 V/μm can be realized from the optimized sample. More importantly, the optimized sample also shows excellent FE stability with fluctuations within 2%. Based on temperature-dependent FE measurement, the stable FE property can be attributed to the low local heating effects of sheet-like CuO emitters, originating from their superior heat dissipation ability and low Joule heating.