Large‐Scale Synthesis of Long Crystalline Cu_2‐xSe Nanowire Bundles by Water‐Evaporation‐Induced Self‐Assembly and Their Application in Gas Sensing

Abstract

Abstract By a facile water evaporation process without adding any directing agent, Cu 2‐x Se nanowire bundles with diameters of 100–300 nm and lengths up to hundreds of micrometers, which comprise crystalline nanowires with diameters of 5–8 nm, are obtained. Experiments reveal the initial formation/stacking of CuSe nanoplates and the subsequent transformation to the Cu 2‐x Se nanowire bundles. A water‐evaporation‐induced self‐assembly (WEISA) mechanism is proposed, which highlights the driving force of evaporation in promoting the nanoplate stacking, CuSe‐to‐Cu 2‐x Se transformation and the growth/bundling of the Cu 2‐x Se nanowires. The simplicity, benignancy, scalability, and high‐yield of the synthesis of this important nanowire material herald its numerous applications. As one example, the use of the Cu 2‐x Se nanowire bundles as a photoluminescence‐type sensor of humidity is demonstrated, which shows good sensitivity, ideal linearity, quick response/recovery and long lifetime in a very wide humidity range at room temperature.