writer：Qian Cheng, Liping Song, Han Lin, Yanping Yang, Youju Huang*, Fengmei Su, and Tao Chen*
keywords：Janus Gold Nanoparticles Monolayer
source：期刊
specific source：Langmuir, 2020, 36, 250-256
Issue time：2020年

Large scaled two-dimensional free-standing monolayer ?lms of gold nanoparticles show distinctive optical, electrical, and chem-physical propertie making them a new class of advanced plasmonic materials di?ering from bulk materials and individual nanoparticles in solution. The conventional 2D gold nanoparticle ?lms usually possess symmetric structures and identical properties of gold nanoparticles on both sides. Herein, we developed an easy and e?cient approach to construct a new type of free-standing 2D gold nanoparticle monolayer ?lm with asymmetric gold nanoparticle structures and functions, called a 2D Janus gold nanoparticle ?lm. The remarkable feature of our method is the subsequent asymmetric growth on one side of the interfacial self-assembled gold nanoparticle monolayer ?lm at the air?liquid interface. It is very easy to control the morphology of the Janus ?lm by simply and precisely adjusting the size and shape of the gold nanoparticles on the top side, and selectively tuning the structure and composition on the bottom side of the ?lm by growing gold nanoparticles or other noble metals such as Ag, Pt, and Pd. Unlike the conventionally prepared Janus ?lms at solid substrate that require long-time etching and transfer procedures, other features of our method include the short time in which the interfacial self-assembly and the subsequent asymmetric growth are completed as well as the easily transferable property of the Janus ?lm onto di?erent substrates, such as quartz glass sheets, silicon wafers, and PDMS. The obtained Janus gold nanoparticle ?lm shows asymmetric wettabilities, optical properties, and surface-enhanced Raman scattering (SERS) e?ects, which is promising for a range of potential applications in optical devices, sensors, and asymmetric catalysis.