One-pot synthesis of roxbyite Cu1.81S triangular nanoplates relevant to plasmonic sensor

Copper deficient Cu2-xS nanocrystals (NCs) exhibit localized surface plasmon resonance (LSPR) in near-infrared (NIR) wavelengths. For plasmonic applications, accurate control of their morphology and crystal phase which affect the LSPR wavelength and amplitude of Cu2-xS NCs has been one of the major challenges. Here, we demonstrate the effects of the reaction temperature and the concentration of sulfur source on the formation of triclinic roxbyite Cu1.81S triangular nanoplates (TNPs). As a potential plasmonic sensor in NIR region, the sensitivity factor (SF) and figure of the merit (FOM) of the Cu1.81S TNPs were calculated. The FOM of the Cu1.81S TNPs is slightly better than other samples synthesized in different reaction conditions, and it is comparable to gold nanospheres. In addition, the strong LSPR is stable and cannot be deracinated by thiol reduction, which is crucial for sensors in reductive environments. As a result, the strong LSPR quenched the photoluminescence of the Cu1.81S TNPs. Our method may provide a simple and versatile way to synthesize shaped Cu2-xS and other metal sulfide NCs for plasmonic sensing and other relevant applications.