Rujing Ban,Zhengyan Xu,Yang Yang,Dayong Fan,Huidan Lu,Yongping Liu
This work synthesized ultrathin 2D CdSe nanosheets by a facile solvothermal method. The morphology, structure, composition, and thermal stability of the samples were studied and analyzed using transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), infrared spectra (IR), and thermogravimetric (TG) methods. Results demonstrated that stable wurtzite-structured CdSe nanosheets with 2-3 nm thickness were successfully fabricated. UV-Vis absorption spectroscopy (UV-Vis) and fluorescence spectroscopy analysis exhibited the characteristic absorption peaks and fluorescence emission peaks of CdSe nanosheets with narrow full-width half-maximums (fwhm) and slight Stokes shift, implying ultrathin structure. Photoelectrochemical (PEC) measurement declared a fast and stable photo-response for the as-prepared CdSe ultrathin nanosheets. With the reaction temperature increasing, the PEC activity enhanced due to the decreased nanosheets thickness. This paper provides a new route for the synthesis of CdSe ultrathin nanosheets and their application in the field of photoelectrochemical catalysis.
Two-dimensional colloidal CdSe nanoplatelets (NPLs) have been considered as ideal emitting materials for high performance light-emitting devices due to their excellent optical properties. However, the understanding of defect related radiative and nonradiative recombination centers in CdSe NPLs is still far from sufficient, especially their physical distribution locations. In this work, CdSe core and CdSe/CdS core/crown NPLs have been successfully synthesized and their optical properties have been characterized by laser spectroscopies. It is found that the photoluminescence quantum yield of CdSe NPLs is improved by a factor of 4 after the growth of the CdS crown. At low temperatures, the change in the ratio of low and high energy emission intensities from NPLs suggests that the radiative recombination centers are mainly located on the lateral surface of the samples. This finding is further confirmed by the surface passivation experiment. Meanwhile, the nonradiative recombination centers of NPLs located on the lateral surface are also confirmed by ligand exchange. These results demonstrate the importance of understanding the optical properties of the lateral surface of NPLs, which are important for the design of material structures for optoelectronic applications.
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