Monoclinic Copper(I) Selenide Nanocrystals and Copper(I) Selenide/Palladium Heterostructures: Synthesis, Characterization, and Surface-Enhanced Raman Scattering Performance

Graphical Monoclinic Cu 2 Se nanocrystals and Cu 2 Se/Pd heterostructures have been synthesized by simple and facile methods. Owing to strong synergistic effects and phase-dependent characteristics, the surface-enhanced Raman scattering performance of the Cu 2 Se/Pd heterostructure is superior to those of Cu 2 Se, Pd, CuSe/Pd, and Cu 2– x Se/Pd. We have developed a simple and facile approach to the fabrication of monoclinic Cu 2 Se nanocrystals and Cu 2 Se/Pd heterostructures. [(C 2 H 5 ) 4 N] 2 [CuCl 4 ] was chosen as the copper source and SeO 2 /terpineol was used as the Se –II precursor for the generation of hexagonal CuSe and cubic Cu 2– x Se through the “hot-injection” and “one-pot” methods, respectively. Both CuSe and Cu 2– x Se could be further transformed into monoclinic Cu 2 Se through heat treatment with trioctylphosphine (TOP) at 220 °C. Cu 2 Se/Pd as well as CuSe/Pd and Cu 2– x Se/Pd were readily obtained by simply mixing copper selenides and Pd(NO 3 ) 2 in a 2-propanol solution. The Pd nanoparticles were distributed on the surface of the copper selenides. The effect of certain reaction parameters on the formation of copper selenides was studied. The amount of terpineol used played an important role in the phase-selective synthesis of CuSe and Cu 2– x Se. The surface-enhanced Raman scattering (SERS) performance of the heterostructures was investigated with 4-mercaptopyridine (4-Mpy) as a probe molecule. Owing to the strong synergistic effects between Cu 2 Se and Pd, Cu 2 Se/Pd showed greater SERS performance than pure Pd or Cu 2 Se. Moreover, compared to those of CuSe/Pd and Cu 2– x Se/Pd, Cu 2 Se/Pd exhibited the highest SERS sensitivity to 4-Mpy with a detection limit as low as 1.0 × 10 –9 M , which revealed its phase- and composition-dependent characteristics. This Cu 2 Se/Pd heterostructure exhibits potential applications in the chemical and biological sensing fields.