Regulating the Work Function of Cu2o Films Via Crystal Facet Engineering with Enhanced Charge Transfer and Sers Activity

Abstract

Semiconductors have been extensively studied for SERS application owing to the advantage of inexpensive, nontoxic and easy fabrication. However, the facile design of uniformity substrates with enhanced charge transfer and SERS activity are highly desirable. Herein, we reported the fabrication of Cu 2 O films with (100) and (111) facets exposed by adjusting the pH value of electrolyte. When using 4–NBT as probe molecule, the Cu 2 O(100) exhibits an improvement of enhancement factor about three times than Cu 2 O(111), as well as relatively low limit of detection up to 1  10 –7 M. All calculated relative standard deviation values are lower than 5%, which demonstrates the uniformity and reproducibility of as–prepared Cu 2 O film. UPS analysis reveals that (100) facet possesses lower electron work function, and can promote the efficient interfacial charge transfer. Furthermore, First–principles calculation confirmed that (100) facet possess the better adsorption ability for 4–NBT, which can transfer more electrons from Cu 2 O to the molecule due to its lower work function, and thus resulting in the remarkable improvement of SERS activity. This research will offer more choices for the design of uniformity semiconductor substrates with enhanced SERS sensitivity based on crystal facet engineering.

Keywords: Surface enhanced Raman scattering, Crystal facet engineering, Cuprous oxide, work function, Charge transfer