Shaped-controlled electrosynthesis of gold nanodendrites for highly selective and sensitive SERS detection of formaldehyde

Abstract

In this work, well-defined gold nanodendrites were simply synthesized by one-step electrodeposition by applying a constant potential of −0.2V for 900s in 0.5mol/L H2SO4 containing 7.5×10−3mol/L HAuCl4 and 0.15mol/L l-asparagine, which were preferentially growing along the (111) directions. It was found that the morphology of the Au deposits was strongly dependent on the applied potential, deposition time, and the molar ratio of HAuCl4 to l-asparagine. The as-prepared Au dendrites were used as highly Raman-active substrates for highly selective and sensitive detection of formaldehyde based on its reaction with 4-amino-3-hydrazino-5-mercapto-1, 2, 4-triazol (AHMT). The formaldehyde sensor displayed a wide linear range from 8.32×10−8mol/L to 9.975×10−7mol/L, along with a low detection limit of 7.2×10−9mol/L (S/N=3). The as-developed method was successfully used to detect trace amounts of formaldehyde in indoor air.