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

In this work, well-defined gold nanodendrites were simply synthesized by one-step electrodeposition by applying a constant potential of -0.2 V for 900 s in 0.5 mol/L H2SO4 containing 7.5 x 10(-3) mol/L HAuCl4 and 0.15 mol/L L-asparagine, which were preferentially growing along the (1 1 1) 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 x 10(-8) mol/L to 9.975 x 10(-7) mol/L, along with a low detection limit of 7.2 x 10(-9) mol/L (S/N = 3). The as-developed method was successfully used to detect trace amounts of formaldehyde in indoor air. (C) 2014 Elsevier B.V. All rights reserved.