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 H 2 SO 4 containing 7.5   ×   10 −3   mol/L HAuCl 4 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 HAuCl 4 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 −8   mol/L to 9.975   ×   10 −7   mol/L, along with a low detection limit of 7.2   ×   10 −9   mol/L ( S / N   =   3). The as-developed method was successfully used to detect trace amounts of formaldehyde in indoor air.