Deposition Time Effect of Photogrown and Photodecorated Ag Nanoparticles on ZnO Nanocolumns for SERS Substrates

Silver nanoparticles were deposited on ZnO nanocolumns (Ag-NP@ZnO-NC) by two different laser-assisted approaches: photodecoration method were separately the Ag NPs are synthesized and then deposited over ZnO NCs under a laser-irradiated solution and photogrowthing method which the Ag NPs were simultaneously photoreduced and photodeposited over the ZnO NCs. Irradiation time ranged between 15 and 60 min were studied. Surface-Enhanced Raman spectroscopy measurements of Ag-NP@ZnO-NC substrates were evaluated with Rhodamine 6G as an analyte. The size and density of AgNPs were affected the irradiation time.For photodecorated devices, the SERS intensity increases as the deposition time increases and for photogrown substrates, a contrary behavior was observed. Substrates manufactured by photogrowthing method were found as the best SERS substrates with a 5-fold times signal enhancement compared with devices obtained by photodecoration. Under the experimental optimized conditions is obtained with a limit of detection up to 10−6 M for Rhodamine 6G (R6G).