Pt(0) microscrolls obtained on nickel surface by galvanic replacement reaction in H$_2$PtCl$_6$ solution as the basis for creating new SERS substrates

The paper explores the morphology features of Pt(0) nanolayers obtained on the surface of chemically polished nickel as a result of the galvanic replacement reaction using H$_2$PtCl$_6$ solution. In a series of samples synthesized at a treatment time of 1–60 minutes, it is shown that the nanolayers consist of Pt(0) nanocrystals 5–10 nm in size, which form a continuous porous layer with a thickness depending on the treatment time in solution. For example, it is about 80 nm and 120 nm for samples obtained after 3 minutes and 20 minutes, respectively. Moreover, on the outer side of the nanolayer with respect to the substrate, these nanocrystals form arrays of pointed agglomerates directed along the normal to the surface. After drying in air, the Pt(0) nanolayer cracks and partially folded microscrolls form on the nickel surface, the number of which is the largest for the samples obtained with a longer treatment time. The features of the practical application of these samples as SERS substrates are studied using the Raman spectra of Rodamin 6G as an example. It is shown that the amplification factor is about 10$^5$–10$^6$ using 532 nm laser excitation.