Nucleation and growth of silver nanostructures onto HOPG electrodes in the presence of picolinic acid

Monitoring of Silver Electrodeposition onto HOPG Electrodes in the Presence of Picolinic Acid by in Situ Surface-Enhanced Raman Spectra Measurements

“…The molecular structure and the stability constants of both [Ag(HPic)] + and [Ag(Pic)] complexes were established by analysis of nuclear magnetic resonance ( 1 H NMR) spectra at pH 3.0 and 6.5 as was described previously. 15 The comparative analysis of the spectra (results not shown) of the 5.0 mM PA solution after addition of different amounts of Ag + ions permitted us to establish that: (i) Both HPic and Pic − ligands interact with Ag + ions through the carboxylate group and (ii) the stability constants for 1:1 complexes, given by reactions 3 and 4.…”

“…The acidic–base functions of these molecules are given by three different species, depending on the solution pH, i.e., protonated, zwitterion, and anion. The influence of picolinic acid (PA) molecules on the nucleation and growth mechanism has been recently studied for copper and silver deposition. − The reported results have shown that PA species can be strongly adsorbed on the growing nuclei surface, thereby inhibiting the surface reactivity, and as a consequence, the crystallites grow as dendritic microstructures. Many SERS studies of adsorbed pyridine carboxylic acids on metal substrates have been mainly focused on the effect produced by changing the solution pH ,− and the applied potential, , whereas a few publications have been on in situ studies of the electrodeposition process, i.e., formation of a new phase with structures (SERS active sites) that induce preferential adsorption of the additive. ,− The aim of this study is the molecular tracking of the picolinic acid molecules during the silver particles electroformation onto HOPG by in situ Raman spectroscopy, under different experimental conditions.…”

Spectroelectrochemistry and photoelectrochemistry of electrodeposited ZnO nanorods

“…At more negative potentials there is a higher surface density of ZnO nanorods (see Figure S2) as there is an increase of the ITO nucleation active sites. 42 Samples prepared at -0.80 V are 700 nm diameter hexagonal columns, with typical wurtzite-type structures of ZnO, as can be confirmed by the presence of intense vibrational bands at 110 and 440 cm -1 (E2 low and E2 high, respectively) in the Raman spectra 43 and the corresponding peaks in the XRD patterns 16 (see Figure S3). The analysis of SEM images indicates that the more negative the applied potential the smaller the ZnO nanorods; they become pointier, and also lose the hexagonal shape.…”

“…As the deposition potential is more negative and the current is higher, the deposition process will be different. At more negative potentials there is a higher surface density of ZnO nanorods (see Figure S2) as there is an increase of the ITO nucleation active sites 42 . Samples prepared at ‐0.80 V are 700 nm diameter hexagonal columns, with typical wurtzite‐ type structures of ZnO, as can be confirmed by the presence of intense vibrational bands at 110 and 440 cm –1 (E2 low and E2 high, respectively) in the Raman spectra 43 and the corresponding peaks in the XRD patterns 16 (see Figure S3).…”

Electrode–Electrolyte Interfacial Processes in Ionic Liquids and Sensor Applications

“…The past decades have been characterized by a spectacular development of in situ techniques for studying interfacial processes at metal electrodes. Radioactive tracer [31,32], pulse potentiodynamic [33,34], and galvanostatic methods [35] have been applied quantitatively to study the adsorption of organic compounds at solid metals. In the study of complex electrode reactions, vibrational spectroscopies, such as Raman [36][37][38][39][40], the infrared (IR) [41][42][43], and UV-vis spectroscopies [44,45], have been used to identify adsorbed intermediates and the nature of the chemisorption bond [46].…”