Effect of anions on electrodeposition of structured platinum nanocrystallites

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2020-12, Vol.878, p.114700, Article 114700
• Main Authors: Molodkina, Elena B., Ehrenburg, Maria R., Vysotskii, Vladimir V.
• Format: Article
• Language: English
• Subjects: Anions; Crystal defects; Crystallites; Cubic faceting; Effect of anions; Electrodeposition; Nanocrystals; Perchloric acid; Platinum; Platinum nanocrystallites; Single crystals; Structural selectivity; Sulfuric acid; Surface defects; Surface structure; Underpotential deposition
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2020.114700

Pulsed (square–wave) electrodeposition of platinum nanocrystallites with a high concentration of (100) regions from a H2PtCl6 solution with different background anions is studied. The effect of the background electrolyte is shown, namely, a more perfect cubic faceting of crystallites obtained in the 0.1 M HClO4 solution as compared to 0.5 M H2SO4. A procedure for deposit formation (secondary growth) with intermediate pulsed treatment in acid is suggested that does not involve application of high negative/positive overpotentials (no additional increasing of the mobility of platinum atoms). This allows preserving the crystallite structure and improving the overall deposit structure. In addition to conventional methods of fine surface structure determination on the basis of the hydrogen UPD region in cyclic voltammograms in sulfuric acid and SEM, we propose analysis of the Pt(100) terrace concentration/width based on the characteristic peak of nitrate ion reduction in voltammograms in perchloric acid. Stepped Pt single crystals with (100) terraces of different width are used for comparison. The effect of solution temperature on formation of faceted crystallites is shown and the optimum deposition temperature is determined: the optimum temperature in perchloric acid solution is 40 °C, while an increase in the temperature in sulfuric acid solutions results under the chosen conditions in deposition acceleration and an increase in the amount of surface defects. [Display omitted] •Strongly adsorbing anions distort the cubic shape of SWP-deposited Pt nanocrystallites due to the higher deposition rate.•Analysis of the amount and width of Pt(100) terraces by the nitrate reduction peak at ca. 0.33 V.•Existence of optimal temperature and optimal lower pulse potential for formation of nanocubes.•Discrepancy between the cubic crystallite shape and (100) signals in cyclic voltammograms.