Electrodeposition of ZnO from DMSO solution: influence of anion nature and its concentration in the nucleation and growth mechanisms

Abstract

A influência da natureza aniônica e sua concentração na eletrodeposição de ZnO em um eletrodo de ouro de soluções de dimetilsulfóxido (DMSO) foi estudada. Experimentos voltamétricos mostraram alterações importantes no processo de eletrodeposição de óxido de zinco dependendo do ânion empregado como eletrólito. A partir de experimentos de cronoamperometria, as correspondentes curvas corrente-tempo foram ajustadas com diferentes modelos de mecanismos de nucleação e crescimento. A análise destes resultados mostrou a mudança de um crescimento instantâneo para um progressivo quando a composição da solução foi mudada de ZnCl 2 para ZnCl 2 + LiCl. A modificação do mecanismo está associada à adsorção de íon cloreto nos sítios ativos da superfície do eletrodo quando LiCl está presente na solução.The influence of the anion nature and its concentration in the electrodeposition of ZnO onto a gold electrode from dimethylsulfoxide (DMSO) solutions was studied. Voltammetric experiments revealed important changes in the zinc oxide electrodeposition process depending on the employed anion as electrolyte. From chronoamperometric experiments, the corresponding current-time curves were fitted with different nucleation and growth mechanism models. The analysis of these results showed changes from an instantaneous to a progressive growth when the solution composition was changed from ZnCl 2 to ZnCl 2 + LiCl. The change of the mechanism is associated to the adsorption of chloride ion on the active sites of the electrode surface when LiCl is present in the solution.

EFFECT OF CHLORIDE IONS ON THE STRUCTURAL, OPTICAL, MORPHOLOGICAL, AND ELECTROCHEMICAL PROPERTIES OF Cu2O FILMS ELECTRODEPOSITED ON FLUORINE-DOPED TIN OXIDE SUBSTRATE FROM A DMSO SOLUTION

“…Numerous studies 11,[18][19][20][21][22] have shown that the electroreduction of molecular oxygen in DMSO is a monoelectronic transference followed by different chemical stages. When this process is carried out in presence of a metallic cation, a solid phase corresponding to the metallic oxide is formed.…”

“…Thus, the Cu 2 O electrodeposition from DMSO-chloride solutions shows better performance than those that derive from DMSO-perchlorate solutions. The effect of chloride ions on the oxide semiconductor electrodeposition process has been previously studied in both aqueous 12,23 and DMSO solutions 22 . In reference to these studies, it is a well known fact, that chloride ions in aqueous solutions dope ZnO films during their electrodeposition 12 .…”

“…In the latter chloride ions modify the morphology of the Cu 2 O films and lessen the structural quality as the chloride concentration increases. On the other hand, in a DMSO solution, chloride ions modify both the nucleation and growth mechanisms during the ZnO electrodeposition 22 . Here, the mechanism varies from instantaneous to progressive growth as a consequence of the complex formation between Zn(II) and chloride ions, and by the adsorption of these ions on the surface of the films.…”

Electrochemicaly formed ZnO and Au/ZnO opal films

“…Aqueous electrolytes are based on zinc chloride [4,7,15], sulfate [16], nitrate [17,18], or zinc acetate [19]. Nonaqueous electrolytes could be based on zinc chloride [20], nitrate [21] or perchlorate [20,22] with dimethylsulfoxide (DMSO), dimethylformamide (DMF) or hexamethyleneamine (HMT) as solvents. Despite all zinc chloride and zinc nitrate are commonly used as zinc precursors in electrolytes.…”

“…The electrochemical deposition of ZnO is available in different solvents to avoid hydration of zinc. Ethanol [27] and dimethyl sulfoxide (DMSO) [20,22,28] are promising solvents for electrolytes. The reaction mechanism involved in the electrochemical formation of a ZnO film in DMSO electrolytes is not based on hydroxide ions, and another recently reported mechanism may correspond to the presence of molecular oxygen as an oxidant [29].…”