Cathodic electrodeposition of se on ti electrodes

Cathodic electrodeposition of mixed molybdenum–selenium oxides

“…5c support this theory. Previous reports have shown that Se 0 films deposited at room temperature are both amorphous and electronically insulating with an experimentally determined resistivity of 10 5 X cm [45]. This poor conductivity is consistent with the loss in current response seen in Fig.…”

“…The chronocoulometry response for deposition in 0.1 F Se IV O 2À 3 shows that the charge density initially increases over time at a rate of 1.7 mC s À1 cm À2 , but the signal abruptly plateaus after $30 s. This suggests an electrolysis reaction occurs that causes selenium to deposit onto ITO, but that the product is electronically passivating thereby preventing further reduction of Se IV O 2À 3 . Based on previous voltammetry studies at Au, Se 0 is the deposited phase, and its formation can be described by either a comproportionation reaction between Se IV and Se 2À intermediates [43,44] or the direct reduction of Se IV O 2À 3 [30,45,46]. By comparison, the chronocoulometry response for deposition from the mixed 0.05 F Mo, 0.05 F Se solution at À0.7 V maintains a linear slope of 2.9 mC s À1 cm À2 throughout the entire deposition process, suggesting that a different film composition results involving a mixture of molybdenum oxide with selenium.…”

“…At À1.3 V the film is less uniform, with cracks and pits clearly visible. These morphological differences can be attributed to competing side reactions such as decomposition [45] and gas evolution [52]. For example, deposited Se 0 can react with protons to form hydrogen selenide (i.e., Se 0 + 2-H + + 2e À ?…”

Nucleation and growth of selenium electrodeposition onto tin oxide electrode

“…There have been several previous studies of the electrodeposition of selenium films on different substrate surfaces [2,[4][5][6][7][8][9][10][11][12][13]. Those studies mainly focused on either the reduction pathway for Se(IV) [5,6,8,9,11], surface structures of Se atom layers [7,13], characterization of Se films [1,12] or the analysis of a trace amount of Se [9]. The investigation on initial stage of Se electrodeposition, including the nucleus formation and its growth mechanism, has not been reported.…”

Microgravimetric, rotating ring-disc and voltammetric studies of the underpotential deposition of selenium on polycrystalline platinum electrodes

“…In such applications, the cathodic reduction of selenious acid has been demonstrated to be the best way to obtain Se films either in the so-called metallic form (resistivity 1 X cm) or in the amorphous insulating form (resistivity 10 5 X cm) [1]. In this light, the study of the underpotential deposition of the first Se monolayer on Pt is a matter of relevance since it can provide a useful substrate for the further deposition of Cd, Zn, etc., even (in the case of monocrystalline substrates) in an epitaxial arrangement, as already proposed by Stickney and co-workers, in the so-called ECALE experiments [2][3][4].…”