The effect of anions on the anodic formation of copper sulphide films on copper

The nature of the copper sulfide film grown on copper in aqueous sulfide and chloride solutions

“…Although the location of the previously discussed base layer and its apparent thickness are indicated in Figure 8d, they are difficult to observe, owing to the presence of much larger features. The formation of such a thick crystalline outer deposit was consistent with our previous observations [ 6–15 ] and with our demonstration that growth of this deposit occurred at the film/solution interface, supported by the transport through the pores of the base layer of Cu(I), as both sulfide complexes (Cu(SH) 2 − ) and Cu 3 S 3 clusters, formed at the Cu surface. [ 15,24–29 ]…”

“…This decrease in plateau current density has been shown to be due to a competition between SH − and Cl − for adsorption sites on the Cu surface. [ 11 ] Although [SH − ] had been increased by an order of magnitude, the anodic current density remained the same on the reverse scan as it was on the forward scan, consistent with the presence of a porous film. [ 8 ] However, two cathodic reduction peaks were observed (regions C and D), suggesting the presence of either two distinct morphological forms of the same phase or, possibly, two different copper sulfide phases.…”

“…More comprehensive studies have shown that film growth is partially controlled by the SH − flux and partially by the interfacial kinetics. [ 9,11 ]…”

“…More comprehensive studies have shown that film growth is partially controlled by the SH − flux and partially by the interfacial kinetics. [9,11] Figure 5 shows the charges associated with the reduction peaks C and D, recorded as a function of the electrode rotation rate, in solutions containing a high [SH − ] and high [Cl − ]. Under stagnant conditions, the cathodic charge associated with peak D (Q D ) was negligible, suggesting that only film C was formed when the flux of SH − to the Cu surface was low.…”

“…Considerable effort has been expended on the investigation of the copper sulfide film formation process. [5][6][7][8][9][10][11][12][13][14][15] The physical properties of this chalcocite film have been demonstrated to vary significantly with sulfide concentration [SH − ], the flux of SH − to the Cu surface, and the presence of other groundwater anions (such as Cl − and SO 4…”