Аңдатпа
Copper (Cu) powder production, in a sulfuric acid (H2SO4) solution with titanium (Ti) ions, was studied by electrolysis, using Cu anodes.It was empirically proven that this process occurs by three different stage-based mechanisms that depend on the electrolyte composition and electrolysis conditions.The first mechanism occurs in a H2SO4 solution with Cu 2+ ions and Ti 4+ (tetravalent ions).Cu 2+ are cathodically reduced, forming Cu powder (CP), since the process occurs at current densities (J) lower than the limiting one.So, part of the current that would be consumed by the hydrogen ions (H + ) reduction reaction is spent to reduce Ti 4+ , which results in Ti 3+ (trivalent ions).These, in the cathode space, reduce Cu 2+ , which, simultaneously, regenerates Ti 4+ .Then, these diffuse and are again reduced at the cathode, and Ti 3+ are formed, reducing Cu 2+ , in a cyclic process that further increases CP production current efficiency (CE) at the near-cathode space, forming more dispersed particles.The second mechanism occurs in a H2SO4 solution with only Ti 4+ .During the electrochemical circuit current flow, the Cu anode is oxidized to form Cu 2+ , and Ti 4+ are reduced to Ti 3+ , on the cathode surface.Then, Cu 2+ and Ti 3+ , by diffusing the solution volume and meeting in the inter-electrode space, chemically interact with each other, due to the red-ox (reduction-oxidation) potential difference, forming a dispersed CP and Ti 4+ .These diffuse one more time, and are again reduced to Ti 3+ .These processes are cyclically repeated, i.e., Ti 4+ work as catalyst.The third mechanism takes place in H2SO4 with Ti 3+ .When the current flows through the electrolyte, the Cu anode is oxidized, forming Cu 2+, which are immediately reduced in the anode by Ti 3+ , producing CP.Ti 4+ are formed due to the red-ox reaction diffusion to the cathode, being reduced to Ti 3+ on its surface, which again interact with Cu, producing CP on the anode.Since, in all mechanisms (except the first), CP is not directly produced on the cathode surface, but in the inter-electrode space, further growth of Cu particles does not occur.Thus, CP particles of spherical shape, with sizes from 0.01 to 0.1 μm, are formed, with a CE from 95.2 to 99.1%, under optimal conditions.