Kmno4

Electrodeposition of ZnMnO₃ was performed in a three–electrode cell. A ZnO nanowire electrode was used as the working electrode, a flat Pt spiral aligned parallel to the working electrode acted as the counter electrode and an Ag/AgCl (1 M KCl) electrode (PalmSens) was used as the reference electrode. A nitrogen (N₂ 5.0)–purged 0.175 mM KMnO₄ (Sigma Aldrich, purity≥99 %) aqueous solution (V=80 mL) was used as the precursor for ZnMnO₃ deposition. In a previous study, electrodeposition was performed in pure 0.175 mM KMnO₄ aqueous solution (pH 5.3±0.2) at a deposition potential E_Ag/AgCl=0.000 V.
^[31] (link) In this study, we adjusted the pH value of the precursor solution (to pH 4, pH 7 and pH 10, respectively) by adding KOH (Merck, EMSURE® for analysis) or HCl (Merck, 32 %). We adjusted the electrodeposition potential by ±0.059 V per pH unit (i. e. E_Ag/AgCl=0.033 V, −0.144 V and −0.321 V at pH 4, pH 7 and pH 10, respectively) to account for the pH‐dependent band alignment of metal oxide semiconductors. The electrodeposition time was set to 45 min in each case. The total charge passed during electrodeposition depends slightly on the pH value and accounts for 330±70 C g⁻¹ at pH 4, 280±50 C g⁻¹ at pH 7 and 470±60 C g⁻¹ at pH 4.

A SnCl₂ (5% w/v) solution was prepared from SnCl₂·2 H₂O (analytical grade, Merck, Darmstadt, Germany) in Milli-Q water containing 3 M H₂SO₄ (Merck, Darmstadt, Germany). A H₂SO₄ acid solution (0.1 M) was prepared from H₂SO₄ (Merck, Darmstadt, Germany) in Milli-Q water; a KMnO₄ solution (0.5% w/v) was prepared from KMnO₄ (analytical grade, Merck, Darmstadt, Germany) in Milli-Q water; and a NaOH solution (10 M) was prepared from NaOH (extra pure, Merck, Darmstadt, Germany) in Milli-Q water. The dicyandiamide monomer (99%) was purchased from Sigma-Aldrich. All other reagents are of analytical grade and used as supplied.