Fig. 1. (a) Schematic diagram for the formation of the semiconductor shell on AuNPs. (b) Cyclic voltammograms of AuNPs modified ITO electrodes in pure pH = 3 H₂SO₄ (black curve), and containing 0.1 M CdCl₂ (red curve), 0.01 M Na₂S₂O₃ (blue curve), and 0.1 M CdCl₂ and 0.01 M Na₂S₂O₃ (purple curve), scan rate: 50 mV s^–1. (c) Dark field images of AuNPs before and after chronoamperometry at –0.8 V (vs. Pt quasi-reference) in pure pH = 3 H₂SO₄ (I), and containing 0.1 M CdCl₂ (II), 0.01 M Na₂S₂O₃ (III), and 0.1 M CdCl₂ and 0.01 M Na₂S₂O₃ (IV) for 8 min (scale bar: 2 μm).