Figure 4.

Schematic diagram illustrating the most plausible charge-transfer and photocatalytic mechanisms in the metal/p-type semiconductor Ag-CuO hybrids: (a) If the LED excitation wavelength is larger than the energy band gap of CuO, electrons from the valence band can be excited to the conduction of CuO and subsequently transferred and trapped by Ag energy levels; (b) Ag plasmon-induced charge transfer by hot holes injection into the p-type CuO energy levels.