Figure 4.
Photocatalytic properties of Pt/Si/Ag heterostructure photodiodes. (a) Photocatalytic degradation of indigo carmine (IC) with 2 × 109 Pt/Si/Ag photodiodes dispersed in 10 ml of 0.5 mM IC aqueous solution. The degradation was characterized by the ratio of the remaining IC concentration to its original concentration. The circles represent the photodegradation reaction of IC without photodiodes. The squares represent the same photodegradation reaction of IC with photodiodes. (b) Photocatalytic stability of the Pt/Si/Ag photodiodes in the IC degradation reaction. The experiment is carried out with 2.0 × 107 diodes dispersed in 2 ml of 10 μM IC aqueous solution under natural sunlight irradiation during Los Angeles local time from 10:00 am to 6:00 pm. (c) Photodegradation of 4NP with 8 × 108 Pt/Si/Ag photodiodes dispersed in 10 ml of 0.25 mM 4NP aqueous solution. The degradation was characterized by the ratio of the remaining NP concentration to its original concentration. The circles represent the photodegradation reaction of 4NP without photodiodes. The squares represent the same photodegradation reaction of 4NP with photodiodes. (d) Hydrogen production based on oxidation of formic acid catalyzed by Pt/Si/Ag photodiodes.