Fabrication of a new heterostructure Au/Pt/SnO2: An excellent catalyst for fast reduction of para-nitrophenol and visible light assisted photodegradation of dyes

Described here is a typical strategy to prepare Pt/SnO₂, Au/Pt/SnO₂ heterostructures on transparent conducting oxide (TCO, fluorine doped tin oxide, SnO₂: F, resistivity: 10–12 Ω²) substrates. Synthesized Au/Pt/SnO₂ heterostructure triggers nitrophenol reduction and enhances dye degradation under visible radiation. Bi-metallic system (Au and Pt), layer of active metal oxide (SnO₂) are introduced to speed up these applications. The reduction rate is fast and within 8 min it can reduce almost 100 % of para-nitrophenol. The decrease in band gap from 3.66 eV (for SnO₂) to 3.28 eV (for Au/Pt/SnO₂) ensures absorption of visible light which results enhanced photodegradation of Rhodamine B (RhB) and Congored (CR) dyes. Trapping experiments are performed by introducing scavengers to investigate the role of active species (OH, e⁻, h⁺, O₂⁻) involved in dye degradation. The effects of other parameters like pH, catalyst dosage and dye concentration are precisely investigated.