Catalytic and SERS activities of WO₃-based nanowires: the effect of oxygen vacancies, silver nanoparticle doping, and the type of organic dye

Oxygen vacancies in tungsten trioxide (WO3) nanostructures (WO3-x) dominate the major characteristics of the material and determine their activity in various applications including photocatalysis and surface-enhanced Raman spectroscopy (SERS). Despite some studies performed in the last decade, the photocatalytic activity toward different pollutants and SERS activity toward different Raman reporter molecules are still unclear and may provide valuable insights into this research field. Therefore, in this study, we propose WO3-x nanowires (NWs) both as ideal photocatalysts for the degradation of organic pollutants such as crystal violet (CV), methylene blue (MB), malachite green (MG), and rhodamine 6G (R6G) and a SERS platform for the detection of these molecules. In the first step, WO3-x NWs were fabricated through the solvothermal method. Afterward, the oxygen vacancy content of WO3-x NWs was manipulated by the addition of silver ions or H2O2. Although H2O2 led to a remarkable decrease in oxygen vacancies (WO3), the addition of silver ions led to the formation of Ag nanostructures on WO3-x NWs (WO3-x@Ag). Interestingly, the combination of WO3-x and WO3-x@Ag nanosystems with all dye molecules resulted in the formation of H-aggregates due to the strong electrostatic interaction between the nanostructure and dye molecules and then its photocatalytic degradation, while regular degradation of dyes was observed for WO3. In SERS activity tests, each NP system exhibited different activities depending on various parameters including the chemical nature of the nanosystem, the degree of oxygen vacancy, the interaction of the Raman reporter molecule with the surface of the NP, and the resultant formation of H-aggregates or photocatalytic degradation. The combination of MB with WO3-x, WO3-x@Ag, and WO3 created enhancement factors such as 1.6 x 10(3), 5.4 x 10(3), and 6.2 x 10(3), respectively. This report showed that the parameters mentioned here must be considered in detail to evaluate the photocatalytic and SERS activity of the WO3-based nanosystem.

Journal

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

Year

2022

Volume

24

Issue

31

Pages

18615-18626

ISSN

1463-9076

eISSN

1463-9084

DOI

10.1039/d2cp00034b

WoS UID

WOS:000830667600001