Vanadium–oxygen species are very harmful to the environment and human health, and also some vanadium–oxygen species have good biological and biomedical effects to human beings. Thus, the study of vanadium–oxygen species is very significant. The types of V–O species are very complex. So far, however, the various structures of V–O species cannot be identified clearly. In this work, the surface‐enhanced Raman spectroscopy (SERS) was used to study vanadium–oxygen species in aqueous solution directly. The SERS spectra with high enhancement factor (EF) and detail information were obtained by the enhancement substrates such as gold nanoparticles (AuNPs), Ag mirror, the Au‐deposited Pt electrodes, and rough Au electrodes. The structures of vanadium‐oxygen species in solutions with different concentration and pH had been well‐characterized firstly by the combination of SERS experiments with density functional theory (DFT) calculations. This work will promote the basic study of the V–O species, and it is also a promotion for the SERS and analytical chemistry.

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NO x is the main pollutant in the air, which causes many harmful effects on society. The V 2 O 5 /TiO 2 catalysts are very important to reduce the NO x from the heat engine plants and vehicle exhausts. However, various reasons will affect the performance of the catalysts. In this paper, the polymerization state of surface VO x of supported V 2 O 5 /TiO 2 catalysts was controlled by changing the pH value of the impregnation precursor solutions, and the redox and acidity properties of the catalysts can be adjusted consequently. The Raman spectroscopy, 51 V magicangle spinning nuclear magnetic resonance (MAS NMR), H 2temperature-programmed reduction (H 2-TPR), NH 3-temperature-programmed desorption (NH 3-TPD), NH 3-temperature-programmed oxidation (TPO) and 15 NH 3-NO-O 2-temperature-programmed surface reaction (TPSR) were mainly used for the characterization and properties tests of the samples. Although all catalysts in this work had similar surface morphology and the same vanadium loading, the catalyst oxidability decreased while acidity increased with the increasing of VO x polymerization, which causes the NO conversion increases with the increasing of VO x polymerization below 300°C in selective catalytic reduction (SCR) de-NO x reaction. This work will promote the advance in catalysis and anti-pollution fields for human and nature.