Discovery of new surface-enhanced Raman spectroscopy (SERS) substrates consisting of inexpensive and earth-abundant elements is an unmet need for the advancement of future analysis techniques for the ultrasensitive detection and quantification of chemical and biological analytes. Nanostructures (NSs) of noble metals such as Au, Ag, and Cu are the benchmarks for the preparation of highly efficient SERS substrates because of their unique localized surface plasmon resonance (LSPR) properties. Non-noble-metal SERS substrates, e.g., metal chalcogenide semiconductors and transition metal oxides, have been prepared to mitigate the cost
however, their low sensitivity restricts widespread applications. In this article, we report for the first time that the structure of oxygen-deficient, LSPR-active, nonstoichiometric tungsten oxide (i.e., WO