Enhanced Photoluminescence of Potassium-doped Tungsten Oxide by Acetone Exposure

Tungsten trioxide is a common transition metal oxides that has been extensively studied due its potential applications in photoelectrochemistry, photocatalysis, gas sensing, etc. The optical and electronic properties of the material can be tuned by doping the structure with various elements and exposure to different gaseous environments. Studies of the optical properties of doped nanocrystals of tungsten trioxide in different gaseous environments can help elucidate new information about the material. Here, molecule-enhanced photoluminescence (PL) of potassium-doped tungsten oxide (K_xWO) was explored in the presence of different gases to understand charge transfer between molecules and K_xWO on the properties of the material. We performed Raman spectroscopy and PL experiments in the presence of gaseous acetone or ethanol mixed with other gases (N₂ and O₂). PL at 630 nm from KWO was observed and further enhanced when the sample was continuously irradiated with a 532 nm CW laser in an acetone/ N₂ mixture. The PL was also observed with similar behavior in the ethanol/N_2, and acetone/O₂ mixtures but the signal intensity was much lower. A mechanism of strong emission of the PL induced by the charge transfer between the acetone and the K_xWO is proposed.