Promoted visible-light-assisted oxidation of methanol over N-doped TiO2/WO3 nanostructures

Abstract Alcohol oxidation is an important chemical reaction with a great deal of interest in the fields of energy and industrial sectors. Herein, n-TiO2@WO3 heterojunction photocatalysts were fabricated and their catalytic activity toward the visible-light-assisted oxidation of methanol was studied. A series of n-TiO2@WO3 photocatalysts with different weight ratios of n-TiO2 as 1, 1.5, 2.3, and 4 wt % were prepared using a simple hydrothermal approach. The prepared materials were characterized using standard physiochemical techniques including TEM, SEM, XRD, EDX, XPS, physisorption (BET), FTIR, Raman, DRS, and PL spectroscopy. The promoting effect of the n-TiO2 on photocatalytic activity was studied by varying the ratio of n-TiO2 in the composite photocatalysts. The effect of illumination time on methanol photo-oxidation was investigated up to 3 h. The interplay of n-TiO2 and WO3 could extend the photosensitivity of TiO2 into the visible region of the solar spectrum and decrease the recombination of the photogenerated electron-hole pairs. The hybrid n-TiO2@WO3 photocatalyst demonstrated enhanced photocatalytic activity for methanol oxidation compared to pure counterparts. The 2.3 wt% n-TiO2/WO3 composite photocatalyst achieved the highest photocatalytic conversion of methanol to formaldehyde of 48.4 mmol L−1 upon visible-light illumination (150 mW/cm2) for 3 h. The present paper demonstrates a non-conventional, efficient, and green approach for the photooxidation of methanol. The utilization of solar energy for alcohol oxidation can have immense advantages energetically and economically.