Photocatalytic primary alcohol oxidation on WO nanoplatelets

With the aid of direct heating through microwave irradiation in non-aqueous media, nanocrystalline tungsten( vi ) oxide is achievable in 30 minutes at 200 °C, faster and at a lower temperature than conventional synthesis methods. Forming in a platelet morphology, these particles are as small as 20 nm with a BET surface area of 37 m 2 g −1 WO 3 . These nanoplatelets are active for the photocatalytic oxidation of the 1° alcohols benzyl alcohol (rate constant, k of 2.6 × 10 −3 h −1 ) and 5-(hydroxymethyl)-2-furfural ( k of 0.01 h −1 ) using 10 mg of WO 3 with 2 mL of 0.250 M substrate in acetonitrile and a 150 mW cm −2 460 nm blue LED source. As expected, these rate constants are larger than those observed for commercially prepared, micron-sized WO 3 . XPS analysis shows that during catalysis, the concentration of W 5+ on the surface increases, but the nanoplatelets are stable under these reaction conditions. The overall morphology and size of the particles are retained through the reactions. Moreover, the nanoplatelets are recyclable-showing no loss in activity for four reaction cycles. With the aid of direct heating through microwave irradiation in non-aqueous media, nanocrystalline tungsten( vi ) oxide is achievable in 30 minutes at 200 °C, faster and at a lower temperature than conventional synthesis methods.