Study on mechanism of hydrogen adsorption on WO 3 , W 20 O 58 , and W 18 O 49

The density functional theory (DFT) calculation of hydrogen adsorption on tungsten oxides and calculation of the crystal structure of WO 3 , W 20 O 58 , and W 18 O 49 were performed . These calculations suggest that the length of W‐O bonds in WO 3 are 1.913 Å, the length of 66% W‐O bonds in W 20 O 58 is 1.8 to 1.9 Å, and the length of 43.48% W‐O bonds in W 18 O 49 is longer than 2.0 Å. The hydrate (WO 2 [OH] 2 ), as an autocatalyst in the hydrogen reduction process, was found in the particular adsorption configuration of W 18 O 49 . The WO 3 and W 20 O 58 were completely reduced within 40 to 60 minutes at a temperature of 1000°C and at a hydrogen flow rate of 200 mL/min, while W 18 O 49 was completely reduced within 20 to 40 minutes. The phase composition and micromorphology of raw material and production were studied by both X‐ray diffraction analysis (XRD) and FE‐SEM technology. The differences of the mechanism of hydrogen adsorption on WO 3 , W 20 O 58 , and W 18 O 49 were explored based on the density functional theory calculation and the hydrogen reduction experiments.