The BET surface areas were determined by N 2 adsorption-desorption isotherm measurements at 77 K (Autosorb-iQ, USA), and low-pressure CO 2 adsorption isotherms were conducted at 273 K for both WO 3 and WO 3 -001. The pore-size analysis of the prepared sample was based on a nonlocal density functional theory (NLDFT) model.