Photocatalytic activity of electron-deficient and porous WO₃ nanoparticles derived from thermal oxidation of bulk WC particles

Electron-deficient and porous WO₃ particles were prepared by the simple thermal oxidation of commercial bulk WC. The crystal structure of as-prepared WO₃ particles was monoclinic phases and its crystallinity and morphology were controlled by varying the calcination temperature. Small and interconnected WO₃ particles were divided and formed from bulk WC particles with increasing calcination temperature. The electronic structure of thermally oxidized particles was studied by W L_III-edge XANES. Interestingly, as-prepared WO₃ samples were in an electron-deficient state (W^+6−δ). The photocatalytic performance of as-prepared samples was investigated in terms of oxygen production in AgNO₃ aqueous solution and decomposition of the organic dye, Rhodamine B. The photoelectrochemical and photocatalytic activity were correlated and the results were most favorable for WO₃ particles thermally oxidized at 700 °C for oxygen production and 600 °C for photocurrent production.