Hydrothermal Preparation and Photocatalytic Water Splitting Properties of ZrW2O8

ZrW2O8 was prepared by adjusting Zr : W mole ratio and HCl concentration in hydrothermal reaction processes. The obtained sample was crystallized in alpha-ZrW2O8 phase (cubic, P2(1)3), with band gap energy of 4.0 eV. The properties of photocatalytic water splitting were examined under UV light irradiation. The average rate of H-2 evolution over 0.3wt% Pt/ZrW2O8 in the presence of CH3OH as electron donor (ED) was 23.4 mu mol/h, while the average rate of O-2 evolution over ZrW2O8 in the presence of AgNO3 as electron scavenger (ES) was 9.8 mu mol/h. Moreover, H-2 was evolved over 0.3wt% Pt/ZrW2O8 from pure water splitting at a rate of 5.2 mu mol/h. The study indicated that the band structure of ZrW2O8 was suitable for reducing H+ to H-2 and oxidizing H2O to O-2. The band structure and photocatalytic water splitting properties of ZrW2O8, different from either ZrO2 (5.0 eV) or WO3 (2.7 eV), were attributed to the hybridization of W5d and Zr4d in conduction band (CB) as well as the change in crystal structure.