Carbon-modified Bi2WO6nanostructures with improved photocatalytic activity under visible light

Abstract

Carbon-modified Bi₂WO₆ (C–Bi₂WO₆) nanostructures were synthesized via a hydrothermal process in the presence of glucose followed by the calcination in Ar gas at 500 °C. The morphologies and crystallinity of Bi₂WO₆ and the nature of carbon in the composites obtained with different glucose amounts were characterized. Raman spectrum analysis, electron microscopy results and light absorption of C–Bi₂WO₆ at wavelengths larger than 450 nm clearly confirmed the carbon modification. Further results indicated that glucose did not affect the final crystalline structure or the band gap of Bi₂WO₆, but it had great influences on the photocatalytic activity of Bi₂WO₆ towards rhodamine-B (RhB) degradation. When the glucose amount was less than 0.04 g, the photoactivity was enhanced step by step with an increase in the glucose amount. The improved photocatalytic performance could be ascribed to the enhanced photogenerated electron-hole separation and more RhB adsorption associated with carbon. However, when the glucose amount was higher than 0.04 g, the photocatalytic property dramatically decreased due to the severe absorption of almost incident light by carbon, which hindered the accessibility of light to Bi₂WO₆. Our work provides an alternative way to improve the photoactivity of Bi₂WO₆ nanomaterials.