Bi4TaO8Cl/Graphene nanocomposite for photocatalytic water splitting

Abstract

Sillen-Aurivillius structures like Bi4NbO8Cl, Bi4TaO8Cl, and Bi4TaO8Br have been expected as efficient visible light active photocatalysts thanks to their narrow band gaps less than 2.5 eV and suitable negative conduction band potential for hydrogen production reaction, 0.0 V vs NHE. However, despite their excellent potential the photocatalytic hydrogen generation efficiency of them under visible light has remained low. The low activity is usually attributed to the shallow defect levels near the conduction band, causing fast recombinations of photoexcited electrons and holes. In this study, a nanocomposite of Bi4TaO8Cl and graphene is proposed for overcoming this issue. The excellent electron conductivity and abundant delocalized electrons from the conjugated sp2-bonded carbon networks in graphene can facilitate the transfer of electrons from Bi4TaO8Cl conduction band and increase the photocatalytic efficiency. Bi4TaO8Cl/graphene nanocomposite was successfully prepared by a hydrothermal method, and photocatalytic activity enhanced both under UV and visible light.