Oxygen vacancy engineering of novel ultrathin Bi12O17Br2 nanosheets for boosting photocatalytic N2 reduction

The conversion of N2 to NH3 is one of the most promising processes in maintaining natural life and chemical production. Photocatalytic nitrogen reduction reaction (NRR) has the advantage of clean and sustainable, which is considered to be an ideal synthesis technology. In this work, we report the successful synthesis of Bi12O17Br2 ultrathin nanosheets through simple alkali treatment and solvothermal method. The Bi12O17Br2 ultrathin nanosheets can improve the separation of carriers and the transfer of photogenerated electrons to N2 molecules, thus improving the photocatalytic efficiency. Of note, the higher Bi/Br atomic ratio in Bi12O17Br2 is beneficial to broaden the light absorption edge, and the high concentration of O atoms is easy to produce oxygen vacancies on the surface during the synthesis process of Bi12O17Br2. The abundant oxygen vacancies and high specific surface area enable N2 molecules and water to have powerful chemical adsorption and activation. In addition, the photocatalytic reduction of N2 to NH3 in pure water shows excellent and stable performance, and the average generation rate of NH3 reaches up to 620.5 μmol·L-1·h-1. This study discovers that rich oxygen vacancies and ultrathin morphology may have a significant part in the process of the photocatalytic nitrogen reduction reaction.