A novel hollow-hierarchical structured Bi2WO6 with enhanced photocatalytic activity for CO2 photoreduction.

Converting CO2 into high-valued chemicals with sunlight is regarded as a promising way to solve the impending energy and environmental crisis. Development of efficient photocatalysts with suitable energy band gap, high stability and favorable structure is thus of very importance. Herein, a novel hierarchical Bi2WO6 photocatalyst assembled by Bi2WO6 nanosheets with a hollow and rod-shaped appearance has been developed via a facile hydrothermal process. Interestingly, we found that the hydrolysis of Bi(NO3)3 in water can produce solid Bi6O5(OH)3(NO3)5·3H2O microrods which can be transformed to hollow-hierarchical Bi2WO6 nanosheets by virtue of the Kirkendall effect. The developed Bi2WO6 nanosheets exhibit a 58 times higher specific surface area than that of bulk Bi2WO6 and a remarkable enhancement in electrochemical performance such as photocurrent and charge transfer. As a result, the hollow-hierarchical structured Bi2WO6 photocatalysts achieve a high CH4 yield of 2.6 μmol g-1 h-1, 8 times higher than that of bulk Bi2WO6. Moreover, the developed photocatalysts exhibit a high stability during the recycling experiments. This work may present a new strategy to attain hierarchical structured photocatalysts with high activity and stability toward CO2 reduction.