Mo-doped BiVO₄ is used to solve the polarization problem caused by highly insulating solid discharge products in Na−O₂ batteries. The results show that it has strong light absorption ability and charge separation ability. With the light assistance, it produces large amounts of carrier, thus promoting the decomposition of discharge products and effectively improving the cycling life of the batteries.

Abstract

The highly insulated solid discharge products in sodium-oxygen (Na−O₂) batteries induce large polarization and thus heavily threaten their cycle life. Controlment of discharge products taking efficient catalyst is a best way to solve this problem. Here, Mo-doped BiVO₄ as the catalyst produces large amounts of carrier, thus boosting the battery reaction and reducing the overpotential under the light assistance. Compared with the BiVO₄ without Mo doping, the doped one has a lower recombination of photogenerated carriers, thus benefiting a large polarization suppression and Na−O₂ batteries running for over 270 cycles under 3.65 V as well as a fine rate performance. Besides, Mo doping reduces the size of BiVO₄, beneficial for the carrier transportation and more reactions due to the large specific surface area. Experiment combined with theoretical calculation shows that Mo doping is advantageous to enhancing catalytic activity of BiVO₄ due to a lower work function for easier electron extraction, thus enhancing Na₂O₂ decomposition capability. This work undoubtedly inspires photocatalysts′ use for solving the insulated solid discharge products decomposition in metal-O₂ batteries and provides a guide for other photocatalysts possibilities.