A three-dimensional TiO2/C/BiOBr graphene aerogel for enhancing photocatalysis and bidirectional sulfur conversion reactions in lithium-sulfur batteries

In order to prepare convenient recycled photocatalysts and improve their photocatalytic degradation efficiency, TiO2/C/BiOBr graphene aerogel (TCBA) with excellent photocatalytic activity and recyclability is successfully prepared by a combination of electrostatic spinning with solvothermal method. The introduction of graphene aerogel not only increases the specific surface area to obtain more active sites, but also enhances the conductivity of the material and accelerates electron transfer. Under simulated sunlight irradiation, the optimal ratio of TCBA composites (2TCBA-Ⅱ) has a high degradation rate for cationic dyes, anionic dyes, and antibiotics by the synergistic effect of physisorption and photocatalysis. Radical trapping experiments indicate that·OH plays a major role in the photocatalytic degradation of organic pollutants, and we propose an indirect Z-scheme heterojunction photocatalytic system. In addition, the 2TCBA-Ⅱ composite is applied to modify the lithium-sulfur (Li-S) battery separator, and the maximum discharge specific capacities are 1271 and 854 mAh g−1 at current densities of 0.2 C and 0.5 C, respectively. After 300 cycles, the discharge specific capacity can be maintained at 530 and 357 mAh g−1, respectively, and the Li-S battery assembled by the 2TCBA-Ⅱ modified separator also has good rate performance. It indicates that the conveniently recycled three-dimensional (3D) composite 2TCBA-Ⅱ can better adsorb polysulfides, and provides multi-dimensional electron transport pathways with accelerated electrochemical reaction rates, thus enhancing the bidirectional conversion reaction of sulfur. Thus, the TCBA composites have important application prospects in both photocatalysis and Li-S batteries.