Floated Bi4Ti3O12@MoS2 p-n heterojunction anti-fouling hydrogels for efficient seawater purification

Photocatalytic treatment of seawater pollutants has far-reaching significance for marine conservation, but the recyclability in marine environments and their unavoidable threat from biofouling constrain their practical applications. Herein, a floated Bi₄Ti₃O₁₂@MoS₂ p-n heterojunction anti-fouling hydrogel (BMH) is fabricated through two-step hydrothermal method, where Bi₄Ti₃O₁₂ nanoparticles (E_g=3.1 eV) and flower-like MoS₂ (E_g=1.76 eV) form p-n heterojunctions with a 2D-2D structure and package to a three-dimensional driver-responsive hydrogel consisting of poly (vinyl alcohol) (type 1799), tannic acid and N-isopropylacrylamide for marine environmental protection. Under light irradiation, the formation of a p-n heterojunction in BMH facilitates the generation of primary active species, namely ·OH and ·O₂^-, thereby endowing the system with enhanced redox capability. Among them, 30 wt% BMH achieved the best removal efficiency of 98.2 % of 10 mg/L TC, which is 1.38 times that of pure nanoparticles Bi₄Ti₃O₁₂@MoS₂ 23.17 times that of the blank hydrogel. Simultaneously, the optimal bacterial attachment rate and anti-diatom attachment rate reach 99.3 % and 93.82 %, respectively, confirming the excellent antifouling properties of BMH. The degradation intermediates exhibit environmental friendliness, providing potential for further practical applications in seawater purification.