Built-in electric field mediated S-scheme high-quality charge separation in BiVO4/NiAl-LDH heterojunction for highly efficient photocatalytic degradation of antibiotics

Abstract

As an up and coming technology for antibiotics removal from water, photocatalysis required well-pleasing charge isolation, migration, and utilization efficiency to come true an efficaciously photocatalytic performance, but developing affordable and high-efficiency photocatalyst remains a great challenging. Herein, an emerging S-scheme BiVO4/NiAl-LDH heterojunction was ingeniously fabricated by mulberry-like BiVO4 microrods immobilized onto the surfaces of flower-like NiAl-LDH microspheres. The physicochemical properties of the BiVO4/NiAl-LDH heterojunctions were analyzed by multiple techniques. Expectedly, the manufactured BiVO4/NiAl-LDH heterojunction endowed a significantly strengthened removal rate of tetracycline compared to mono-component BiVO4 and NiAl-LDH under visible light. Specifically, the optimized BVO-NAL-3 manifested the exceptional tetracycline removal efficiency with an apparent rate constant of up to 0.0409 min−1, which was close to 34.1 and 4.4 times more rapid than those of neat NiAl-LDH and BiVO4, severally. This signal enhancement was centrally related to the creation of S-scheme heterojunction, which accelerated high-quality charge separation and strengthened redox capacity under the force of created a built-in electric field, which was corroborated by experiments results together with density functional theory calculations. Besides, the generation of superoxide radicals and photogenerated holes played an imperative role in the tetracycline degradation over BVO-NAL-3. Noteworthily, BVO-NAL-3 expressed the satisfactory stability and exceptional resistance to environmental interferences. More amazingly, other refractory antibiotics including ciprofloxacin, levofloxacin and amoxicillin were also efficaciously eliminated by BVO-NAL-3. Ultimately, the possible degradation mechanism and pathways of tetracycline were logically inferred. This work unveils a valuable afflatus for the reasonable layout and establishment of S-scheme heterojunction with high-quality charge separation for the eradication of antibiotics.