Hydrothermally devised visible light-activated NiFe2O4/Bi4O5I2 composite for aquaculture wastewater decontamination and plastic waste photoreforming applications

Abstract

Devising promising photocatalysts with excellent redox potential has become towering challenges for environmental mitigation and energy crisis. In this work, a new NiFe₂O₄/Bi₄O₅I₂ (NFO/BOI) composite photocatalyst has been fabricated using a simple two-step hydrothermal method. The structural, optical and electrochemical traits of the composite photocatalyst was systematically scrutinized by myriad kinds of analytical approaches. The devised composite photocatalyst was then employed in the decontamination of chlortetracycline hydrochloride (CTH) antibiotic and the photoreforming of polyethylene terephthalate (PET) plastic waste under visible light. As compared to individual materials, 5 wt% NFO/BOI demonstrated a remarkable photoactivity towards the CTH photodegradation of 93.3 % within 60 min visible light exposure. Interestingly, when CTH was added into the real aquaculture wastewater, the NFO/BOI composite photocatalyst can also retain its high CTH decomposition of 82.1 % and COD removal of 74.9 %. Such an enhancement in photoactivity performance was mainly because of effective light absorption, good charge separation and the composite photocatalyst also afforded a good recyclability after several cyclic runs. Moreover, the phytotoxicity assessments demonstrated that the treated aquaculture wastewater promoted the germination of water lettuce seeds. Besides, the NFO/BOI composite photocatalyst can achieve a hydrogen evolution rate of 27.8 μmol·gcat⁻¹·h⁻¹ from PET plastic waste photoreforming. A possible charge transfer mechanism over S-scheme NFO/BOI heterojunction was also divulged based on test outcomes. This study highlighted the potential of using a new composite material as an efficient and long-lasting way in cleaning the organic contaminants in aquatic environment.