Synthesis of redox-mediator-free direct Z-scheme AgI/WO3 nanocomposite photocatalysts for the degradation of tetracycline with enhanced photocatalytic activity

•Redox-mediator-free direct Z-scheme AgI/WO3 heterojunctions were prepared.•AgI/WO3 heterojunction have strong interfacial interaction.•The catalysts showed great photocatalytic efficiency on tetracycline degradation.•The enhanced activity was mainly due to the direct Z-scheme system.•The hole and superoxide radicals are the two main photoactive species.

Novel visible-light-driven AgI/WO3 nanocomposites were synthesized by a facile precipitation method. Multiple techniques were applied to investigate the structures, morphologies, optical and electronic properties and photocatalytic performance of as-prepared samples. The photocatalytic performance of the AgI/WO3 nanocomposites was evaluated sufficiently by using colorless antibiotic agent tetracycline hydrochloride (TC). The optimum photocatalytic performance of TC photodegradation over 20%-AgI/WO3 is as about 4.3 and 25 times high as that of pure AgI and WO3, respectively. The possible mechanism for the enhanced photocatalytic activity could be attributed to the formation of a redox-mediator-free direct Z-scheme system which causes the photogenerated electrons migrate from WO3 to AgI, leading to effective charge separation of WO3. Furthermore, the stability and the possible mechanism of AgI/WO3 nanocomposite photocatalysts for TC degradation are also elucidated.

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