Insight into the influence of noble metal decorated on BiFeO3 for 2,4-dichlorophenol and real herbicide wastewater treatment under visible light

[Display omitted] •Influences of NM (Au, Ag and Pt) cocatalysts decorated on BiFeO3 were prepared.•NM boosted light harvesting capability and effectively suppressed charge carrier.•Pt-BiFeO3 showed highest 2,4-DCP degradation efficiency among composites.•Pt-BiFeO3 can be recycled with a minimal Pt leakage over seven cyclic runs.•Photocatalytic mechanism, degradation pathway and toxicity test were also studied. The exploitation of effective and environmental benign techniques for treating agricultural runoff recalcitrant herbicides is an on-going challenge. In this regard, any feasible photocatalytic technology in the visible light region so as to adopt the abundant and clean sunlight serves as an indispensable task. Herein, different noble metal cocatalysts (NM = Au, Ag and Pt) decorated on BiFeO3 (NM-BiFeO3) composites were synthesized using a facile two-steps hydrothermal process, and characterized by physicochemical approaches to identify their structural, photoelectrochemical and optical traits. The Pt-BiFeO3 composites displayed prodigious visible light photodegradation of 2,4-dichlorophenol (2,4-DCP) (100 %), much higher than those Au-BiFeO3 (92.4 %), Ag-BiFeO3 (83.2 %), commercial TiO2 (67.5 %) and pristine BiFeO3 (64.1 %) in 240 min. The Pt cocatalyst was more effective than other NMs owing to its higher work function and height of Schottky barrier, which can be greatly delayed the recombination of charge carriers. Photoluminescence and photoelectrochemical measurements have also been taken to validate this conclusion. Based on these, the possible mechanism for photodegradation of 2,4-DCP over NM-BiFeO3 was postulated. The Pt-BiFeO3 can be recyclable for photodegradation of 2,4-DCP along with a minimal Pto ions leakage even after seven consecutive runs. The degraded intermediates of 2,4-DCP were also detected to propose degradation pathways. Moreover, according to the radical-capturing and terephthalic acid-photoluminescence tests, the core stimulus in the photocatalytic reaction were determined. The Pt-BiFeO3 had demonstrated its excellent catalytic ability in the real herbicide wastewater treatment. Toxicity assay of treated herbicide wastewater also showed minimal effects on the growth of wild algae.