Research paperChemical-bond conjugated BiO(OH)xI1-x-AgI heterojunction with high visible light activity and stability in degradation of pollutants

•A layered BiO(OH)xI1-x solid solution was grown on the surface of AgI particles.•9-fold enhanced photoactivity was achieved for the BiO(OH)xI1-x-AgI heterojunction.•AgI photodecomposition was suppressed without any release of Ag+.•The interfacial Ag-I-Bi chemical bond junction accelerated carriers transfer.•The spatial separation of photoexcited electrons and holes was realized.

A layered BiO(OH)xI1-x solid solution was grown in situ on the surface of AgI particles by a one-pot co-crystallization method. Based on the results of XPS, EPR, XRD and other techniques, it was verified that a p-n heterojunction was formed through Ag-I-Bi cross-linking bonds in the interface of BiO(OH)xI1-x and AgI due to the common species of I− ions. The resulting BiO(OH)xI1-x-AgI exhibited high efficiency and stability for photodegradation of phenolic compounds with visible light irradiation. No significant AgI decomposition or release of Ag+ or Bi3+ was observed in the photoreaction, and the photoactivity of AgI was enhanced almost 9-fold. These enhanced photocatalytic properties were attributed to the strong interfacial interaction between BiO(OH)xI1-x and AgI by the Ag-I-Bi bond junction. Due to the chemical-bond junction, the photogenerated electrons in the CB of AgI quickly transferred to the CB of BiO(OH)xI1-x to produce O2－, while the holes in the VB of BiO(OH)xI1-x migrated to the VB of AgI to oxidize pollutants in water. The accelerated interfacial charge transfers were responsible for the high photostability and photoactivity of BiO(OH)xI1-x-AgI.

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