Research paperAgBr-wrapped Ag chelated on nitrogen-doped reduced graphene oxide for water purification under visible light

•AgBr-wrapped Ag dispersedly anchored on N-doped RGO was fabricated.•AgBr@Ag-N-RGO was highly effective and stable for pollutants removal under visible light.•The good interfacial contact enhanced effective electron separation and transfer.•The electron transfer process was confirmed from Ag to AgBr and from pollutants to Ag by N-RGO.

A visible-light-driven photocatalyst AgBr@Ag/nitrogen-doped reduced graphene oxide (AgBr@Ag/N-RGO) was prepared by a hydrothermal-in situ oxidation method, and characterized by scanning and transmission electron microscope, X-ray diffraction, Fourier-transform infrared spectra, Raman and X-ray photoelectron spectroscopy. AgBr@Ag/N-RGO exhibited high photoactivity and photostability to degrade and mineralize various organic pollutants, as demonstrated with 2-chlorophenol, phenol, bisphenol A and diphenhydramine in water under visible light. Its photoactivity was 20, 5.3, and 2.9 times higher than that of Ag/N-RGO, TiO2-xNx, and AgBr@Ag, respectively for the photodegradation of 2-chlorophenol. The characterized results verified that Ag nanoparticles (NPs) was first chelated by N-groups of N-RGO and then enwrapped by AgBr by in-situ oxidation, which was contributed to the enhancement of interfacial electron transfer in AgBr@Ag/N-RGO. Furthermore, the two charge transfer processes were elucidated that the plasmon-induced electrons on Ag NPs core transferred to AgBr shell, and could be further transferred away together with the photoexcited electrons on AgBr by N-RGO to interact with O2 to form O2−, while the electrons of pollutants were accerelated to transfer to the plasmon-induced Ag NPs by the Ag-N complex along the π-π graphitic carbon network of N-RGO, which was responsible for the photoactivity and stability of AgBr@Ag/N-RGO.

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