Facile synthesis of bulk Au-Co-CoOx-CeOx@iron ball and its photocatalytic application in 4-nitrophenol degradation

[Display omitted] •Au/Co-CC@iron ball shows superior photocatalytic activity, stability and reusability.•High property is due to synergy of active components and foliated iron ball surface.•Au/Co-CC@iron ball is used as packing material to construct packed reactor/module.•Via reactor/module, the removal of 4-NP is unprecedentedly enhanced to 2750 μmol/h.•Reactor/module has great potential in the continuous-flow degradation of 4-NP. Bulk noble metal–semiconductor composites can be chosen as photocatalysts to carry out the flow degradation of 4-nitrophenol (4-NP) whereas their preparation is complex and uncontrollable. Here, bulk Au-Co-CoOx-CeOx@iron ball (Au/Co-CC@iron ball) is designed and prepared by a facile and controllable route without any toxic chemical. The bulk Au/Co-CC@iron ball shows excellent photocatalytic activity and reusability for the 4-NP degradation, which can be ascribed to the synergistic action of active components and foliated iron ball surface. Furthermore, the highly active Au/Co-CC@iron ball is used as packing material to construct a new-type of packed reactor, by which the flow degradation of 4-NP is successfully achieved. As-fabricated packed reactor and its tandem module exhibit superior photocatalytic performance for the flow degradation of 4-NP. Noteworthy, based on the tandem module with six reactors, the removal rate of 4-NP can reach up to 2750 µmol/h. Meanwhile, the reactor and its module display satisfactory operational stability and reusability in the flow degradation of 4-NP. Clearly, the provided route is effective for the preparation of bulk noble metal–semiconductor composites with exceptional performance, which can also be a prospective strategy to obtain bulk packing materials to serve for the flow degradation.