A mild synthetic route to Fe3O4@TiO2-Au composites: preparation, characterization and photocatalytic activity

•Anatase TiO2 NPs were uniformly deposited on monodisperse Fe3O4 to form core–shell Fe3O4@TiO2 by non-thermal process.•The main feature is direct deposition of anatase TiO2 NPs under mild condition, thus avoiding any high temperature treatment.•Evenly distributed Au NPs on TiO2 significantly increased its photocatalytic activity.•Superparamagnetic Fe3O4 cores could greatly facilitate the separation of the photocatalyst from the treated water.