Photocurrent amplification of graphene intercalation with titanium dioxide in photoelectrochemical devices

•Graphene shows more than 10 times photocurrent amplification between TiO2 nanocrystalline film and metallic substrate.•The photoelectrochemical (PEC) device is developed by layer-by-layer self-assembled method with commercialized materials.•The ultraviolet light sensitivity of the PEC device is enhanced more than 10 times by the graphene intercalation layer.