Data security has become an important issue in economic and military fields as well as in our daily lives.Stimuli-responsive photoluminescent materials can change their optical outputs of spectra and lifetime in response to external stimuli and possess extra security features that are difficult to mimic and duplicate.Therefore,stimuli-responsive photoluminescent materials have been widely used as security inks for applications in the fields of optical data recording,data storage and data security.[1] However,traditional fluorescent inks are usually visible by naked eyes either under ambient light or under the illumination of UV light,which is limited in maintaining the secrecy of information.Graphitic carbon nitride(g-C3N4)is the most stable allotrope of binary carbon nitride phases and has recently attracted great interest because of its semiconductor properties.