Figure 1. XRD pattern and FTIR spectra of BCN and HCCN. In summary, we have developed a novel high-security photochromic PUF tag based on HCCN nanosheets.

2025/05/0706:37:34 science 1947

Introduction to the results

Tags based on physical non-cloneable function (PUF) have been proven to be some of the most effective anti-counterfeiting strategies. However, developing low-priced, simple-to-manufacturing, easy-to-certify PUF-based anti-counterfeiting labels is still challenging. This article, Associate Professor Chen Xin and Professor Zheng Yuanhui's team published a paper titled "Carbon Nitride Nanosheet-Based Photochromic Physical Unclonable Functions for Anticounterfeiting Applications" in the journal of the "ACS Appl. Nano Mater.", and studied the preparation of photochromic PUF tag by randomly dispersing highly crystalline carbon nitride (HCCN) particles in polyvinyl acetate (PVAc). The color of the photochromic-derived PVAc/HCCN film was used as the first layer of safety, which was verified by the naked eye. The pattern of randomly distributed HCCN particles within the photochromic region (i.e., PUF) is used as the second layer of safety. PUF can be read through any smartphone equipped with a portable objective lens and then automatically verified by computer vision technology.

Graphics and text introduction

Figure 1. (a) XRD pattern and (b) FTIR spectrum of BCN and HCCN. (c) XPS results for investigation and fine scans of (d) C 1s, (e) N1s, and (f) K2p of (c) and HCCN.

Figure 2. Photochromic mechanism and design diagram of nanosheet CN film

Figure 3, (a) Color switching of HCCN base film. From left to right, films with three different mass ratios between PVAc and HCCN represent three photochromic states and their appearance in three different colors. (b) Absorption changes of the film during the first 20 cycles of color conversion. (c) Absorption spectrum of HCCN-Y, HCCN-G and HCCN-B films after ultraviolet irradiation at room temperature.

Figure 4. (a) Unbiased current test after UV irradiation stops. (b) Unpaired electrons and (c) DMPO- • O 2 - and (d) DMPO- • O • OH substances recorded in the dark environment of EPR.

Figure 5. Anti-counterfeiting tag decoding mechanism based on computer vision technology

summary

In short, we have developed a new photochromic PUF tag based on HCCN nanosheets with high security. This photochromic phenomenon is used as the first layer of safety protection and is easily verified by the naked eye. The random distribution of HCCN particles in PVAc films provides a second layer of security and can be authenticated by mobile phones using computer vision technology . The photochromic PUF tags based on HCCN nanosheets presented in this work provide a new optical anti-counterfeiting method, opening up a new application of CN materials .

Literature:

https://doi.org/10.1021/acsanm.2c03055

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