Boron doped fluorescent carbon nano dots for the reduction of ionic dyes and as encryption/decryption QR security code labels

Abstract

This work discusses the synthesis of fluorescent undoped and boron-doped carbon nanodots (BDCNDs) by a simple hydrothermal approach using Tribulus terrestris as the carbon precursor and boric acid as the boron source. The morphology of BDCNDs was analyzed by HRTEM, which confirmed the spherical-shape and its size was found to be 3.6 nm. The XRD results reveal the amorphous nature and Raman spectroscopy was used to investigate the graphitic structure of BDCNDs. The obtained BDCNDs were exposed to blue fluorescence with a quantum yield (QY) of 19.2%. The synthesized green nano catalysts (BDCNDs) were used to reduce organic dyes, with NaBH₄ and the findings showed that they had a high catalytic activity against two cationic dyes (Congo red (CR) and Eosin Yellow (EY)), and two anionic dyes (Malachite Green (MG) and Methylene Blue (MB)). The Langmuir–Hinshelwood mechanism was used to assess the catalytic effect of BDCNDs on dyes. Further, we designed an anti-counterfeiting system for up-gradation of the security level by the stencil printing method. The fluorescent security label known as “confidential info” was encoded on a quick response (QR) system and a mobile is used to read the decoded information under 365 nm UV light irradiation.