N-doped carbon dot from cigarette-tobacco: Picric acid sensing in real water sample and synthesis of CD-MWCNT nano-composite for UV-photodetection

Abstract

Carbon dots (CDs) are one of the most valuable nanomaterials in the recent world because of their diversity in applications. This work reports the applications of N-doped CDs in photoluminescence (PL) based picric acid (PA) sensing and the synthesis of CD- multi-walled carbon nanotubes (MWCNT) nano-composite for UV-photodetection. The CDs were synthesized from cigarette-tobacco by a single-step microwave-assisted heating technique. The detailed characterizations of the synthesized CDs have been performed as well. These synthesized CDs showed an average particle size of 2.8 ± 1.04 nm with a quantum yield (QY) up to ~9.98%. The calculated detection limit (LOD) for PA-sensing was 32.1 ppb, which is relatively low compared to the reported literature considering a wider linear range of concentration (0.1–50 μM). The sensing mechanism is also discussed in detail. This sensing ability was then successfully tested to detect PA acid in real water samples, which showed a good recovery percentage with a minimal deviation of ± 10%. For the second application, the CDs were attached with (MWCNTs) to synthesize a novel UV- photoresponsive CD-MWCNT nano-composite. The photocurrent-generation and the mechanism of electron transfer through the nano-composite have been discussed with detailed explanations. The transient photo-response of the nano-composite has also been presented. This transient response was used to calculate the rise and decay time of the system, and the observed values are of 0.38 and 0.42 s, respectively. Therefore, the ability of the CDs to be used in different areas of applications has opened up a vast range of scopes for the researchers.