Green synthesized carbon quantum dot as dual sensor for Fe(II) ions and rational design of catalyst for visible light mediated abatement of pollutants

Abstract

Herein we report the fabrication of carbon quantum dots through a green, cost-effective, and one-pot method from Wrightia tinctoria leaves. The CQDs are effective as fluorescent and electrochemical sensors for Fe(II) ions, with a detection limit of 2.3 nM. In the presence of Fe(II), strongly fluorescent quenching of CQDs occurred, providing the basis of Fe(II) quantification. The versatile sensing ability of CQDs in various real samples indicates the significant potential of carbon-based materials in developing sensing platforms for accurate and fast assay of different analytes. The synthesized green carbon dots and Bi4O5Br2 were fabricated on ZrO2 nanoparticles using a simple approach to create a high-efficiency ZrO2/CQD/Bi4O5Br2 photocatalyst composite to degrade contaminants. The fabricated CQD-based nanocomposite successfully degraded rhodamine B. The catalyst composition was optimized by varying Bi4O5Br2 content, and the ZrO2/CQD/Bi4O5Br2 (15 %) showed enhanced degradation efficiency and followed pseudo-first-order kinetics. More than 95 % of degradation efficiency in a short period and enhanced stability promise the nanocomposite's future industrial applications. This offers a novel approach to developing green carbon dots as a sensor for metal ions and its modified composites as visible-light-induced photocatalysts for the effective degradation of contaminants.