Carbon Dots‐Decorated g‐C₃N₄ as Peroxidase Nanozyme for Colorimetric Detection of Cr(VI) in Aqueous Medium

Abstract

Carbon dots (CD) generated from biomass were fabricated on g-C 3 N 4 to construct a metal-free nanozyme with inherent peroxidase mimic functions. The formation of CD/g-C 3 N 4 was confirmed by different characterization techniques. The CD/g-C 3 N 4 displays distinct peroxidase mimic activities, as evidenced by the catalyzed oxidation of TMB (3,3',5,5', -tetramethylbenzidine) in the presence of H 2 O 2 , as well as color alteration from transparent to blue. The mechanistic analysis of peroxidase activity indicated that H 2 O 2 was catalyzed by CD/g-C 3 N 4 to produce reactive oxygen species. In an acidic solution, the presence of Cr (VI) accelerates the breakdown of H 2 O 2 to * OH radicals thereby increasing the rate of TMB oxidation. Hence, a visual colorimetric sensor was developed for the purpose of detecting Cr(VI) with limits of detection (LOD) 0.31 μM, based on the accelerated electron transfer between TMB and H 2 O 2 with the assistance of CD/g-C 3 N 4 .

Boosting the photodegradation of rhodamine B with the CuWO4/g-C3N4 heterojunction by introducing biomass derived N-CQDs as an electron mediator: mechanism and DFT calculations

“…g-C 3 N 4 was produced via thermal polymerization of urea. 43 A conventional procedure involved placing 20 g of urea in a silica crucible with a covered lid placed in a muffle furnace and calcining it for two hours at 550 °C at a heating rate of 50 °C min −1 . After cooling, yellow-colored bulk g-C 3 N 4 was generated.…”

Nanozymes: powerful catalytic materials for environmental pollutant detection and degradation

“…Second, introduction of Cr 6+ can affect the kinetics of nanozyme-catalyzed reactions, 35,[37][38][39] providing a strategy to achieve the sensing of toxic Cr 6+ . For instance, Amini and coworkers found that hexacyanoferrate-inserted Ni/Al layered double hydroxides (Ni/Al-Fe(CN) 6 LDH) exhibited certain peroxidase-like activity in triggering the oxidation of nonfluorescent terephthalic acid (TA) to TAOH with a fluorescence emission in the presence of H 2 O 2 .…”