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 .