Enhanced photooxidation and colorimetric sensing application of praseodymium oxide-modified boron-doped g-C3N4

Abstract

This paper presents a straightforward one-pot method for creating a novel composite sample consisting of graphitic carbon nitride (g-C₃N₄), boron, and praseodymium oxide (B-g-C₃N₄ (Pr x%)). This synthesis utilized urea, boric acid, and praseodymium nitrate, employing cost-effective and simple techniques. The peroxidase mimic performance of the resulting composites was successfully demonstrated. These materials are effective catalysts, aiding the reduction of H₂O₂, which in turn supports the oxidation of a well-known reagent named 3,3′,5,5′-tetramethylbenzidine (TMB), a colorless substance which shows peroxidase activity to form blue colored oxidized TMB (ox TMB) in the presence of H₂O₂. Thus, a simple colorimetric technique for sensing H₂O₂ is developed utilizing the synthesized material's enzyme mimic activity. The synthesized B-g-C₃N₄ (Pr x%) composites exhibited high selectivity and sensitivity towards H₂O₂ sensing with a detection limit of 0.236 μM in a linear detection range of about 0.05 μM to 10 μM. The B-g-C₃N₄ (Pr x%) composites also demonstrated excellent photocatalytic conversion of TMB to blue coloured ox TMB upon visible light illumination. The thus formed blue ox TMB solution demonstrated a characteristic colour change to green with a decrease in the intensity with a higher concentration of formalin. Hence, a colourimetric sensor was employed for the sensing of formalin with a detection limit of 0.18 μM in a linear range of about 0.05 μM to 70 μM concentration. In conclusion, the B-g-C₃N₄ (Pr x%) nanocomposite exhibits notable photooxidation and peroxidase mimetic activities, indicating its potential in environmental remediation and colorimetric sensing applications. This colorimetric approach presented in this study is very selective, rapidly responding, cost-effective, green and sensitive. It may be employed for the detection of H₂O₂ and formalin in adulterated food samples.