Photocatalytic degradation of methylene blue through carbon dot-doped and amino-functionalized ZIF-8

Abstract

This paper uses a one-step synthesis method to prepare NH₂-ZIF-8/NCDs porous materials. A series of composite photocatalysts were obtained by adjusting the additional amount of nitrogen-doped carbon quantum dots (NCDs). The structural characteristics of the nanocomposites were characterized using XRD, FTIR, FESEM, TEM, and BET. The photocatalytic activity of NH₂-ZIF-8/NCDs nanocomposites was investigated through the photocatalytic degradation of methylene blue (MB). The results show that when the addition amount of ethylenediamine and NCDs is 1:5, the prepared NH2-ZIF-8/NCDs catalyst can degrade 76.2% of the 20 mg/L methylene blue (MB) solution within 5 minutes of illumination. 97.1% of MB was degraded after 60 minutes. The photocatalytic activity of NH₂-ZIF-8/NCDs photocatalyst is higher than that of ZIF-8 and ZIF-8/NCDs photocatalyst. Free radical capture experiments showed that hydroxyl radicals (·OH) were the main active species responsible for removing MB under light illumination.

Highlights

ü NH₂-ZIF-8/NCDs prepared by the one-step synthesis method.

ü Adding ethylenediamine for amine modification changed the structure of ZIF-8 to a porous structure and increased the reaction sites of the catalyst.

ü Adding NCDs can achieve good charge separation efficiency.

ü NH₂-ZIF-8/NCDs catalyst exhibits excellent photocatalytic performance.