Abstract
This study tests the theory of using a p-n junction to inhibit the recombination of photo-generated electrons and holes in N–MgO/g-C3N4 for the photocatalytic degradation of methylene blue (MB) dye. While the use of n-type semiconductor junctions with g-C3N4 for bandgap narrowing is well-studied in dye degradation, this research explores the innovative application of nitrogen (N)-doped MgO to create a p-type junction with n-type g-C3N4. The N–MgO/g-C3N4 nanocomposites were designed and synthesized to leverage both the bandgap narrowing effect and the formation of a p-n junction. The results demonstrate that these nanocomposites can effectively degrade MB dye under sunlight, achieving over 90 % degradation efficiency with a bandgap of 2.63 eV. Under high pH conditions, the degradation efficiency further increased to 94 %. The enhanced photocatalytic activity of the N–MgO/g-C3N4 composite is attributed to the formation of a heterojunction, which facilitates efficient separation and transmission of photo-induced charge carriers. This study discusses the detailed mechanism of this enhanced activity, emphasizing the role of the p-n junction in promoting effective charge separation and transfer, thereby improving the photocatalytic performance under sunlight.
•N–MgO/g-C3N4 nanocomposites form a p-n junction, enhancing separation of photo-generated charge carriers, thus improving photocatalytic performance.•The N–MgO/g-C3N4 composite achieved over 90 % methylene blue (MB) dye degradation under sunlight, further increasing to nearly 94 % under higher pH conditions.•The bandgap reduced to 2.63 eV in N–MgO/g-C3N4 composite, enhancing light absorption and boosting MB dye degradation.•The study details the role of the p-n junction in efficient charge separation and transfer, for improved photocatalytic activity under sunlight.