The design and preparation of Mg and Zn co-doped carbon nitride with enhancing photocatalytic degradation efficiency for methylene blue

Carbon nitride (g-C3N4) is a potential material that can be used for the treatment of the wastewater contains organic dyes. However, the photocatalytic efficiency of g-C3N4 is limited by the wide band gap and fast recombination of photon-generated carriers. In this work, the co-doped with Mg and Zn of MgZn0.07-g-C3N4 was designed and prepared to enhance the photocatalytic efficiency. The co-doped Mg and Zn shorted the band gap of g-C3N4 from 2.74 eV to 2.50 eV. Interestingly, according to the DFT calculation, a Zn-bridge is formed between the interlayers of g-C3N4. The Zn-bridge reduces the electron localization and prolongs the existence time of photon-generated carriers. The as-prepared MgZn0.07-g-C3N4 was applied for the photodegradation of methylene blue. The degradation ratios and photodynamic parameter of MgZn0.07-g-C3N4 are higher than that of g-C3N4 and Mg-g-C3N4 (29.51 × 10−3 min vs 8.00 × 10−3 min).