Enhanced photocatalytic degradation of methylene blue using bimetallic C,N-doped NiO/ZnO derived from metal-organic frameworks

Organic waste pollution is a severe environmental and human health issue that urgently needs to be addressed. Photocatalysis has emerged as an effective method for removing contaminants from organic wastes. Porous metal oxides derived from metal-organic frameworks (MOFs) have been widely developed and applied in organic waste degradation processes. This study successfully synthesized p-n heterojunction NiO–ZnO doped with carbon and nitrogen using Ni-ZIF-8 as a template through a two-step calcination process. The inert atmosphere preserved the carbon and nitrogen contents of Ni-ZIF-8, resulting in carbon- and nitrogen-doped NiO–ZnO. The presence of the p-n heterojunction system and carbon and nitrogen doping was confirmed by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and optical characterization. Carbon and nitrogen-doped NiO–ZnO exhibit broad light absorption, low recombination rates, and low charge resistance, which are beneficial for methylene blue (MB) degradation. Specifically, C, N–NiO(20)-ZnO demonstrated the best MB degradation performance, achieving ∼100 % degradation within 150 min and maintaining a high stability over four cycles. Scavenger tests indicated that •OH played a crucial role in MB degradation. This research provides new insights into the synergistic effect of the p-n heterojunction system and carbon and nitrogen doping to enhance the degradation performance of organic waste.