Enhanced photocatalytic performance of C3N4 via doping with π-deficient conjugated pyridine ring and BiOCl composite heterogeneous materials

In this paper, a novel heterojunction material was synthesized of C3N4 via doping with π-deficient conjugated pyridine ring molecules (2,6-diaminopyridine) and BiOCl by ultrasound-assisted method. First, doping C3N4 with 2,6-diaminopyridine can reduce the structural integrity and orderliness of C3N4, and reduce the number of structural fragments, Which makes C3N4 have more reactive sites. And then BiOCl nanosheets were grown on the surface of the modified C3N4 nanosheets to obtain a new heterojunction material composed of modified C3N4 doped with π-deficient pyridine ring molecules and BiOCl by the co-precipitation method. At last, the degradation of methyl orange (MO) by BiOCl, C3N4, modified C3N4 doped with 2,6-diaminopyridine, and a series of C3N4 doped with 2,6-diaminopyridine and BiOCl composite heterojunction materials under visible light was studied. X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), ultraviolet visible diffuse reflection (UV–Vis DRS) and transient photocurrent densities, and electrochemical impedance spectroscopy (EIS) were used to analyze the structure, morphology, and photogenerated charge transfer characteristics of samples. The experimental results show that the new heterojunction composite materials has better photocatalytic activity compared with pure BiOCl, C3N4, and modified C3N4 doped with 2,6-diaminopyridine. In addition, the degradation performance of methyl orange with different mass ratios of composite materials is also different. When the mass ratio of C3N4 doped with 2,6-diaminopyridine to BiOCl is 1:2, The composite material exhibits the best photocatalytic performance, which may be related to the synergistic effect of the modified C3N4 doped with 2,6-diaminopyridine and BiOCl. Based on the band structure and active species experiments, the reasons for the enhanced photocatalytic activity are discussed, and the possible degradation mechanisms are proposed. The research in this paper provides an effective new way to construct new heterojunction materials.