Photocatalysts can be effectively recovered and reused by compounding with magnetic nanostructures. How to further improve the photocatalytic performance of magnetic heterojunction photocatalysts remains a great challenge. In this work, g-C 3 N 4 /ZnFe 2 O 4 (CN/ZFO) magnetic heterojunction photocatalyst was first prepared and then modified with ultrathin MoS 2 (CN/ZFO/MoS 2 ) by simple ball-milling method. Then the photocatalytic removal of Cr(Ⅵ) performance of the prepared series photocatalysts was evaluated in detail. The optimum CN/ZFO/MoS 2 can achieve 99.3% Cr(Ⅵ) removal under 200-min simulated sunlight illumination, which is much higher than CN/ZFO (54.0%). The enhanced photocatalytic performance benefits from the modification of MoS 2 , which improves the light absorption performance, facilitates the transfer of photogenerated carriers , increases the concentration of photogenerated carriers and promotes the effective separation of photogenerated carriers. This work provides a theoretical basis for further preparation of magnetic recyclable photocatalysts with high photocatalytic performance.
An energy-efficient and environmentally friendly nitrogen fixation process is urgently needed to solve problems of high energy consumption and high emissions in the traditional ammonia industry. In this work, a Z-scheme porous g-C 3 N 4 /ZnFe 2 O 4 photocatalyst was synthesized, characterized and employed for N 2 photofixation. Temperature programmed desorption characterization confirmed that the adsorption capacity of nitrogen was improved for the porous structure. From N 2 photofixation evaluation experiments, the highest ammonia production efficiency can reach 147.33 μmol/L within 120 min. Photocatalytic performance is greatly improved because of the increasing of specific surface areas, enhancement of N 2 adsorption ability and synergistic effect of Z-scheme photocatalytic system. In the ammonia production process of the research, visible light is used as energy; N 2 and H 2 O are used as raw materials, which possesses a good application potential due to the advantages of being energy-efficient, environmentally friendly and pollution-free.
Dual Z-scheme heterojunction with highly separation efficiency of photoinduced carriers and outstanding redox capability has received considerable attention and hold great promise for environmental remediation. Herein, magnetic dual Z-scheme g-C 3 N 4 /ZnFe 2 O 4 /Ag 2 CO 3 heterojunction was successfully constructed, and applied as a dual-function photocatalyst for tetracycline (TC) degradation and bacterial inactivation. The optimized g-C 3 N 4 /ZnFe 2 O 4 /Ag 2 CO 3 heterojunction exhibited excellent photocatalytic capacity for TC degradation with a rate constant of 0.0154 min −1 , which is 2.73, 3.08, and 2.92 times higher compared to that of the g-C 3 N 4 , ZnFe 2 O 4 , and g-C 3 N 4 /ZnFe 2 O 4 , respectively. Impressively, the g-C 3 N 4 /ZnFe 2 O 4 /Ag 2 CO 3 -1.25 heterojunction displayed satisfying activity within a wider range of pH (3.0–9.0), TC concentration (5–25 mg L −1 ), and with the addition of various anions including Cl - , HCO 3 - , SO 4 2- , and NO 3 - . Meanwhile, 6.5-log of Escherichia coli cells could also be inactivated by g-C 3 N 4 /ZnFe 2 O 4 /Ag 2 CO 3 -1.25 heterojunction under visible light. Mechanism exploration based on trapping experiment, electron paramagnetic resonance (EPR) analysis, and liquid chromatography-mass spectrometer (LC-MS) indicated that the improved photocatalytic performance resulted from the synergetic effect of semiconductors and constructed dual Z-scheme heterojunction, which significantly promotes charge separation rate and endows strong redox capacity. As expected, the toxicity of TC degradation intermediates was reduced according to the Toxicity estimation analysis based on a quantitative structure activity relationships (QSAR) method. Further, the g-C 3 N 4 /ZnFe 2 O 4 /Ag 2 CO 3 heterojunction also demonstrated magnetic separation property and satisfactory photocatalytic stability even after 4 cycles. This work offers a new perspective on constructing novel magnetic dual Z-scheme heterojunction with dual-function photocatalytic properties and is of significance for water remediation.
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