G-C₃N₄ tubes decorated with MnMoO₄·H₂O: Outstanding S-scheme photocatalyst for detoxification of water pollutants upon visible light

Recently, the utilization of heterogeneous photocatalysts has been proposed as an effective solution for environmental purification, as one of the solar energy conversion processes, under mild conditions. In this research, MnMoO₄·H₂O nanoparticles were anchored on tubular g-C₃N₄ (abbreviated as TGCN) by a one-pot hydrothermal route. The phase structure, electronic environment, spectroscopic characteristics, composition, morphology, surface area, and electrochemical properties of the resultant materials were explored using XRD, XPS, EDX, FESEM, HRTEM, FTIR, PL, photocurrent, EIS, and BET analyses. The photocatalytic activity of TGCN/MnMoO₄·H₂O (20 %) nanocomposite was 4.25, 5.36, 9.07, 12.4, and 8.84 times better than modified GCN, and 3.91, 2.77, 6.24, 10.9, and 6.82 times higher than MnMoO₄·H₂O in removals of tetracycline, rhodamine B, methylene blue, methyl orange, and fuchsine pollutants, respectively. The improved visible-light absorption and rapid charge migration/separation between TGCN and MnMoO₄·H₂O counterparts through S-scheme heterojunction route were the key reasons for the boosted photocatalytic performance. The biocompatibility of solution after decomposition of tetracycline via the growth of wheat seeds was verified. Finally, the stability of the binary TGCN/MnMoO₄·H₂O (20 %) heterostructure was measured by the stability test after four reuses.