Microwave-assisted fabrication of g-C3N4 nanosheets sustained Bi2S3 heterojunction composites for the catalytic reduction of 4-nitrophenol

In this work, we report a stable g-C3N4, Bi2S3, and g-C3N4/Bi2S3 composite catalysts were prepared via a facile one-pot microwave-assisted method and characterized. The orthorhombic phase and nearly spherical shape of the particles with an average diameter of 5-25 nm of g-C3N4/Bi2S3 composite were obtained from XRD and TEM. The composite also exhibits a high surface area (32.15 m(2)/g), which may provide convenient transportation and diffusion for substrate molecule. The optical studies were displayed the g-C3N4/Bi2S3 composite has a sharp absorption band in the visible region, higher charge separation, and reduced recombination rate. These results show that the Bi2S3 NPs have good crystallinity and are uniformly deposited on the surface of the g-C3N4 sheet. The catalytic performance of the g-C3N4/Bi2S3 composite for the reduction of 4-NP to 4-AP was exhibited approximately 100%, which is 1.48 and 2.34 times higher than the Bi2S3 and g-C3N4 catalysts, respectively. The pseudo-first-order rate constant was estimated as 1.648 x 10 (-2) min(-1) for the reduction of 4-NP using g-C3N4/Bi2S3 composite in 1 h reaction time. The effect of catalyst dosage (0-30 mg) was also investigated for the reduction of 4-NP using g-C3N4/Bi2S3 composite catalyst. Moreover, the reusability of the g-C3N4/Bi2S3 composite was exhibited a better reduction of the 4-NP even after 5 cycles and it was found that 8% reduction in the initial reduction rate. The obtained results from this study show that g-C3N4/Bi2S3 composite has the potential efficiency and stability to make it an ideal catalyst for the reduction of toxic effluents and wastewater treatment. [GRAPHICS] .