Preparation, suppressed the charge carriers recombination, and improved photocatalytic performance of g-C3N4/MoS2 p-n heterojunction photocatalyst for tetracycline and dyes degradation upon visible light

Abstract

Operative charge separation, visible spectrum absorption, and increase of active sites are considered as effective factors in improving the performance of photocatalysts in the design of photocatalytic systems. Among photocatalysts, graphite carbon nitride (g-C3N4) has been used in various fields, but research is still ongoing to achieve superior photocatalysts based on g-C3N4. In this work, the vision was to enhance the photocatalytic accomplishment of g-C3N4 through the construction of p-n heterojunction with MoS2 semiconductor. The physicochemical properties of the as-synthesized photocatalysts were evaluated by TEM, FESEM, HRTEM, EDX, mapping, FT-IR, XRD, BET, XPS, PL, UV–vis DRS, photocurrent, EIS, and Mott-Schottky. The prepared photocatalysts were employed under visible light to degradation of tetracycline (TC), and the g-C3N4/MoS2 nanocomposite achieved a rate constant of 547 × 10−4 min−1, which was 12.7 and 17.4-folds higher than g-C3N4 and MoS2, respectively. Degradation of rhodamine B (RhB) and methylene blue (MB) as dye contaminants also showed that the photocatalytic activity of the nanocomposite was improved relative to the constituents. The planar structure of g-C3N4 and MoS2 gives a shorter path for the transfer of charge carriers to the surface, thus increasing the efficiency of the photocatalyst. Also, the different analysis and experimental tests showed that the improvement of visible spectrum absorption, high specific surface area, and p-n heterojunction construction led to increased production of active species and suppressed recombination of electron-hole pairs, thereby significantly ameliorating photocatalytic activity. The charge migration mechanism between g-C3N4 and MoS2 was carefully investigated and discussed. The present work could offer new acumen into the synthesis and application of g-C3N4 -based heterojunctions.