Influence of g-C3N4 and g-C3N4 nanosheets supported CuS coupled system with effect of pH on the catalytic activity of 4-NP reduction using NaBH4

The fabrication of g-C3N4 based narrow bandgap semiconductor catalysts with uniform dispersion and a strongly coupling interface is one of the main strategies to improve the catalytic activity of semiconductor materials. Here, the g-C3N4 coupled CuS (g-C3N4/CuS) composite catalysts were successfully fabricated via a simple sonochemical method using g-C3N4 nanosheets. The morphology, structure and optical properties of synthesized samples were investigated by SEM-EDS, TEM, XRD, FTIR, UV-vis DRS, PL, XPS, zeta potential, and N-2 adsorption/desorption measurements. The synthesized materials such as g-C3N4, bare CuS, and g-C3N4/CuS composite system were used for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) assisted with NaBH4. The synthesized composite material (g-C3N4/CuS composite) showed excellent catalytic activity for the reduction of 4-NP, compared with g-C3N4 and bare CuS. In addition, a series of experiments were employed to study the catalytic activity of g-C3N4/CuS composites with the effect of pH using phosphate buffer solutions for adjusting the pH of the solutions. The reusability, stability of g-C3N4/CuS catalyst has been checked by five recycling experiments. On the basis of the corresponding energy band positions, the mechanism of catalytic activity enhancement was proposed. This study extends a new chance of g-C3N4-based narrow bandgap semiconductor catalysts to the growing demand for cleaning of wastewater into the drinking water.