Controlling the charge carriers recombination kinetics on the g-C3N4-BiSI n-n heterojunction with efficient photocatalytic activity in N2 fixation and degradation of MB and phenol

Abstract

The challenges like the photocatalytic reduction of N2 and elimination of contaminants from the wastewater are accessible by low cost, stable, and visible-light-driven semiconductor-based photocatalysis. A novel g-C3N4/BiSI nanocomposite was synthesized by hydrothermal method and applied for the first time in photocatalytic nitrogen fixation and degradation of methylene blue dye and phenol. The physicochemical features of the photocatalysts were studied by XRD, XPS, FTIR, BET, DRS, FESEM, TEM, EDX mapping, PL, EIS, Mott-Schottky, and photocurrent techniques. Experimental results showed that the production of ammonia in the presence of g-C3N4/BiSI nanocomposite was 1280 μmolL−1g−1, while this values for g-C3N4 and BiSI were 274 μmol g−1 L−1 and 126 μmol g−1 L−1, respectively. Moreover prepared nanocomposite exhibited a higher rate constant in the MB (537.5 × 10−4 min−1) and phenol (353 × 10−4 min−1) degradation compared with the counterparts. The charge separation efficiency obviously improved, which was ascribed to the charges migration between g-C3N4 and BiSI in an n-n heterojunction system. In addition, high specific surface area and strong visible light absorption were identified as other factors affecting photocatalytic performance. This unique heterojunction photocatalyst has wide application prospects in environmental treatment.