Facile preparation of dual Z-scheme Bi2O3/g-C3N4/Ag6Si2O7 photocatalyst for highly efficient visible-light photocatalytic degradation of organic pollutants

Abstract

To construct composite photocatalysts with satisfactory visible light response, excellent redox ability, high electron-hole separation efficiency and good stability, herein, a new Bi2O3/g-C3N4/Ag6Si2O7 ternary photocatalyst was prepared employing a simple method via in situ deposition of Ag6Si2O7 on Bi2O3/g-C3N4 composite surface. XRD, XPS, EDS, TEM, HRTEM, FESEM, UV–vis DRS, FTIR, ESR, PL and EIS determination were used characterized the ternary composite. The influences of mass ratios of (Bi2O3 + g-C3N4)/Ag6Si2O7 on photocatalytic performance under visible light were investigated. Bi2O3/g-C3N4/Ag6Si2O7 (1:25.5) was found to have highly efficient photocatalytic performance for different dyes and colorless organic contaminants. The photocatalytic apparent rate constant for methylene blue (MB) attained 61.57, 49.52, 1.87, 27.78, 1.44, 1.84 and 2.20 times that by sole Bi2O3, g-C3N4, Ag6Si2O7, binary composite Bi2O3/g-C3N4, g-C3N4/Ag6Si2O7, Bi2O3/Ag6Si2O7, and physical mixture of Bi2O3/g-C3N4 and Ag6Si2O7 with the same mass ratio of (Bi2O3 + g-C3N4)/Ag6Si2O7, respectively. The composite kept good activity after three recycling runs. The photocatalytic degradation of tetracycline (TC) and rhodamine B (RhB) was also obviously improved. The excellent photocatalytic performance and efficient separation process of photogenerated carriers could be well elucidated by dual Z-scheme mechanism. The development of dual Z-scheme Ag6Si2O7 based composite has great significance for efficient removal of organic contaminants.