Construction of Z-scheme g-C3N4 / MnO2 /GO ternary photocatalyst with enhanced photodegradation ability of tetracycline hydrochloride under visible light radiation

A facile wet-chemical method was adopted to synthesize g-C3N4/MnO2/GO heterojunction photocatalyst for visible-light photodegradation of tetracycline hydrochloride (TC). The addition of MnO2 and GO increased the absorption of visible light and the specific surface area of the photocatalyst. The results of photoluminescence, electrochemical impedance spectroscopy, and photocurrent response indicated that CMG-10 had the lowest electron–hole recombination probability, which was beneficial for the photocatalytic reaction. The ternary photocatalyst exhibited enhanced photoelectric performance and superior photocatalytic activity with 91.4% removal of TC (10 mg/L) under a mere 60 min visible light illumination, which showed enhanced photocatalytic degradation when compared with binary (CM, 77.95%; CG, 78.83%) and single (C3N4, 55.5%; MnO2, 36.41%) photocatalysts. A pH of 6 was optimal for the CMG-10 photocatalytic degradation of TC, and the optimal photocatalyst dosage was 0.5 g/L. Common coexisting ions influenced the removal of TC by influencing the production of active species. The catalyst is stable and reusable with only a 10% reduction in removal efficiency after four cycles. According to the active species analysis, the Z-scheme mechanism was a charge transfer behavior in the composite photocatalyst, which could prevent the recombination of photogenerated carriers. This study presents a photocatalytic approach to the effective removal of TC from water bodies, which provides practical implications to advance the use of photocatalytic technology in the restoration of aqueous environmental pollution.