A mechanistic study on enhanced solar photocatalytic activity of SnWO4/BiMoO6 nanocomposites for degradation of tetracycline

Abstract

Step-scheme band configuration is considered to be an excellent option for photocatalytic applications including degradation of organic pollutants. This phenomenon has been demonstrated here via sunlight mediated photocatalytic degradation of trace concentrations of antibiotics in water by SnWO4/BiMoO6 nanocomposites. The structural, morphological, textural, compositional and optical properties of the hydrothermally synthesized SnWO4/BiMoO6 nanocomposites are critical towards enhanced photocatalytic degradation kinetics of tetracycline, used here for mimicking antibiotic residue in water. The optimized batch of 0.10SnWO4/Bi2MoO6 photocatalyst exhibited step-type band position and accounted for 95 % sunlight mediated photocatalytic degradation of tetracycline solution at a rate constant of 0.031 min−1. The degradation rate is six times higher than that of pristine Bi2MoO6 and fifteen times higher than that of SnWO4 nanoparticles. The mechanism involved in the photocatalytic degradation of tetracycline hydrocloride has been addressed in the light of (a) enhanced absorption of sunlight by 0.10SnWO4/Bi2MoO6; (b) favourable type-II-like band position of Bi2MoO6 and SnWO4 leading to heterojunction formation, (c) electrochemical studies showing charge carrier mobility and photocurrent measurements showing inhibition of charge carrier recombination, and (d) in situ generation of hydroxyl radicals.