Understanding the synergistic adsorption-photocatalytic degradation of EE2 using ZnO/Bi2MoO6{0 1 0}

Abstract

Endocrine disrupting chemicals (EDCs) have adverse effects on the aquatic environment and human health as well. In this study, a ZnO/Bi2MoO6 {0 1 0} composite photocatalyst was fabricated via a simple hydrothermal calcination method for the efficient and synergistic adsorption-photocatalytic degradation of an environmental endocrine disruptor, 17α-ethynylestradiol (EE2). Adjusting the pH of the synthetic procedure, selectively exposed the highly reactive {0 1 0} crystalline surface of Bi2MoO6, and the surface hydrophilicity of the material decreased, enhancing the adsorption efficiency (74.74%) of the hydrophobic EE2 molecule. Density functional theory calculations showed that the chemisorption of the EE2 molecules takes place on the Bi2MoO6{0 1 0} surface owing to the binding of hydroxyl groups. Furthermore, by incorporating energy-band-matched ZnO to form heterojunctions with Bi2MoO6{0 1 0}, the obtained composites achieved a removal rate of 90% for EE2 after 40 min of visible light catalysis. Capture experiments and electron paramagnetic resonance spectra revealed that h+ and •O2- were the main active species, and the catalytic mechanism followed was that of a type II reaction. This study introduced a new strategy for the modification of photocatalysts resulting in a stable change in their surface properties for enhanced pollutant removal efficiency.