Facile and Controllable Modification of 3D In2O3 Microflowers with In2S3 Nanoflakes for Efficient Photocatalytic Degradation of Gaseous ortho-Dichlorobenzene

Novel 3D In2S3/In2O3 heterostructures comprised of 3D In2O3 microflowers and In2S3 nanoflakes were synthesized via a facile hydrothermal process followed by an in situ anion exchange reaction. In the In2S3/In2O3 heterostructures, the In2S3 nanoflakes were in situ generated and uniformly assembled on In2O3 microflowers. The microstructures, optical properties, oxygen vacancy concentration, and photoreactivity of the heterostructures could be tuned by adjusting the amount of sulfide source. The effect of In2S3-nanoflakes modification on the oxygen vacancy concentration, optical properties, charge carrier separation, and charge carrier lifetime of In2O3 were investigated systematically. The catalytic activity of the proposed heterostructures for degradation of gaseous ortho-dichlorobenzene (o-DCB, a representative chlorinated volatile organic compounds) was higher than that of either unmodified In2O3 or TiO2 (P25). Meanwhile, oxygen vacancies, systematically explored by Raman, X-ray photoelectron spectroscopy (XPS), and low-temperature electron spin resonance (ESR) spectroscopy, were demonstrated to have a two-side effect on the photocatalytic performance. Particularly, the main reaction products including o-benzoquinone type species, phenolate species, formates, acetates, and maleates were verified with in situ FTIR spectroscopy. Additionally, ESR examination confirmed that •OH and •O2– were the predominant reactive oxygen species involved in the degradation of gaseous o-DCB. The current research provides new insight into utilizing In-based heterostructures as promising and efficient visible-spectrum-responsive catalysts for the removal of harmful chlorinated volatile organic compounds.