Room-temperature preparation of MIL-68 and its derivative In2S3 for enhanced photocatalytic Cr(VI) reduction and organic pollutant degradation under visible light

MIL-68, a typical In-based MOF, has been studied in many fields due to its excellent performance. Facile preparation of MIL-68, suitable for scalable preparation and industrial applications, is of great significance. In this work, a method for the room-temperature preparation of rod-like MIL-68 at the nano- and micro-scales was developed for the first time, in which water or salts such as NaF, sodium formate, sodium acetate and sodium propionate were used as modulating reagents. It appears that these modulating reagents can promote the deprotonation of terephthalic acid and the hydrolysis of indium salt to accelerate crystal nucleation. The size of MIL-68 can be controlled by changing the modulating reagents. Hollow porous In2S3 particles composed of assembled ultrathin nanosheets were obtained via sulfidation treatment using MIL-68 as a self-sacrifice template, and the obtained In2S3 exhibited excellent photocatalytic activity toward Cr(VI) reduction and methyl orange degradation under LED visible light irradiation. Furthermore, the photocatalytic mechanism and reusability were studied.