TiO₂ nanocrystals with the {001} and {101} facets co-exposed with MIL-100(Fe): an egg-like composite nanomaterial for efficient visible light-driven photocatalysis

The exposure of a specific crystal face to a specific composition or a suitable carrier composition with synergistic effects can effectively improve the photocatalytic activity of the material and enhance its practical value. For choosing an ideal carrier, the primary factor is a large specific surface area. Herein, by using MIL-100(Fe) as the carrier, an egg-like TiO₂/MIL-100(Fe) composite was successfully prepared, for the first time, via a facile two-pot hydrothermal method. XRD, SEM, TEM and other characterization methods showed that when the molar ratio of Ti : Fe was 0.3 : 1, the morphology of the TiO₂/MIL-100(Fe) composite was completely egg-like. The TEM results showed that the {001} and {101} facets of TiO₂ in the TiO₂/MIL-100(Fe) composite were co-exposed. The BET results showed that the TiO₂/MIL-100(Fe) composite had a large specific surface area and pore size. The larger pore size provided an effective channel for the photocatalytic degradation of MB and the interfacial effect of TiO₂ and MIL-100(Fe). The separation efficiency of the photogenerated electron-hole pairs was effectively improved. The efficiency of 30% TiO₂/MIL-100(Fe) in the photocatalytic degradation of MB reached 99.02% in 30 min under visible light. All these findings showed that the composite of the effectively charge-separated photocatalytic semiconductor and the porous MOF with a high specific surface area had a high potential application value for the photocatalytic degradation of organic pollutants.