Photocatalytic properties of TiO2 and Fe-doped TiO2 prepared by metal organic framework-mediated synthesis

Abstract

The Ti-containing metal organic framework (MOF) MIL-125 has been used as sacrificial precursor to obtain TiO2 materials through the MOF-mediated synthesis route. In this study, Fe 3+ was deposited on the surface of MIL-125 after its hydrothermal synthesis. Targeted Fe-doped titania photocatalysts were prepared through the direct calcination in air of Fe/MIL-125 crystals and/or by using a two-step method, including carbonization in inert atmosphere followed by calcination in air. The relationship between the synthesis conditions and the properties of the Fe-doped titania nanopowders, such as Fe content, porosity, phase composition and particle size was investigated.From elemental mapping, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, UV-Vis absorption spectroscopy and photoluminescence emission spectra, the presence of highly dispersed Fe 3+ ions incorporated into the TiO2 crystal lattice was confirmed, which led to a significant red shift of photoresponse towards visible light and reduced the recombination rate of electron-hole pairs at low iron content. By varying the pre-carbonization temperature, both crystal size and phase composition in the final materials were modulated. The performance of Fe-doped titania materials in photocatalytic water-splitting was tested for hydrogen evolution. Optimal photocatalytic performance was found at 0.15 and 0.5 wt. % iron concentration and exceeded those of non-doped titania and commercial anatase both under visible and UV light irradiation, respectively, and among the highest reported in literature for these systems.

Metal‐Organic Framework MIL‐125 Derived Mg2+‐Doped Mesoporous TiO2 for Photocatalytic CO2 Reduction

“…The average pore size of the samples falls in the mesoporous range, which is consistent with the H2 hysteresis loops observed in N 2 adsorption-desorption isotherm. There seems to be a trend where the photocatalysts surface area increases with the concentration of Mg 2 + , a similar trend was also found on Fe 3 + treated MIL-125 derived TiO 2 materials, [37] which suggests successful doping of Mg 2 + into the mesoporous TiO 2 lattice. This trend is also found in pore volume and pore size distribution.…”

“…This cation adsorption process produces additional favorable properties and broadens the functionalities and applications of MOF derived metal oxide materials. For example, Valero‐Romero et al [37] . reported Fe‐doped porous TiO 2 photocatalysts prepared by applying Fe 3+ adsorption process on MIL‐125 followed by thermal treatments.…”

“…[36] This cation adsorption process produces additional favorable properties and broadens the functionalities and applications of MOF derived metal oxide materials. For example, Valero-Romero et al [37] reported Fedoped porous TiO 2 photocatalysts prepared by applying Fe 3 + adsorption process on MIL-125 followed by thermal treatments. The Fe-doped porous TiO 2 significantly enhanced photocatalytic water splitting performance and lowered the electron-hole recombination rate compared with pristine TiO 2 .…”

“…Based on the aforementioned literature review, it was hypothesized that the Mg 2 + adsorption process on MIL-125 and followed by thermal treatments can lead to Mg 2 + doped TiO 2 materials with mesoporous structures. The doped Mg 2 + into TiO 2 lattice does not merely function as doped Fe 3 + , [37] which mainly facilitates charge separations; more importantly, the Mg 2 + doping on TiO 2 is further beneficial for enhancing CO 2 affinity due to the alkaline nature of Mg. The merits of Mg 2 + doping should considerably enhance photocatalytic performance for CO 2 reduction process.…”

Heterostructured g-CN/TiO2 Photocatalysts Prepared by Thermolysis of g-CN/MIL-125(Ti) Composites for Efficient Pollutant Degradation and Hydrogen Production

“…1700 m 2 g −1 ) [39]. MIL-125(Ti) is a good precursor of TiO 2 nanocrystals [40,41] that demonstrated a good photocatalytic activity for CO 2 reduction, As(III) oxidation or pollutant degradation [42][43][44][45][46][47][48].…”