A highly efficient and stable TiO2@NH2-MIL-125 material for enhanced photocatalytic conversion of CO2 and CH4

Abstract

At present, there are many difficulties in accomplishing the effective and efficient chemical utilization of CO2, such as low catalyst stability, high energy consumption, limited conversion of CH4 by reforming due to thermal reaction kinetics, high reaction temperature and high demand on reactor material. Here, a novel composite catalyst TiO2/NH2-MIL-125, prepared by three different methods, was applied to the photocatalytic conversion of CO2 with CH4 under visible-light irradiation. The experimental results showed that NH2-MIL-125@TiO2-40 catalyst prepared by ultrasonic impregnation method achieved rapid conversion of CO2 and CH4 at room temperature, and the yield of CO was up to 159 μ mol/g, which was 510% great than the catalytic performance of TiO2. In addition, the photocatalytic reduction efficiency of NH2-MIL-125@TiO2-40 material held stay at 93.7% after continuous operation for 28 h, showing excellent photocatalytic stability. Moreover, a series of characterization techniques were used to study the structure, morphology and photoelectric chemical properties of the photocatalyst. As well, the relationship between the physical and chemical properties of the material and the catalytic performance of CO2 conversion is discussed. Based on the above studies, a possible catalytic mechanism for the photocatalytic conversion of CO2 by NH2-MIL-125@TiO2 hybrid materials is proposed.