In-situ infrared investigation of m-TiO2/α-Fe2O3 photocatalysts and tracing of intermediates in photocatalytic hydrogenation of CO2 to methanol

Abstract

There is an urgent need for technologies to combat acute global climate change. To tackle this challenging task, the research group aims to develop a novel catalyst to serve CO2, a kind of infamous greenhouse gas, as a sustainable carbon resource contributing to the green productions of fine chemicals. Here in this work, the heterojunction photocatalyst containing mesoporous TiO2 (m-TiO2) and α-Fe2O3 has been deployed for the conversion of CO2 and H2O into CH3OH at 300 °C. The photocatalysts are synthesized by the sol-gel method and characterized by various techniques to study their physical and chemical properties. The dark adsorption experiments for these as-prepared photocatalysts were carried out in the airtight gas cell from vacuum to different pressure gradients with CO2 at ambient temperature by the transmission mode of FTIR measurements. Moreover, the associated intermediate species of CO2 hydrogenation were identified by diffusive reflectance infrared techniques (DRIFT). By using CO2 temperature programmed desorption (TPD) analysis, the higher CO2 adsorption capacity of m-TiO2/α-Fe2O3 heterojunction (0.054 mmol/g) was confirmed than that of the α-Fe2O3 (0.017 mmol/g) and m-TiO2 (0.015 mmol/g).