Alkali modified P25 with enhanced CO 2 adsorption for CO 2 photoreduction.

To improve the CO 2 adsorption on the photocatalyst, which is an essential step for CO 2 photoreduction, solid solutions were fabricated using a facile calcination treatment at 900 °C. Using various alkalis, namely NaOH, Na 2 CO 3 , KOH, K 2 CO 3 , the resulted samples presented a much higher CO 2 adsorption capacity, which was measured with the pulse injection of CO 2 on the temperature programmed desorption workstation, compared to the pristine Evonik P25. As a result, all of the fabricated solid solutions produced higer yield of CO under UV light irradiation due to the increased basicity of the solid solutions even though they possessed only the rutile polymorph of TiO 2 . The highest CO 2 adsorption capacity under UV irradiation was observed in the sample treated with NaOH, which contained the highest amount of isolated hydroxyls, as shown in the FTIR studies.