Synthesis and optical properties of TDQD and effective CO2 reduction using a TDQD-photosensitized TiO2 film

• An organic dye, TDQD is synthesized.
• The photocurrent density increased in the TDQD-photosensitized-TiO2 film.
• The photocatalytic performance of the TDQD-photosensitized-TiO2 is superior to that of TiO2.
• The photoreduction of CO2 to CH4 is remarkably improved over TDQD-photosensitized-TiO2.

In an attempt to find a suitable visible light absorber, a TDQD[(E)-3-(5-(4-(5-(4-(bis(4-(hexyloxy)phenyl)amino)phenyl)thiophen-2-yl)-6,7-diethyl-[1,2,5]thiadiazolo[3,4-g]quinoxalin-9-yl)thiophen-2-yl)-2-cyanoacrylic acid] dye is synthesized and introduced onto the surfaces of commercialized TiO2 (P-25) particles as a photosensitizer to improve their photo-absorption in the visible range. The photocatalytic performance of the TDQD-photosensitized-TiO2 is superior to that of the non-photosensitized TiO2 nanomaterial: the photoreduction of CO2 to CH4 is remarkably improved on the former with the production of 1290 μmol gcat−1 L−1 of CH4 after 8 h of reaction. These results are attributed to the effective visible light absorption and charge separation, and the inhibited recombination of the photogenerated electron–hole pairs on the TDQD-photosensitized-TiO2. Finally, the prepared TDQD and TDQD-photosensitized-TiO2 powders were characterized through cyclic voltammetry (CV), ultraviolet-visible (UV–vis) and FT-IR spectroscopies and photocurrent density analysis.

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