Engineered CO2 conversion performance of nanostructured TiO2 photocatalysts via electrochemical hydrogenation

Modification of TiO2 by the hydrogenation process is one of the promising ways to achieve favorable properties for efficient photocatalytic CO2 conversion but typical chemical hydrogenation methods such as H2 thermal treatment and the use of hydrides are not easy to control for practical application. Moreover, the study on the applications to photocatalytic CO2 conversion by using electrochemically hydrogenated TiO2 nanotubes (TNTs) has not been fully implemented. In this work, we demonstrate the fabrication of hydrogenated TiO2 nanotubes (TNTs) via an electrochemical method for photocatalytic CO2 conversion. The hydrogenated TNT surface is well-controlled in a few nm regime, with varied reaction voltages. The hydrogenated TNT photocatalysts display a remarkable production rate of 0.57 μmol cm−2 h−1 (= ca. 297 μmol g−1 h−1) of CH4, which is four times higher than that by bare TNT. These significantly enhanced photocatalytic performances are attributed to the synergistic effects of hydrogenated nanostructures of the TiO2 surface, which represent enhanced light absorption, highly ordered nanostructures, and improved electrical properties due to the electrochemical hydrogenation.