Photothermal CO2 hydrogenation to methanol over a CoO/Co/TiO2 catalyst in aqueous media under atmospheric pressure.

• A CoO/Co/TiO 2 was prepared and used in photothermal CO 2 hydrogenation to CH 3 OH. • The CoO semiconductor film was formed with a thickness of 5–6 nm from air oxidation. • Co0 species are stable at the interface of Co NPs with TiO 2. • A Z scheme mechanism was proposed for CH 3 OH formation with 39.6 μmol g cat –1 h–1. Catalytic conversion of CO 2 into methanol is of particular interest as it does not only provide valuable methanol, but also utilize the waste CO 2. In the present work, a CoO/Co/TiO 2 catalyst was developed and utilized in catalyzing CO 2 to methanol under photothermal conditions. From the results of characterization, the supported Co nanoparticles (NPs) were composed of Co0 in the bulk, CoO film formed from air oxidation on the surface, and Co0 at Co NPs-TiO 2 interfaces. This structure provided the possibility for a Z scheme photothermal catalytic system, which revealed a high activity for methanol formation in aqueous media under atmosphere pressure. It was proposed that the light excited electrons from the valence band (VB) of TiO 2 , and the excited electrons could enhance the Co0 catalytic activity under thermal conditions. The present approach will offer a new strategy to design Co based Z scheme catalysts and further improve the conversion efficiency from CO 2 to fuels. [ABSTRACT FROM AUTHOR]