Enhanced photothermal catalysis for CO₂ reduction with H₂O by amphoteric metal oxides modified TiO₂

Due to competitive adsorption between CO₂ and H₂O, hydrogen evolution reaction reacts easily in the photothermal CO₂ reduction. Herein, the amphoteric oxide loaded on TiO₂ catalyst was prepared to enhance CO₂ adsorption as well as improve the photo-responsive properties. The samples with 10% mass fraction of ZnO loaded on TiO₂ exhibited the best photothermal catalytic performance. The average yields of H₂, CO and CH₄ were estimated to be 35.7, 43.5, and 5.7 μmol/(g·h), respectively. Also, the selectivity of carbon-containing products increased from 28.9% to 48.8% when compared to P25. The loading of amphoteric oxides can act as adsorption sites on the material surface to adsorb acidic molecules of CO₂ for reaction, improving the selectivity of carbon-containing products. In addition, amphoteric oxides are good semiconductors, which can improve the photo-responsive properties of the catalyst and form heterostructures with TiO₂ to promote the separation of photogenerated electron–hole pairs, allowing more photo-generated carriers to participate in the reaction. Finally, both functions including CO₂ adsorption and solar light absorption could be realized on the all-in-one amphoteric oxide loaded on TiO₂ component.