Photothermal Catalytic Water Splitting at Diverse Two-Phase Interfaces Based on Cu-TiO2

Wasted high-temperature water from power plants or industrial boilers for photothermal catalytic water splitting reactions may be used to produce solar fuel and provide high-temperature heat to achieve solar-energy cascade utilization. Cu-modified TiO2 was used for the overall photothermal catalytic water splitting reaction, resulting in a hydrogen-oxygen ratio of approximately 2:1. The liquid-solid interface reaction yield was up to 10 times that of the gas-solid interface at the same reaction temperature. With the Cu modification, the photoresponse was improved, the energy barrier of the rate-determining step was reduced, and the water splitting reaction was promoted. As the copper content increased, Cu elements changed from a low valence state to an oxidized state. Moreover, the effect of temperature on the reaction was also explored. Increasing the temperature reduced the energy barrier of the rate-determining step and reduced the charge-transfer resistance, which explains the positive correlation between the hydrogen yield and temperature.