Increased photocatalytic activity of CuO/TiO2 through broadband solar absorption heating under natural sunlight

摘要

Photocatalytic activity harnessing natural sunlight is highly desirable in terms of renewable energy. However, the broad spectrum of the sun means that only certain parts of the spectrum can be absorbed by the photocatalysts. Conventional approaches include designing photocatalyst materials with narrower band gaps to utilize the higher wavelengths. However, such materials often face stability issues, and degrade quickly over time. A shift of paradigm would be to use the existing stable photocatalysts and using the other portion of the solar spectrum to boost its performance. The spectrum not absorbed in the photocatalytic reaction can be absorbed and converted into thermal energy, which is shown to increase the rate of photocatalytic reaction. Herein, we have designed a photocatalyst coupled with a co-catalyst that allows for broadband absorption of the solar spectrum, and utilize parts of this spectrum to convert into heat. This synergistic approach allows for the capturing of sunlight for both photocatalysis and thermal heat generation, without much modification to the original photocatalyst. The increase in temperature lead to an increase of photocatalytic H2 production by 40-fold for pure TiO2, and outdoor testing has also verified the feasibility of using natural sunlight as a source of light and heat energy for photocatalysis.