Concentrated Full-Spectrum Solar-Driven CO2 Reduction with H2O to Solar Fuels by Au Nanoparticle-Decorated TiO2

Currently, the production of solar fuels by the photoreduction of CO2 with H2O is limited by the slow reaction rate and low efficiency of solar energy conversion. Combining concentrated solar power and plasmonic nanomaterials is a promising strategy to enhance photothermal transformation and promote solarto-fuel conversion. Herein, a nanocatalyst comprising gold anchored on TiO2 was fabricated using a regular deposition-precipitation method. The nanocatalyst showed improved performance in CO2 reduction with H2O under concentrated full-spectrum irradiation owing to the coupling of photo- and thermal energies. Macroscopic experiments demonstrated a clear correlation between the light intensity and the syngas yield, and a CO2 conversion rate of 6.35% was achieved after 3 h under simulated sunlight illumination of 1644 mW/cm(2). Photoelectrochemical measurements and finite element method simulations indicated that Au/TiO2 achieved better separation and transport of the photoexcited carriers than TiO2 owing to localized surface plasmon resonance that heats the nanocatalysts under concentrated full-spectrum irradiation. In situ diffuse reflectance infrared Fourier transform spectroscopy analysis also suggested that the photothermal effect accelerates the formation of intermediates such as formate and acetate and therefore enhances the overall photocatalytic rate. These results highlight the excellent potential of combining concentrated solar power and plasmonic nanostructures to realize the synergistic utilization of photon energy and thermal energy. Such a combination not only promotes the solar-to-fuel conversion efficiency but also paves the way for future applications in large-scale scenarios.