Harnessing infrared solar energy with plasmonic energy upconversion

Solar radiation is the most abundant renewable energy source, however, its overall utilization remains inefficient as half of the energy is in the form of infrared (IR) light, which cannot be harnessed due to its low energy. Upconversion (UC) is an effective means of converting IR radiation to high-energy light. Here, we show a plasmonic CuS/CdS heterostructured semiconductor that can generate energy comparable to that of visible light from IR radiation, with a high efficiency of up to 5.1%. The unique charge dynamics of this system lead to efficient carrier transfer and long-lived charge separation. As a result, photocatalytic coupled redox reactions occur, including oxidation of methanol to formaldehyde and hydrogen evolution, with activities maintained over one week. This work demonstrates the promise of plasmonic UC for utilizing sustainable energy from low-flux IR light.