Scientists boost solar hydrogen output by capturing long sun waves

Researchers at the Institute of Science Tokyo have developed a novel photocatalyst that significantly enhances solar hydrogen production by capturing longer wavelengths of sunlight. By substituting ruthenium with osmium in the dye-sensitized photocatalyst, the team extended light absorption from the conventional limit of 600 nanometers up to 800 nanometers. This broader absorption range allows the system to harness a larger portion of the solar spectrum, resulting in up to twice the solar-to-hydrogen conversion efficiency compared to traditional ruthenium-based dyes. The key to this improvement lies in the heavy-atom effect of osmium, which facilitates singlet–triplet electronic transitions that enable absorption of lower-energy, longer-wavelength light. This advancement addresses a major limitation of existing solar hydrogen systems, which typically absorb only shorter visible wavelengths and thus waste much of the available solar energy, especially under low-light or cloudy conditions. The new osmium-based photocatalyst maintains system simplicity while improving performance, making it more practical for