Prof. Jinlong Yang’s group of Hefei National Laboratory for Physical Sciences and College of Chemistry and Material Science at USTC recently reported a new photosynthesis method for producing hydrogen from dissociated water molecules using incident near-infrared light. This finding was published on Phys. Rev. Lett.
As an ultimate solution for today’s more and more serious energy and environmental problems, solar energy is abundant and clean, and it can be converted into chemical fuel, biomass, or electricity, or directly stored as thermal energy. An important branch of solar-to-chemical energy conversion, hydrogen production from photocatalytic water splitting, viewed as an artificial photosynthesis, has been eagerly pursued since its first proposal in 1972. The key issue in photocatalytic water splitting is to develop photocatalysts with high solar energy conversion efficiency. However, until now, the infrared part of the solar spectrum, which constitutes almost half of the solar energy, has not been used, resulting in significant loss in the efficiency of solar energy utilization. Here, they propose a new mechanism for water splitting in which near-infrared light can be used to produce hydrogen. This ability is a result of the unique electronic structure of the photocatalyst, in which the valence band and conduction band are distributed on two opposite surfaces with a large electrostatic potential difference produced by the intrinsic dipole of the photocatalyst. This surface potential difference, acting as an auxiliary booster for photoexcited electrons, can effectively reduce the photocatalyst’s band gap required for water splitting in the infrared region. The new model is then verified in surface-functionalized hexagonal boron-nitride bilayers by first-principles electronic and optical calculations. Application of the new model to other photocatalytic processes is possible, presenting a promising future for near-infrared-light-driven photocatalysis. (Phys. Rev. Lett., 2014, 112, 018301)
http://prl.aps.org/pdf/PRL/v112/i1/e018301
