Photocatalytic Splitting of Water into Hydrogen and Oxygen

Abstract

One of the best solutions for meeting future energy demands is the conversion of water into hydrogen fuel using solar energy. The splitting of water into molecular hydrogen (H₂) and oxygen (O₂) using light involves two half-reactions: the oxidation of water to O₂ and the reduction of protons to H₂. To take advantage of the full range of the solar spectrum, researchers have extensively investigated artificial photosynthesis systems consisting of two photosensitizers and two catalysts with a Z-configuration: one photosensitizer-catalyst pair for H₂ evolution and the other for O₂ evolution. In this lecture, the speaker will review advances his laboratory has made in the development of new systems for photocatalytic H₂ evolution that uses earth-abundant materials and is both efficient and durable. He and his research group constructed several assemblies of CdTe and CdSe QDs as photosensitizers with [FeFe]-H₂ase mimics as catalysts. These assemblies produced H₂ in aqueous solutions photocatalytically and efficiently, with turnover numbers (TONs) up to tens of thousands. Assemblies of 3-mercaptopropionic acid (MPA)-capped CdTe QDs with Co²⁺ ions formed Co_h-CdTe hollow nanospheres, and (MPA)-capped-CdSe QDs with Ni⁺ ions produced Ni_h-CdSe/CdS core/shell hybrid in situ in aqueous solutions upon irradiation. The resulting photocatalytic systems proved robust for H₂ evolution. These systems showed excellent activity and impressive durability in the photocatalytic reaction, suggesting that they can serve as a valuable part of an overall water splitting system. Recently he also constructed photocatalytic systems for oxidation of water.

About the speaker

Prof. Tung Chen-Ho obtained his BSc from the University of Science and Technology of China in 1963 and joined the Institute of Photographic Chemistry, Chinese Academy of Sciences (CAS) as a Research Associate in 1974. He then went to US and received his PhD in Organic Chemistry from Columbia University in 1983 and returned to China. He is currently the Professor and Academician in CAS.

Prof. Tung’s research focuses on organic photochemistry, particularly on microenvironment effects on photochemical reactions, hydrophobic-lipophilic effects on photochemical and photophysical processes, and photoinduced electron transfer and energy transfer. By using microporous solids as the reactors, he successfully synthesized large-ring compounds in high yields even at high substrate concentrations.

Prof. Tung has published over 150 papers, and received numerous awards including the Second Prize of the CAS Natural Science Award (1992), Ho Leung Ho Lee Foundation for Scientific and Technological Progress Award (2003), Second Prize of the Chinese National Natural Science Award (2005) and the Asian and Oceanian Photochemistry Association Award (2008).