The Zhao Research Lab
Our research involves areas of inorganic, organometallic, bioinorganic chemistry and chemical biology, with particular interest in the design and engineering of models for the oxygen-evolving center in photosystem II, through either synthetic methods using organic ligands or biosynthetic approach using small, stable and well-characterized proteins. These synthetic systems will be subjected to a variety of spectroscopic, structural characterization, reaction mechanism and activity studies to evaluate the properties and applications of these synthetic molecules.
Current Research Projects
The cofactors in PSII involved in light harvesting, electron transfer and water oxidation catalysis
( McEvoy, J. P.; Brudvig, G. W. Chem. Rev. 2006, 106, 4455)
The design of artificial catalysts for water oxidation represents a critical step in the conversion and storage of solar energy.
In order to understand the oxygen evolution reaction catalyzed by the OEC in PSII, our research focuses on the design of synthetic catalysts capable of water oxidation. The success of our research will offer experimental evidence for the proposed mechanisms of oxygen evolution in PSII, help to design next-generation catalysts for water oxidation and facilitate the development of alternative sources of energy, such as hydrogen, from water oxidation.
In natural photosynthesis, the conversion of light energy to chemical potential starts
from a charge separation process occurring at the P680 Chl a in the reaction center, producing the strongest known biological oxidant, an oxidized
charged radical P680+∙, which can oxidize the OEC via a redox-active tyrosine residue D1-Tyr161 to achieve
sunlight-induced water oxidation.
The major goal of artificial photosynthesis is to convert sunlight into high-energy chemicals, such as H2, from water oxidation. The successful capture, conversion and storage of solar energy require the design of artificial systems that can efficiently absorb sunlight, and create a charge separation to drive the oxidation of water. Although the creation of light-induced charge-separated state and electron transfer from various electron donors to electron acceptors have been reported, the coupling of efficient water oxidation catalysts to photoactive chromophores to realize light-induced water oxidation remains to be one of the greatest challenges in artificial photosynthesis. Our research aims to design photocatalysts to achieve light-induced water splitting, through the attachment of light-harvesting groups, such as ruthenium bipyridine complexes, to water oxidation catalysts in the presence of electron acceptors.
Through site-directed mutagenesis or covalent attachment, water oxidation catalysts, light-harvesting groups and electron acceptors could be incorporated into a protein scaffold to investigate how the spatial arrangement of these components will affect the energy and electron transfer process, thus providing guidelines for the design of better photocatalysts for water oxidation.