MIT Researchers Engineer Viruses as Scaffolds for Photocatalytic Water Oxidation

TEM images of the virus-templated IrO2 nanowires. Scale = 100 nm (a) and 10 nm (b). Source: Nam et al., Supplementary materials. Click to enlarge.

A team of MIT researchers, led by Dr. Angela Belcher, has engineered a common bacteriophage virus (M13) to function as a scaffold to mediate the co-assembly of zinc porphyrins (photosensitizer) and iridium oxide hydrosol clusters (catalyst) for visible light-driven water oxidation. The viruses become wire-like devices that can very efficiently split the oxygen from water molecules using solar energy.

To prevent the virus-wires from clumping together and lose their effectiveness over time, the researchers encapsulated them in a microgel matrix, so they maintained their uniform arrangement and kept their stability and efficiency. The advance is described in a paper published on 11 April in the journal Nature Nanotechnology.

Splitting water into hydrogen and oxygen comprises two half reactions: water oxidation and water reduction. Water oxidation is the more technically challenging half-reaction in the water splitting process, Belcher says, so her team focused on this part. Plants and cyanobacteria have evolved highly organized photosynthetic systems for the efficient oxidation of water, she noted. Other researchers have tried to use the photosynthetic parts of plants directly for harnessing sunlight, but these materials can have structural stability issues.

Belcher decided that instead of borrowing plants’ components, she would borrow their methods