A group of scientists are developing a type of “artificial leaf” that mimics a real leaf's chemical transformation through photosynthesis, by converting sunlight and water into liquid fuels such as methanol that can be used in cars and trucks.

The study on how to mimic photosynthesis using synthetic materials, such as the “artificial leaf”, was a central theme of a recent major symposium on the progress and challenges of solar energy. As part of a drive towards reducing the dependence on fossil fuels as a non-sustainable resource, solar power is seen as one of the most promising alternatives, although part of the problem is making any option affordable for large-scale use.

The researchers, including Kazunari Domen of the University of Tokyo, Etsuko Fujita of Brookhaven National Laboratory, New York and Koji Tanaka of the Institute of Molecular Science in Okazaki, Japan, described the development of catalysts for both hydrogen and oxygen production, and how to build an “artificial leaf” through coupling water splitting and CO2 reduction artificial photosynthesis.

The goal of artificial photosynthesis is to produce a liquid fuel, such as methanol, or “wood alcohol,” which would create an “artificial leaf” that not only splits water but uses the reaction products to create a more usable fuel, similar to what leaves do when they capture and convert sunlight into chemical fuel through photosynthesis, a process that involves the conversion of water and carbon dioxide into sugars as well as oxygen and hydrogen.

Researchers have already found ways of mimicking this artificial photosynthesis and fuel-making process, but are now looking at the challenges of making solar a viable alternative to fossil fuels on a commercial basis.

One of the presenters, Kazunari Domen, whose work has been published in a number of publications (including Wang et al., Nature Mater (2008) doi: 10.1038/NMAT2317), discussed his research on the development of more efficient and affordable catalysts for producing hydrogen using a new water-splitting technology, entitled “photocatalytic overall water splitting.” This technology uses light-activated nanoparticles to convert water into hydrogen.

The 1st Annual Chemical Sciences and Society Symposium, as reported in Chemical & Engineering News, consisted of 30 top chemists from China, Germany, Japan, the UK and the US, and was organized through a joint effort of the science and technology funding agencies and chemical societies of each country. As well as looking at ways of transforming solar energy into chemical fuel, it also explored ways of employing biomass to convert sunlight into usable energy, creating innovative photovoltaics, and storing solar energy in batteries and as fuel, was part of a new effort to initiate international cooperation and innovative thinking on the global energy challenge.