The Holy Grail of artificial photosynthesis — which would enable people to imitate plants’ ability to turn sunlight directly into electrochemical energy — might today be a bit closer, according to researchers at the US Department of Energy’s Lawrence Berkeley National Laboratory.

Scientists there say that’s because they’ve recently discovered that nano-sized crystals of cobalt oxide can, like plants, perform the “critical photosynthetic reaction of splitting water molecules.”

“Photo-oxidation of water molecules into oxygen, electrons and protons (hydrogen ions) is one of the two essential half-reactions of an artifical photosynthesis system — it provides the electrons needed to reduce carbon dioxide to a fuel,” said chemist Heinz Frei. “Effective photo-oxidation requires a catalyst that is both efficient in its use of  solar photons and fast enough to keep up with solar flux in order to avoid wasting those photons. Clusters of cobalt oxide nanocrystals are sufficiently efficient and fast, and are also robust (last a long time) and abundant. They perfectly fit the bill.”

He added, “This is the next important challenge in the field of artificial photosynthesis for fuel production.”

Scientists say artificial photosynthesis could help us produce liquid fuel for transportation that is both renewable and carbon-neutral.

• Science inches closer to artificial photosynthesis, solar fuels