[El Gato]

The only real breakthrough here is a more efficient electrolysis of water

Not if it used the sunlight directly rather than having to turn it into electricity first. That's got to be way more efficient. It's also what the now decayed plants that comprise crude oil did.

[FreedomOfExpression]

Not if it used the sunlight directly rather than having to turn it into electricity first. That's got to be way more efficient.

From the article:
When electricity - whether from a solar photovoltaic cell, a wind turbine or any other source - runs through the electrode, the cobalt and phosphate form a thin film on the electrode, and oxygen gas is produced.

The solar energy has to be converted into electricity first, it appears.