Making hydrogen from water and solar light is certainly better than using nuclear energy for that.

There is no reason for consuming valuable nuclear fuel, for which better uses exist, instead of using free solar light.

The efficiency of converting solar energy into hydrogen is already acceptable. The same is true for the efficiency of converting hydrogen and concentrated carbon dioxide into synthetic hydrocarbons, which are the best means for long term energy storage, and also for applications like aircraft and spacecraft.

The least efficient step remains concentrating the diluted carbon dioxide from air.

While the efficiency of converting solar energy and water into hydrogen by artificial means is already better than that of living beings, the living beings are still much more efficient in converting H2 and CO2 from air into organic substances.

Besides improving the efficiency of the existing techniques, an alternative method of CO2 capture would be the genetic engineering of a bacterium that would produce some usable oil from H2 and air, with an improved productivity over the existing bacteria, which use most of the captured energy to make substances useful for them, not for us, so unmodified bacteria would not have a high enough useful output.

> Making hydrogen from water and solar light is certainly better than using nuclear energy for that.

Using heat is the most efficient and if you use nuclear heat directly, and you don't have to go to the step of converting to electricity, you get huge efficiency.

> There is no reason for consuming valuable nuclear fuel

Nuclear fuel is not valuable once you have a closed cycle. Fuel cost are already only a few % of total nuclear cost and in a closed cycle would be almost nothing. As soon as you breed fuel from fertile material the cost is basically 0.

> The efficiency of converting solar energy into hydrogen is already acceptable.

It requires a very large plant to do in many small batches and cost 20x what hydrogen costs from natural gas. Its not efficient and will not be for the next 20+ years at least.